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  • 51.
    Karlsson, Markus
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Forsgren, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Dahlström, Nils
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Leinhard Dahlqvist, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Ekstedt, Mattias
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Diffuse Liver Disease: Measurements of Liver Trace Metal Concentrations and R2* Relaxation Rates2016Conference paper (Refereed)
    Abstract [en]

    Introduction

    Over the past decade, several methods for measuring of liver iron content (LIC) non-invasively with MRI have been developed and verified. The most promising methods uses relaxometry, measuring either R2- or R2* relaxation rate in the liver1,2. For instance, several studies have shown that there seems to be a linear relationship between R2* and LIC1. However, few of these studies have measured the liver content of other metals, which could also affect the relaxation rates. The goal of this study was to investigate if any trace metals, other than iron could affect the R2* relaxation rate in liver tissue in a patients with diffuse liver disease.

    Subjects and methods

    75 patients with suspected diffuse liver disease underwent an MRI examination followed by a liver biopsy the same day. The R2* relaxation rate of the water protons in the liver was measured using an axial 3D multi-slice fat-saturated multi-echo turbo field echo sequence (TE=4.60/9.20/13.80/18.40/23.00ms). Regions of interest (ROI) were drawn and R2* was estimated by fitting the mean signal intensity from the ROIs to a mono-exponential decay model. The biopsies were freeze dried and the concentrations of iron, manganese, copper, cobalt and gadolinium were measured using Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP-SFMS). A multiple linear regression analysis was applied to determine which of the measured metals significantly affected the relaxation rate.

    Results

    A linear regression with the LIC and R2* showed a reasonable fit (Figure 1). The multiple linear regression analysis (Table 1) showed that iron as well as manganese had a significant affect on R2*. Unlike iron however, the regression coefficient of manganese was negative, meaning that an increasing manganese concentration gave a shorter R2* relaxation rate. The same trend can be seen when plotting the manganese concentration against R2* (Figure 2).

  • 52.
    Kataria, Bharti
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Nilsson Althen, Jonas
    Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences.
    IMPLICATIONS OF PATIENT CENTRING ON ORGAN DOSE IN COMPUTED TOMOGRAPHY2016In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 169, no 1-4, p. 130-135Article in journal (Refereed)
    Abstract [en]

    Automatic exposure control (AEC) in computed tomography (CT) facilitates optimisation of dose absorbed by the patient. The use of AEC requires appropriate ‘patient centring’ within the gantry, since positioning the patient off-centre may affect both image quality and absorbed dose. The aim of this experimental study was to measure the variation in organ and abdominal surface dose during CTexaminations of the head, neck/thorax and abdomen. The dose was compared at the isocenter with two off-centre positions—ventral and dorsal to the isocenter. Measurements were made with an anthropomorphic adult phantom and thermoluminescent dosemeters. Organs and surfaces for ventral regions received lesser dose (5.6–39.0 %) than the isocenter when the phantom was positioned 13 cm off-centre. Similarly, organ and surface doses for dorsal regions were reduced by 5.0–21.0 % at 25 cm off-centre. Therefore, correct vertical positioning of the patient at the gantry isocenter is important to maintain optimal imaging conditions.

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  • 53.
    Kaveckyte, Vaiva
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Malusek, Alexandr
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Benmakhlouf, Hamza
    Karolinska Univ Hosp, Sweden.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Suitability of microDiamond detectors for the determination of absorbed dose to water around high-dose-rate Ir-192 brachytherapy sources2018In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 45, no 1, p. 429-437Article in journal (Refereed)
    Abstract [en]

    Purpose: Experimental dosimetry of high-dose-rate (HDR) Ir-192 brachytherapy (BT) sources is complicated due to high dose and dose-rate gradients, and softening of photon energy spectrum with depth. A single crystal synthetic diamond detector microDiamond (PTW 60019, Freiburg, Germany) has a small active volume, high sensitivity, direct readout, and nearly water-equivalent active volume. The purpose of this study was to evaluate the suitability of microDiamond detectors for the determination of absorbed dose to water around HDR Ir-192 BT sources. Three microDiamond detectors were used, allowing for the comparison of their properties. Methods: In-phantom measurements were performed using microSelectron and VariSource iX HDR Ir-192 BT treatment units. Their treatment planning systems (TPSs), Oncentra (v. 4.3) and BrachyVision (v. 13.6), respectively, were used to create irradiation plans for a cubic PMMA phantom with the microDiamond positioned at one of three source-to-detector distances (SDDs) (1.5, 2.5, and 5.5 cm) at a time. The source was stepped in increments of 0.5 cm over a total length of 6 cm to yield absorbed dose of 2 Gy at the nominal reference-point of the detector. Detectors were calibrated in Co-60 beam in terms of absorbed dose to water, and Monte Carlo (MC) calculated beam quality correction factors were applied to account for absorbed-dose energy dependence. Phantom correction factors were applied to account for differences in dimensions between the measurement phantom and a water phantom used for absorbed dose calculations made with a TPS. The same measurements were made with all three of the detectors. Additionally, dose-rate dependence and stability of the detectors were evaluated in Co-60 beam. Results: The percentage differences between experimentally determined and TPS-calculated absorbed doses to water were from -1.3% to +2.9%. The values agreed to within experimental uncertainties, which were from 1.9% to 4.3% (k = 2) depending on the detector, SDD and treatment delivery unit. No dose-rate or intrinsic energy dependence corrections were applied. All microDiamonds were comparable in terms of preirradiation dose, stability of the readings and energy response, and showed a good agreement. Conclusions: The results indicate that the microDiamond is potentially suitable for the determination of absorbed dose to water around HDR Ir-192 BT sources and may be used for independent verification of TPSs calculations, as well as for QA measurements of HDR Ir-192 BT treatment delivery units at clinical sites. (C) 2017 American Association of Physicists in Medicine

  • 54.
    Kaveckyte, Vaiva
    et al.
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Karolinska Univ Hosp, Sweden.
    Persson, Linda
    Swedish Radiat Safety Author, Sweden.
    Malusek, Alexandr
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Benmakhlouf, Hamza
    Karolinska Univ Hosp, Sweden.
    Alm Carlsson, Gudrun
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Health, Medicine and Caring Sciences, Division of Diagnostics and Specialist Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Karolinska Univ Hosp, Sweden.
    Investigation of a synthetic diamond detector response in kilovoltage photon beams2020In: Medical physics (Lancaster), ISSN 0094-2405Article in journal (Refereed)
    Abstract [en]

    Purpose An important characteristic of radiation dosimetry detectors is their energy response which consists of absorbed-dose and intrinsic energy responses. The former can be characterized using Monte Carlo (MC) simulations, whereas the latter (i.e., detector signal per absorbed dose to detector) is extracted from experimental data. Such a characterization is especially relevant when detectors are used in nonrelative measurements at a beam quality that differs from the calibration beam quality. Having in mind the possible application of synthetic diamond detectors (microDiamond PTW 60019, Freiburg, Germany) for nonrelative dosimetry of low-energy brachytherapy (BT) beams, we determined their intrinsic and absorbed-dose energy responses in 25-250 kV beams relative to a Co-60 beam, which is usually the reference beam quality for detector calibration in radiotherapy. Material and Methods Three microDiamond detectors and, for comparison, two silicon diodes (PTW 60017) were calibrated in terms of air-kerma free in air in six x-ray beam qualities (from 25 to 250 kV) and in terms of absorbed dose to water in a Co-60 beam at the national metrology laboratory in Sweden. The PENELOPE/penEasy MC radiation transport code was used to calculate the absorbed-dose energy response of the detectors (modeled based on blueprints) relative to air and water depending on calibration conditions. The MC results were used to extract the relative intrinsic energy response of the detectors from the overall energy response. Measurements using an independent setup with a single ophthalmic BEBIG I25.S16 I-125 BT seed (effective photon energy of 28 keV) were used as a qualitative check of the extracted intrinsic energy response correction factors. Additionally, the impact of the thickness of the active volume as well as the presence of extra-cameral components on the absorbed-dose energy response of a microDiamond detector was studied using MC simulations. Results The relative intrinsic energy response of the microDiamond detectors was higher by a factor of 2 in 25 and 50 kV beams compared to the Co-60 beam. The variation in the relative intrinsic energy response of silicon diodes was within 10% over the investigated photon energy range. The use of relative intrinsic energy response correction factors improved the agreement among the absorbed dose to water values determined using microDiamond detectors and silicon diodes, as well as with the TG-43 formalism-based calculations for the I-125 seed. MC study of microDiamond detector design features provided a possible explanation for inter-detector response variation at low-energy photon beams by differences in the effective thickness of the active volume. Conclusions MicroDiamond detectors had a non-negligible variation in the relative intrinsic energy response (factor of 2) which was comparable to that in the absorbed-dose energy response relative to water at low-energy photon beams. Silicon diodes, in contrast, had an absorbed-dose energy dependence on photon energy that varied by a factor of 6, whereas the intrinsic energy dependence on beam quality was within 10%. It is important to decouple these two responses for a full characterization of detector energy response especially when the user and reference beam qualities differ significantly, and MC alone is not enough.

    The full text will be freely available from 2020-12-27 08:12
  • 55.
    Koziorowski, Jacek
    et al.
    Linköping University, Department of Medical and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Stanciu, Adina E.
    Institute Oncology Prof Dr Al Trestioreanu Bucharest, Romania.
    Gomez-Vallejo, Vanessa
    CIC biomaGUNE, Spain.
    Llop, Jordi
    CIC biomaGUNE, Spain.
    Radiolabeled Nanoparticles for Cancer Diagnosis and Therapy2017In: ANTI-CANCER AGENTS IN MEDICINAL CHEMISTRY, ISSN 1871-5206, Vol. 17, no 3, p. 333-354Article, review/survey (Refereed)
    Abstract [en]

    Cancer remains as one of the major causes of death worldwide. The emergence of nanotechnology has opened new avenues for the development of nanoparticle (NP)-based diagnostic and therapeutic tools. NPs of different chemical composition, size, shape and surface decoration can be prepared using a wide variety of synthetic strategies. Subsequent radiolabelling with positron or gamma emitters results in potential diagnostic agents which may offer improved selectivity and/or specificity for the target organ or tissue, enabling the acquisition of images with higher signal-to-contrast ratio. Incorporation of alpha or beta emitters leads to therapeutic agents with application in the field of radiotherapy. Here, we first describe the different labeling strategies reported so far for the incorporation of radionuclides into NPs. Recent advances in the use of nanoparticulate constructs both in the diagnostic and therapeutic arenas are then discussed and examples of their application are briefly discussed.

  • 56.
    Labotka, R. J.
    et al.
    Department of Pediatrics, University of Illinois at Chicago, USA.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Pediatrics, University of Illinois at Chicago, USA.
    Kuchel, P. W.
    Department of Pediatrics, University of Illinois at Chicago, USA.
    Ammonia permeability of erythrocyte membrane studied by 14N and 15N saturation transfer NMR spectroscopy1995In: American Journal of Physiology - Cell Physiology, ISSN 0363-6143, E-ISSN 1522-1563, Vol. 268, no 3, p. C686-699Article in journal (Refereed)
    Abstract [en]

    The permeability of biological membranes to the rapidly penetrating compound ammonia is extremely difficult to study due to the lack of readily available radionuclides. 14N and 15N saturation transfer nuclear magnetic resonance (NMR) experiments were used to measure the erythrocyte membrane permeability of ammonia under equilibrium exchange conditions. When 14N spectra from erythrocytes suspended in NH4Cl solution were obtained in the presence of the extracellular shift reagent dysprosium tripolyphosphate, intracellular and extracellular ammonia signals were readily resolved. Comparison with 15N spectra from erythrocyte suspensions containing 15N4Cl revealed that the intracellular [14N]ammonia signals were 100% NMR visible. 14N and 15N saturation transfer NMR experiments showed similar influx rates and permeabilities, indicating no loss of saturation transfer due to quadrupolar relaxation of 14N nuclei upon membrane passage. Ammonia influx was directly proportional to concentration (0.39 +/- 0.012 fmol.cell-1.s-1.mM-1 at pH 7.0) and not saturable, which is consistent with passive diffusion. Apparent ammonia permeability increased with pH over the range of pH 6-8 as the fraction of free NH3 increased. However, diffusion through unstirred layers became increasingly rate limiting. The permeability of the unstirred layers (1.1 +/- 0.45 x 10(-3) cm/s) was considerably lower than that of NH3 (0.21 +/- 0.014 cm/s). The Arrhenius activation energy for NH3 permeability was 49.5 +/- 11.8 kJ/mol. No evidence for NH+4 influx over the time domain of these experiments was found.

  • 57.
    Lindborg, Lennart
    et al.
    Karolinska Institute, Sweden.
    Hultqvist, Martha
    RaySearch Labs, Sweden.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Swedish Radiat Safety Author, Sweden.
    Nikjoo, Hooshang
    Karolinska Institute, Sweden.
    Nanodosimetry and RBE values in radiotherapy2015In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 166, no 1-4, p. 339-342Article in journal (Refereed)
    Abstract [en]

    In a recent paper, the authors reported that the dose mean lineal energy, (y) over bar (D) in a volume of about 10-15 nm is approximately proportional to the alpha-parameter in the linear-quadratic relation used in fractionated radiotherapy in both low- and high-LET beams. This was concluded after analyses of reported radiation weighting factors, W-isoE (clinical RBE values), and (y) over bar (D) values in a large range of volumes. Usually, microdosimetry measurements in the nanometer range are difficult; therefore, model calculations become necessary. In this paper, the authors discuss the calculation method. A combination of condensed history Monte Carlo and track structure techniques for calculation of mean lineal energy values turned out to be quite useful. Briefly, the method consists in weighting the relative dose fractions of the primary and secondary charged particles with their respective energy-dependent dose mean lineal energies. The latter were obtained using a large database of Monte Carlo track structure calculations.

  • 58.
    Linge, Jennifer
    et al.
    AMRA Med AB, Linkoping, Sweden.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    West, Janne
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Tuthill, Theresa
    Pfizer Inc, MA USA.
    Miller, Melissa R.
    Pfizer Inc, MA USA.
    Dumitriu, Alexandra
    Pfizer Inc, MA USA.
    Thomas, E. Louise
    Univ Westminster, England.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    Tunon, Patrik
    AMRA Med AB, Linkoping, Sweden.
    Bell, Jimmy D.
    Univ Westminster, England.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    Body Composition Profiling in the UK Biobank Imaging Study2018In: Obesity, ISSN 1930-7381, E-ISSN 1930-739X, Vol. 26, no 11, p. 1785-1795Article in journal (Refereed)
    Abstract [en]

    ObjectiveMethodsThis study aimed to investigate the value of imaging-based multivariable body composition profiling by describing its association with coronary heart disease (CHD), type 2 diabetes (T2D), and metabolic health on individual and population levels. The first 6,021 participants scanned by UK Biobank were included. Body composition profiles (BCPs) were calculated, including abdominal subcutaneous adipose tissue, visceral adipose tissue (VAT), thigh muscle volume, liver fat, and muscle fat infiltration (MFI), determined using magnetic resonance imaging. Associations between BCP and metabolic status were investigated using matching procedures and multivariable statistical modeling. ResultsConclusionsMatched control analysis showed that higher VAT and MFI were associated with CHD and T2D (Pamp;lt;0.001). Higher liver fat was associated with T2D (Pamp;lt;0.001) and lower liver fat with CHD (Pamp;lt;0.05), matching on VAT. Multivariable modeling showed that lower VAT and MFI were associated with metabolic health (Pamp;lt;0.001), and liver fat was nonsignificant. Associations remained significant adjusting for sex, age, BMI, alcohol, smoking, and physical activity. Body composition profiling enabled an intuitive visualization of body composition and showed the complexity of associations between fat distribution and metabolic status, stressing the importance of a multivariable approach. Different diseases were linked to different BCPs, which could not be described by a single fat compartment alone.

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  • 59.
    Linge, Jennifer
    et al.
    Advanced MR Analytics AB, Linköping, Sweden.
    West, Janne
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Science & Engineering.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering.
    Bell, Jimmy
    Westminster University, London, UK.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    The Body Composition Profile – Enhancing the Understanding of Obesity using UK Biobank Imaging Data2017Conference paper (Refereed)
  • 60.
    Linge, Jennifer
    et al.
    Advanced MR Analytics AB, Linköping, Sweden.
    Whithcher, Brandon
    Advanced MR Analytics AB, Linköping, Sweden.
    Dimitriu, Alexandra
    Pfizer inc. Cambridge, MA, USA.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Associating Body Composition Profiling to Propensity for Diabetes2017Conference paper (Refereed)
  • 61.
    Lowén, Mats B. O.
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Mayer, E.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Tillisch, K.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Labus, J.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Naliboff, B.
    Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
    Lundberg, Peter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Thorell, Lars-Håkan
    Emotra AB, Gothenburg, Sweden.
    Ström, Magnus
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Engström, Maria
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Walter, Susanna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Deficient habituation to repeated rectal distensions in irritable bowel syndrome patients with visceral hypersensitivity2015In: Neurogastroenterology and Motility, ISSN 1350-1925, E-ISSN 1365-2982, Vol. 27, no 5, p. 646-655Article in journal (Refereed)
    Abstract [en]

    Background Irritable bowel syndrome (IBS) patients show evidence of altered central processing of visceral signals. One of the proposed alterations in sensory processing is an altered engagement of endogenous pain modulation mechanisms. The aim was to test the hypothesis that IBS patients with (IBS-S) and without visceral hypersensitivity (IBS-N) differ in their ability to engage endogenous pain modulation mechanism during habituation to repeated visceral stimuli.

    Methods Brain blood oxygen level dependent (BOLD) response was measured during repeated rectal distension and its anticipation in 33 IBS patients with and without visceral hypersensitivity and 18 healthy controls (HCs). BOLD response to early and late phase of the distension series was compared within and between groups.

    Key Results While BOLD response was similar during the early phase of the experiment, IBS-S showed greater BOLD response than IBS-N and HCs during the late phase of the distension series. IBS-S showed increasing BOLD response both to the anticipation and delivery of low intensity rectal distensions in brain regions including insula, anterior and mid cingulate cortex. IBS-N showed decreasing BOLD response to repeated rectal distensions in brain regions including insula, prefrontal cortex and amygdala.

    Conclusions & Inferences These findings are consistent with compromised ability of IBS-S to respond to repeated delivery of rectal stimuli, both in terms of sensitization of sensory pathways and habituation of emotional arousal. The fact that both IBS subgroups met Rome criteria, and did not differ in terms of reported symptom severity demonstrates that similar symptom patterns can result from different underlying neurobiological mechanisms.

  • 62.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Educational NMR software1997In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 74, no 12, p. 1489-1491Article in journal (Refereed)
    Abstract [en]

    A description of a compilation of computer programs (EduNMRSoft) suitable for teaching NMR at an introductory to advanced level is presented. Each program is categorised and described by function, hardware requirements, availability, author, and references in the list. The compilation is available in electronic form at http://www.chem.umu.se/divisions/fk/EduNMRSoft.html.

  • 63.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biochemistry, University of Sydney, Sydney, New South Wales. 2006, Australia.
    Berners-Price, Susan J.
    Division of Science and Technology, Griffith University, Nathan, Queensland, 4111, Australia.
    Roy, Sushmita
    Department of Biochemistry, University of Sydney, Sydney, New South Wales. 2006, Australia.
    Kuchel, Philip W.
    Department of Biochemistry, University of Sydney, Sydney, New South Wales. 2006, Australia.
    NMR studies of erythrocytes immobilized in agarose and alginate gels1992In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Magn Reson Med, Vol. 25, no 2, p. 273-288Article in journal (Refereed)
    Abstract [en]

    31P and 13C NMR were used to study the energy metabolism in perfused, human erythrocytes. The erythrocytes were immobilized in agarose threads, Ca- or Ba-alginate beads, and Ba-alginate-coated agarose threads. Erythrocytes were easily washed out from the agarose threads, but not from alginate-containing gels. Various small molecules, such as hypophosphite, dimethyl methylphosphonate, and methylphosphonate, were taken up from the perfusion medium in a normal manner. In addition, the 2,3-bisphosphoglycerate (2,3-DPG) chemical shifts were sensitive to the oxygen partial pressure suggesting that O2 molecules were diffusing through the gel and modifying the binding of 2,3-DPG to hemoglobin. A combination of inosine and pyruvate stimulated the synthesis of 2,3-DPG, but only if inorganic phosphate was present in the perfusion medium. Inosine only resulted in a dramatic rise in the intracellular sugarphosphate concentrations. Furthermore, [2-13C]glucose was converted to [2-13C]lactate by immobilized cells at a rate which was comparable to that in a control suspension. In summary, immobilization in Ba-alginate-coated agarose threads was an efficient way of trapping human erythrocytes for whole cell NMR investigations.

  • 64.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biochemistry, University of Sydney, Australia.
    Dudman, Nicholas P.
    Department of Cardiovascular Medicine, Prince Henry Hospital, University of New South Wales, Australia.
    Kuchel, Philip W.
    Department of Biochemistry, University of Sydney, Australia.
    Wilcken, David E. L.
    Present address: Department of Physical Chemistry, University of Umeå, Umeå, Sweden.
    1H NMR determination of urinary betaine in patients with premature vascular disease and mild homocysteinemia1995In: Clinical Chemistry, ISSN 0009-9147, E-ISSN 1530-8561, Vol. 41, no 2, p. 275-283Article in journal (Refereed)
    Abstract [en]

    Urinary N,N,N-trimethylglycine (betaine) and N,N-dimethylglycine (DMG) have been identified and quantified for clinical purposes by proton nuclear magnetic resonance (1H NMR) measurement in previous studies. We have assessed these procedures by using both one-dimensional (1-D) and 2-D NMR spectroscopy, together with pH titration of urinary extracts to help assign 1H NMR spectral peaks. The betaine calibration curve linearity was excellent (r = 0.997, P = 0.0001) over the concentration range 0.2-1.2 mmol/L, and CVs for replicate betaine analyses ranged from 7% (n = 10) at the lowest concentration to 1% (n = 9) at the highest. The detection limit for betaine was < 15 mumol/L. Urinary DMG concentrations were substantially lower than those of betaine. Urinary betaine and DMG concentrations measured by 1H NMR spectroscopy from 13 patients with premature vascular disease and 17 normal controls provided clinically pertinent data. We conclude that 1H NMR provides unique advantages as a research tool for determination of urinary betaine and DMG concentrations.

  • 65.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    van Ettinger-Veenstra, Helene
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Pain disrupts thalamic and nucleus accumbens functional connectivity in chronic widespread pain2016Conference paper (Refereed)
  • 66.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Forsgren, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Nasr, Patrik
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Ignatova, Simone
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Leinhard Dahlqvist, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Dahlström, Nils
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Ekstedt, Mattias
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Kvantifiering av leversteatos: diagnostisk utvärdering av protonmagnetresonansspektroskopi jämfört med histologiska metoder2016Conference paper (Refereed)
    Abstract [sv]

    Bakgrund

    Leversteatos är den vanligaste manifestationen av leversjukdom i västvärlden. Leverbiopsi med semikvantitativ histologisk gradering är referensmetod vid gradering av leversteatos. Med protonmagnetsresonansspektroskopi (1H-MRS), en metod som föreslagits ersätta leverbiopsi för värdering av steatos, kan leverns innehåll av triglycerider mätas icke-invasivt. Triglyceridinnehåll >5,00 % används ofta som ett diagnostiskt kriterium för leversteatos vid undersökning med 1H-MRS. Syftet med studien var att jämföra 1H-MRS med semikvantitativ histologisk steatosgradering och kvantitativ histologisk steatosmätning.

    Metod

    Patienter remitterade för utredning av förhöjda leverenzymer in-kluderades i studien. Samtliga patienter genomgick klinisk undersökning, laboratorieprovtagning samt 1H-MRS direkt följd av leverbiopsi. För konventionell histologisk semikvantitativ gradering av steatos användes kriterierna utarbetade av Brunt och medarbetare. Kvantitativ mätning av fett i biopsierna utfördes genom att med hjälp av stereologisk punkträkning (SPC) mäta andelen av ytan som innehöll fettvakuoler.

    Resultat

    I studien inkluderades 94 patienter, varav 37 hade icke-alkoholor-sakad fettleversjukdom (NAFLD), 49 hade andra leversjukdomar och 8 hade normal leverbiopsi. En stark korrelation noterades mel-lan 1H-MRS och SPC (r=0,92, p<0,0001; к=0.82). Korrelationen mellan 1H-MRS och Brunts kriterier (к=0.26) samt mellan SPC och Brunts kriterier (к=0.38) var betydligt sämre. När patologens gradering (Brunts kriterier) användes som referensmetod för diag-nos av leversteatos så hade alla patienter med triglyceridinnehåll >5,00 % mätt med 1H-MRS steatos (specificitet 100 %). Emellertid hade 22 av 69 patienter med triglyceridinnehåll ≤5,00 % också le-versteatos enligt Brunts kriterier (sensitivitet 53 %). Motsvarande siffror när man använde gränsvärdet 3,02 % var sensitivitet 79 % och specificitet 100 %. Vid ytterligare reduktion av gränsvärdet för triglyceridinnehåll till 2,00 % ökade sensitiviteten till 87 % med upprätthållande av hög specificitet (94 %).

    Slutsats

    1H-MRS och SPC uppvisade en mycket hög korrelation vid kvantifiering av leversteatos. SPC borde därför föredras framför Brunts kriterier när noggrann histologisk kvantifiering av leversteatos är önskvärd. Många patienter kan ha histologisk leversteatos trots triglyceridinnehåll ≤5,00 % mätt med 1H-MRS. Gränsvärdet för diagnostisering av leversteatos med 1H-MRS bör därför reduceras.

  • 67.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Harmsen, Eef
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Ho, Clinton
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Vogel, Hans J.
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Nuclear magnetic resonance studies of cellular metabolism1990In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 191, no 2, p. 193-222Article in journal (Refereed)
    Abstract [en]

    Nuclear magnetic resonance (NMR) spectroscopy was described in 1946 (1,2), initially as a method that had appeal only for nuclear physicists who used it to accurately determine nuclear magnetic moments. Thissituation changed rapidly, however, when it was demonstrated that the NMR frequency for the same nucleus in different chemical compounds was different (3). For example, two separate signals are observed in a 14N NMR spectrum of a solution of NH,NO,, representing the NH: and NO; ions, respectively (4). Since individual atoms within one molecule also give rise to resolved signals (5) it became clear that the NMR technique held great analytical potential, in particular since the spectra can be recorded in such a way that the area under a signal is directly proportional to its concentration. Such phenomena and various theoretical aspects of NMR are currently quite well understood (6,7). Because of these features NMR has become the foremost spectroscopic method for the analysis of all sorts of chemical compounds.

  • 68.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Icenhour, Adriane
    Bednarska, O.
    Tapper, Sofie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Witt, ST
    Elsenbruch, S
    Walter, Susanna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Increased inhibitory neurotransmission within anterior cingulate cortex is related to comorbid anxiety in irritable bowel syndrome.2016Conference paper (Other academic)
  • 69.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Karlsson, Markus
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Forsgren, Mikael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Dahlström, Nils
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Leinhard Dahlqvist, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Cedersund, Gunnar
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Ekstedt, Mattias
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Mechanistic modeling of qDCE-MRI data reveals increased bile excretion of Gd-EOB-DTPA in diffuse liver disease patients with severe fibrosis2016Conference paper (Refereed)
    Abstract [en]

    Introduction

    Over the past decades, several different non-invasive methods for staging hepatic fibrosis have been proposed. One such method is dynamic contrast enhanced MRI (DCE-MRI) using the contrast agent (CA) Gd-EOB-DTPA. Gd-EOB-DTPA is liver specific, which means that it is taken up specifically by the hepatocytes via the OATP3B1/B3 transporters and excreted into the bile via the MRP2 transporter. Several studies have shown that DCE-MRI and Gd-EOBDTPA can separate patients with advanced (F3-F4) from mild (F0-F2) hepatic fibrosis by measuring the signal intensity, where patients with advanced fibrosis have a lower signal intensity than the mild fibrosis cases.1 However, none of the studies up to date have been able to differentiate if the reduced signal intensity in the liver is because of an decreased uptake of CA or an increased excretion. Analyzing the DCE-MRI data with mechanistic mathematical modelling has the possibility of investigating such a differentiation.

    Subjects and methods

    88 patients with diffuse liver disease were examined using DCE-MRI (1.5 T Philips Achieva, two-point Dixon, TR=6.5 ms, TE=2.3/4.6 ms, FA=13) after a bolus injection of Gd-EOB-DTPA, followed by a liver biopsy. Regions of interest were placed within the liver, spleen and veins and a whole-body mechanistic pharmacokinetic model2 was fitted to the data. The fitted parameters in the model correspond to the rate of CA transport between different compartments, e.g. hepatocytes, blood plasma, and bile (Fig. 1).

    Results

    As can be seen in Fig. 2, the parameter corresponding to the transport of CA from the blood plasma to the hepatocytes, kph, is lower for patients with advanced fibrosis (p=0.01). Fig. 3 shows that the parameter corresponding to the CA excretion into the bile, khb, is higher for patients with advanced fibrosis (p<0.01).

    Discussion/Conclusion

    This work shows that the decreased signal intensity in DCE-MRI images in patients with advanced fibrosis depends on both a decreased uptake of CA in the hepatocytes and an increased excretion into the bile. Similar results have also been observed in a rat study3. In that study, rats with induced cirrhosis had a higher MRP2-activity than the healthy control rats.

    References

    1Norén et al: Eur. Radiol, 23(1), 174-181, 2013.

    2Forsgren et al: PloS One, 9(4): e95700, 2014.

    3Tsuda & Matsui: Radiol, 256(3): 767-773, 2010.

  • 70.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Physical Chemistry, University of Umeå, Umeå, Sweden / Department of Biochemistry, University of Sydney, Australia .
    Kuchel, Philip W.
    Department of Physical Chemistry, University of Umeå, Umeå, Sweden / Department of Biochemistry, University of Sydney, Australia.
    Diffusion of solutes in agarose and alginate gels: 1H and 23Na PFGSE and 23Na TQF NMR studies1997In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 37, no 1, p. 44-52Article in journal (Refereed)
    Abstract [en]

    Cells immobilized in gels experience potential metabolic restrictions in the form of reduced diffusion rates of metabolites and ions and their possible selective adsorption on the gel matrix. Diffusion and relaxation characteristics of common solutes in agarose and barium alginate gels were investigated at 37 degrees C by using 1H PFGSE and 23Na TQF NMR spectroscopy. Glucose, glycine, alanine, lactate, sodium ions, and HDO were studied. There were no selective interactions between any of the metabolites and the gel materials but the diffusion coefficients were uniformly reduced. The effects of metabolite diffusion and utilization, in gel beads and threads containing cells, were simulated by using a reaction diffusion model incorporating the measured diffusion coefficients. Metabolism is expected to be very significantly limited by diffusion of solutes to and from the cells that are centrally located within gel threads or spheres of radius approximately 2.0 mm, which is a commonly used size.

  • 71.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biochemistry, University of Sydney, Australia..
    Roy, Sushmita
    Department of Biochemistry, University of Sydney, Australia..
    Kuchel, Philip W.
    Department of Biochemistry, University of Sydney, Australia..
    Fructose 3-phosphate and 5-phosphoribosyl-1-pyrophosphate formation in perfused human erythrocytes: 31P NMR studies1994In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 31, no 2, p. 110-121Article in journal (Refereed)
    Abstract [en]

    31P NMR was used to study the formation of fructose 3-phos-phate (F3P) and 5-phosphoribosyl-1-pyrophosphate (PRPP) in perfused human erythrocytes, in the presence of 10 different combinations and concentrations of glucose, inosine, pyru-vate, fructose, and inorganic phosphate (Pi). (1) The cells were immobilized in alginate-coated agarose threads and perfused with a medium containing fructose, and the level of F3P increased continuously over more than 10 h. The net rate of F3P formation was independent of the concentration of 2,3-bis-phosphoglycerate (2,3-DPG) present in the cells. (2) PRPP was formed in high concentrations, relative to normal, in immobilized cells when they were perfused with a medium containing Pi at a low pH (6.6). (3) The 2,3-DPG level decreased simultaneously when the sample was perfused with a medium containing fructose, but without inosine or pyruvate. The measured intracellular pH and free Mg2+ concentration were constant in these experiments. (4) The experiments confirmed the presence of fructose-3-phosphokinase (E.C. 2.7.1.-) and ribose-phosphate pyrophosphokinase (E.C. 2.7.6.1) activity in the human erythrocytes and that the biosynthetic pathways are active in immobilized cells at 37°C. (5) The rates of accumulation of 2,3-DPG and phosphomonoesters (PME) appeared to be strongly correlated.

  • 72.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Quantification of metabolite relaxation rates using STEAM2016Conference paper (Refereed)
  • 73.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Subject movements in MRS: Evaluating the reliability in GABA concentrations determined at 3 T.2016Conference paper (Refereed)
  • 74.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Cedersund, Gunnar
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Shimekaw, Sara
    Robust Quantification of Myelin Water Volume and Water Exchange2016Conference paper (Refereed)
  • 75.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Tapper, Sofie
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Absolute Quantification of Metabolite Concentrations and Relaxation Rates.2016Conference paper (Refereed)
  • 76.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Physical Chemistry 2, University of Lund, 221 000 Lund, Sweden.
    Vogel, Hans J.
    Department of Physical Chemistry 2, University of Lund, 221 000 Lund, Sweden.
    Post-mortem metabolism in fresh porcine, ovine and frozen bovine muscle1987In: Meat Science, ISSN 0309-1740, E-ISSN 1873-4138, Vol. 19, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Post-mortem metabolism was followed by phosphorus-31-NMR in muscle samples obtained from freshly slaughtered pigs and lambs. Resonances for creatine phosphate (CP), ATP, inorganic phosphate (Pi) and sugar phosphates (SP) could be discerned and the intracellular pH could be determined from the spectra. The rates of post-mortem metabolism varied in the following fashion: porcine muscle > ovine muscle > bovine muscle. However, the course of post-mortem metabolism was, in all cases, the same. CP disappeared first and then ATP. Simultaneously, Pi increased, while SP remained relatively constant. The intracellular pH decreased to pH 5·5 in all tissues.

    In a separate set of experiments the post-mortem metabolism during thawing was studied in bovine muscles that had been frozen immediately after slaughter. Again, the same course of post-mortem metabolism was observed, but the thaw shortening was accompanied by an extremely rapid post-mortem metabolism, which was more than ten times as fast as that measured for fresh bovine muscles. The intracellular pH decreased from 7·2 to 5·5 in 45 min. This rapid metabolism started only after the sample ha reached 0°C. Resonances for metabolites were broadened in frozen muscles due to the limited motions that are allowed within the ice lattice.

  • 77.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Vogel, Hans J.
    Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Brodelius, Peter E.
    Department of Plant Biochemistry, Lund University, Lund, Sweden.
    A phosphorus-31 nuclear magnetic resonance study of elicitor-mediated metabolic changes in Catharanthus roseus suspension cultures1997In: In vitro cellular & developmental biology. Plant, ISSN 1054-5476, E-ISSN 1475-2689, Vol. 33, no 4, p. 301-305Article in journal (Refereed)
    Abstract [en]

    The induction of metabolic changes in suspension cultured cells of Catharanthus roseus upon elicitation has been investigated. Addition of a yeast glucan preparation to the growth medium resulted in induction of phenylalanine ammonia lyase. Phosphate uptake and metabolism of elicited cells was followed by 31P nuclear magnetic resonance. The uptake rate of Pi from the medium by oxygenated cells of C. roseus was reduced immediately after elicitation. Despite this reduced Pi uptake elicited cells had significantly increased amounts of ATP (twofold increase within 6 h). Cytoplasmic levels of Pi, phosphomonoesters, and Uridine Diphasphate glucose (UDP-Glc) were unaffected by eliciation. Furthermore, the cytoplasmic and vacuolar pH remained constant after addition of elicitor.

  • 78.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Department of Biological Sciences, University of Calgary, Calgary Canada.
    Vogel, Hans J.
    Department of Biological Sciences, University of Calgary, Calgary Canada.
    Drakenberg, Torbjörn
    Department of Physical Chemistry 2, University of Lund, Lund Sweden.
    Forsén, Sture
    Department of Physical Chemistry 2, University of Lund, Lund Sweden.
    Amiconi, Gino
    CNR Center of Molecular Biology and Department of Biochemical Sciences, Rome Italy.
    Forlani, Luciano
    Department of Experimental Medicine, University ‘La Sapienza’, Rome Italy.
    Chiancone, Emilia
    CNR Center of Molecular Biology and Department of Biochemical Sciences, Rome Italy.
    A35Cl--NMR study of the singular anion-binding properties of dromedary hemoglobin1989In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 999, no 1, p. 12-8Article in journal (Refereed)
    Abstract [en]

    35Cl(-)-NMR measurements of chloride binding to carbonmonoxy- and deoxy-dromedary hemoglobin reveal the existence of two classes of chloride-binding sites, one of high and the other of low affinity. Although this situation resembles that described for human hemoglobin, it was found that the number of binding sites as well as the association equilibrium constant for chloride binding are significantly higher in the dromedary protein. This difference may be due to the greater number of basic residues exposed to solvent and to the higher flexibility of dromedary hemoglobin. The two oxygen-linked polyanion-binding sites characteristic of this hemoglobin show competition for some of the high-affinity chloride-binding sites in keeping with their location in the cleft enclosed by the beta chains and between the alpha chains termini. It is suggested that the observed anion-binding properties of dromedary hemoglobin may contribute to the control of the physiological osmotic shock after rehydration.

  • 79.
    Lundberg, Peter
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Weich, Rainer. G.
    Jensen, Paul.
    Vogel, Hans J.
    Phosphorus-31 and Nitrogen- 14 NMR Studies of the Uptake of Phosphorus and Nitrogen Compounds in the Marine Macroalgae Ulva lactuca1989In: Plant Physiology, ISSN 0032-0889, E-ISSN 1532-2548, Vol. 89, no 4, p. 1380-1387Article in journal (Refereed)
    Abstract [en]

    Cytoplasmic phosphomonoesters and inorganic phosphate, as well as vacuolar inorganic phosphate and polyphosphates, gave rise to the major peaks in (31)P nuclear magnetic resonance (NMR) spectra of the marine macroalgae Enteromorpha sp., Ceramium sp., and Ulva lactuca which were collected from the sea. In contrast, NMR-visible polyphosphates were lacking in Pylaiella sp. and intracellular vacuolar phosphate seemed to act as the main phosphorus store in this organism. In laboratory experiments, polyphosphates decreased in growing U. lactuca which was cultivated in continuous light under phosphate-deficient conditions. In contrast, the same organism cultivated in seawater with added phosphate and ammonium, accumulated phosphate mainly in the form of polyphosphates. When nitrate was provided as the only nitrogen source, accumulation of polyphosphates in the algae decreased with increasing external nitrate concentration. From the chemical shift of the cytoplasmic Pi peak, the cytoplasmic pH of superfused preparations of Ulva was estimated at 7.2. The vacuolar pH, determined from the chemical shifts of the vacuolar Pi and the terminal polyphosphate peaks, was between 5.5 and 6.0. The intracellular nitrate and ammonium levels in U. lactuca were determined by (14)N NMR. Both nitrogen sources were taken up and stored intracellularly; however, the uptake of ammonium was much faster than that of nitrate.

  • 80.
    Ma, Yunzhi
    et al.
    CHU Quebec, Canada; University of Laval, Canada; University of Laval, Canada.
    Vijande, Javier
    University of Valencia, Spain; IFIC, Spain.
    Ballester, Facundo
    University of Valencia, Spain.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Karolinska University Hospital, Sweden.
    Granero, Domingo
    Hospital Gen University, Spain.
    Haworth, Annette
    University of Sydney, Australia.
    Mourtada, Firas
    Christiana Care Health Syst, DE 19713 USA; Christiana Care Health Syst, DE 19713 USA.
    Paiva Fonseca, Gabriel
    Maastricht University, Netherlands.
    Zourari, Kyveli
    University of Athens, Greece.
    Papagiannis, Panagiotis
    University of Athens, Greece.
    Rivard, Mark J.
    Tufts University, MA 02111 USA.
    Siebert, Frank-Andre
    University Hospital Schleswig Holstein, Germany.
    Sloboda, Ron S.
    Cross Cancer Institute, Canada; University of Alberta, Canada.
    Smith, Ryan
    Alfred Hospital, Australia.
    Chamberland, Marc J. P.
    Carleton University, Canada.
    Thomson, Rowan M.
    Carleton University, Canada.
    Verhaegen, Frank
    Maastricht University, Netherlands.
    Beaulieu, Luc
    CHU Quebec, Canada; University of Laval, Canada; University of Laval, Canada.
    A generic TG-186 shielded applicator for commissioning model-based dose calculation algorithms for high-dose-rate Ir-192 brachytherapy2017In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 44, no 11, p. 5961-5976Article in journal (Refereed)
    Abstract [en]

    PurposeA joint working group was created by the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) with the charge, among others, to develop a set of well-defined test case plans and perform calculations and comparisons with model-based dose calculation algorithms (MBDCAs). Its main goal is to facilitate a smooth transition from the AAPM Task Group No. 43 (TG-43) dose calculation formalism, widely being used in clinical practice for brachytherapy, to the one proposed by Task Group No. 186 (TG-186) for MBDCAs. To do so, in this work a hypothetical, generic high-dose rate (HDR) Ir-192 shielded applicator has been designed and benchmarked. MethodsA generic HDR Ir-192 shielded applicator was designed based on three commercially available gynecological applicators as well as a virtual cubic water phantom that can be imported into any DICOM-RT compatible treatment planning system (TPS). The absorbed dose distribution around the applicator with the TG-186 Ir-192 source located at one dwell position at its center was computed using two commercial TPSs incorporating MBDCAs (Oncentra((R)) Brachy with Advanced Collapsed-cone Engine, ACE, and BrachyVision ACUROS) and state-of-the-art Monte Carlo (MC) codes, including ALGEBRA, BrachyDose, egs_brachy, Geant4, MCNP6, and Penelope2008. TPS-based volumetric dose distributions for the previously reported source centered in water and source displaced test cases, and the new source centered in applicator test case, were analyzed here using the MCNP6 dose distribution as a reference. Volumetric dose comparisons of TPS results against results for the other MC codes were also performed. Distributions of local and global dose difference ratios are reported. ResultsThe local dose differences among MC codes are comparable to the statistical uncertainties of the reference datasets for the source centered in water and source displaced test cases and for the clinically relevant part of the unshielded volume in the source centered in applicator case. Larger local differences appear in the shielded volume or at large distances. Considering clinically relevant regions, global dose differences are smaller than the local ones. The most disadvantageous case for the MBDCAs is the one including the shielded applicator. In this case, ACUROS agrees with MC within [-4.2%, +4.2%] for the majority of voxels (95%) while presenting dose differences within [-0.12%, +0.12%] of the dose at a clinically relevant reference point. For ACE, 95% of the total volume presents differences with respect to MC in the range [-1.7%, +0.4%] of the dose at the reference point. ConclusionsThe combination of the generic source and generic shielded applicator, together with the previously developed test cases and reference datasets (available in the Brachytherapy Source Registry), lay a solid foundation in supporting uniform commissioning procedures and direct comparisons among treatment planning systems for HDR Ir-192 brachytherapy.

  • 81.
    Magnusson, Maria
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Diagnostics, Medical radiation physics.
    Björnfot, Magnus
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Medical radiation physics.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Medical radiation physics. Karolinska Univ, Sweden.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Medical radiation physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Malusek, Alexandr
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    DIRA-3D-a model-based iterative algorithm for accurate dual-energy dual-source 3D helical CT2019In: BIOMEDICAL PHYSICS and ENGINEERING EXPRESS, ISSN 2057-1976, Vol. 5, no 6, article id UNSP 065005Article in journal (Refereed)
    Abstract [en]

    Quantitative dual-energy computed tomography may improve the accuracy of treatment planning in radiation therapy. Of special interest are algorithms that can estimate material composition of the imaged object. One example of such an algorithm is the 2D model-based iterative reconstruction algorithm DIRA. The aim of this work is to extend this algorithm to 3D so that it can be used with cone-beams and helical scanning. In the new algorithm, the parallel FBP method was replaced with the approximate 3D FBP-based PI-method. Its performance was tested using a mathematical phantom consisting of six ellipsoids. The algorithm substantially reduced the beam-hardening artefact and the artefacts caused by approximate reconstruction after six iterations. Compared to Alvarez-Macovskis base material decomposition, DIRA-3D does not require geometrically consistent projections and hence can be used in dual-source CT scanners. Also, it can use several tissue-specific material bases at the same time to represent the imaged object.

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  • 82.
    Malusek, Alexandr
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Magnusson, Maria
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    A model-based iterative reconstruction algorithm DIRA using patient-specific tissue classification via DECT for improved quantitative CT in dose planning2017In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 44, no 6, p. 2345-2357Article in journal (Refereed)
    Abstract [en]

    Purpose: To develop and evaluate-in a proof-of-concept configuration-a novel iterative reconstruction algorithm (DIRA) for quantitative determination of elemental composition of patient tissues for application to brachytherapy with low energy (amp;lt; 50 keV) photons and proton therapy. Methods: DIRA was designed as a model-based iterative reconstruction algorithm, which uses filtered backprojection, automatic segmentation and multimaterial tissue decomposition. The evaluation was done for a phantom derived from the voxelized ICRP 110 male phantom. Soft tissues were decomposed to the lipid, protein and water triplet, bones were decomposed to the compact bone and bone marrow doublet. Projections were derived using the Drasim simulation code for an axial scanning configuration resembling a typical DECT (dual-energy CT) scanner with 80 kV and Sn140 kV x-ray spectra. The iterative loop produced mono-energetic images at 50 and 88 keV without beam hardening artifacts. Different noise levels were considered: no noise, a typical noise level in diagnostic imaging and reduced noise level corresponding to tenfold higher doses. An uncertainty analysis of the results was performed using type A and B evaluations. The two approaches were compared. Results: Linear attenuation coefficients averaged over a region were obtained with relative errors less than 0.5% for all evaluated regions. Errors in average mass fractions of the three-material decomposition were less than 0.04 for no noise and reduced noise levels and less than 0.11 for the typical noise level. Mass fractions of individual pixels were strongly affected by noise, which slightly increased after the first iteration but subsequently stabilized. Estimates of uncertainties in mass fractions provided by the type B evaluation differed from the type A estimates by less than 1.5% for most cases. The algorithm was fast, the results converged after 5 iterations. The algorithmic complexity of forward polyenergetic projection calculation was much reduced by using material doublets and triplets. Conclusions: The simulations indicated that DIRA is capable of determining elemental composition of tissues, which are needed in brachytherapy with low energy (amp;lt; 50 keV) photons and proton therapy. The algorithm provided quantitative monoenergetic images with beam hardening artifacts removed. Its convergence was fast, image sharpness expressed via the modulation transfer function was maintained, and image noise did not increase with the number of iterations. c 2017 American Association of Physicists in Medicine

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  • 83.
    Malusek, Alexandr
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    ACCURATE KAP METER CALIBRATION AS A PREREQUISITE FOR OPTIMISATION IN PROJECTION RADIOGRAPHY2016In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 169, no 1-4, p. 353-359Article in journal (Refereed)
    Abstract [en]

    Modern X-ray units register the air kerma–area product, PKA, with a built-in KAP meter. Some KAP meters show an energydependent bias comparable with the maximum uncertainty articulated by the IEC (25 %), adversely affecting dose-optimisation processes. To correct for the bias, a reference KAP meter calibrated at a standards laboratory and two calibration methods described here can be used to achieve an uncertainty of <7 % as recommended by IAEA. A computational model of the reference KAP meter is used to calculate beam quality correction factors for transfer of the calibration coefficient at the standards laboratory, Q0, to any beam quality, Q, in the clinic. Alternatively, beam quality corrections are measured with an energy-independent dosemeter via a reference beam quality in the clinic, Q1, to beam quality, Q. Biases up to 35 % of built-in KAP meter readings were noted. Energy-dependent calibration factors are needed for unbiased PKA. Accurate KAP meter calibration as a prerequisite for optimisation in projection radiography.

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  • 84.
    Marcu, Loredana G.
    et al.
    University of Oradea, Romania and University of Adelaide, Australia.
    Bezak, Eva
    Royal Adelaide Hospital, Australia.
    Toma-Dasu, Iuliana
    Stockholm University and Karolinska Institutet, Sweden.
    Dasu, Alexandru
    Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences.
    Predictive models of tumour response to treatment using functional imaging techniques2015In: Computational & Mathematical Methods in Medicine, ISSN 1748-670X, E-ISSN 1748-6718, Vol. 2015, p. Article ID 571351-Article in journal (Other academic)
  • 85.
    McIntyre, Deane D.
    et al.
    Departments of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Apblett, Allen W.
    Department of Chemistry, University of Calgary, Calgary, Alberta, Canada.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Departments of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Schmidt, Kenneth J.
    Department of Chemistry, University of Calgary, Calgary, Alberta, Canada .
    Vogel, Hans J.
    Departments of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
    Nitrogen-14 NMR relaxation, and reorientation behavior of dissolved dinitrogen1989In: Journal of magnetic resonance, ISSN 1090-7807, E-ISSN 1096-0856, Vol. 83, no 2, p. 377-382Article in journal (Refereed)
    Abstract [en]

    In recent years, nitrogen- 14 and - 15 NMR spectroscopy has become an important technique in organic chemistry and in biochemistry ( Z-4). A frequent occurrence in the NMR spectra of both nuclei is the presence of a signal at approximately -7 1.5ppm (referred to neat nitromethane; -66 ppm referred to aqueous nitrate). This resonance, which has been observed in water (4) and a range of organic solvents (.5-7), has been the subject of some confusion in the literature. In the case of nitrogen-14 NMR spectra, the signal for the quadrupolar nucleus has a remarkably narrow linewidth (about 25 Hz) compared to those recorded for a wide variety of other substances. This indicates a fairly high degree of electronic symmetry about the nitrogenatom and/or a very short correlation time ( 7,). In a recent report (8)) this signal has been assigned to dissolved dinitrogen on the basis that it could be removed by degassing´the solution; however, no reference was made to the fact that it had a remarkably narrow linewidth compared to other 14N NMR resonances. When detected in the 15NCIDNP spectra of the decomposition products of diazonium ions (5, 6) as well as azo compounds ( 7)) the signal has been assigned either to dinitrogen (6, 7) or to a terminal diazonium nitrogen (5). This work is in general agreement with our own observations over a period of years which indicate that the signal arises from dissolved dinitrogen. We have measured the 14N chemical shift of dissolved N2 in a number of solvents at 25°C and have also determined the T, and T2 relaxation times under a variety of conditions in solvents of different viscosity. This Note is concerned with a discussion of these 14N NMR observations and with the determination of the correlation time of dissolved dinitrogen which permits the determination of both the enthalpy and the entropy of activation via the Eyring equation. These results will be compared with earlier reported data regarding the chemical shift and relaxation of liquid nitrogen obtained under a variety of conditions ( 9-12). All spectra were obtained on a Bruker AM-400 wide-bore NMR spectrometer operating in the FT mode at a frequency of 28.9 MHz for 14N and 40.5 MHz for 15N, using a 10 mm broadband probe. Typical conditions for the acquisition of 14N spectra

  • 86.
    Mellergård, Johan
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Neurology.
    Tisell, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Blystad, Ida
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Grönqvist, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Blennow,, K.
    Clinical Neurochemistry Laboratory, Institution of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Sweden.
    Olsson,, B.
    Clinical Neurochemistry Laboratory, Institution of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg.
    Dahle, Charlotte
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Vrethem, Magnus
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Neurology. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Clinical Neurophysiology.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Ernerudh, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Cerebrospinal fluid levels of neurofilament and tau correlate with brain atrophy in natalizumab-treated multiple sclerosis2017In: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 24, no 1, p. 112-121Article in journal (Refereed)
    Abstract [en]

    Background and purpose

    Brain atrophy is related to clinical deterioration in multiple sclerosis (MS) but its association with intrathecal markers of inflammation or neurodegeneration is unclear. Our aim was to investigate whether cerebrospinal fluid (CSF) markers of inflammation or neurodegeneration are associated with brain volume change in natalizumab-treated MS and whether this change is reflected in non-lesional white matter metabolites.

    Methods

    About 25 patients with natalizumab-treated MS were followed for 3 years with assessment of percentage brain volume change (PBVC) and absolute quantification of metabolites with proton magnetic resonance spectroscopy (1H MRS). Analyses of inflammatory [interleukin 1β (IL-1β), IL-6, C-X-C motif chemokine 8 (CXCL8), CXCL10, CXCL11, C-C motif chemokine 22] and neurodegenerative [neurofilament light protein (NFL), glial fibrillary acidic protein, myelin basic protein, tau proteins] markers were done at baseline and 1-year follow-up.

    Results

    The mean decline in PBVC was 3% at the 3-year follow-up, although mean 1H MRS metabolite levels in non-lesional white matter were unchanged. CSF levels of NFL and tau at baseline correlated negatively with PBVC over 3 years (r = −0.564, P = 0.012, and r = −0.592, P = 0.010, respectively).

    Conclusions

    A significant 3-year whole-brain atrophy was not reflected in mean metabolite change of non-lesional white matter. In addition, our results suggest that CSF levels of NFL and tau correlate with brain atrophy development and may be used for evaluating treatment response in inflammatory active MS.

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  • 87.
    Middleton, Michael
    et al.
    Department of Radiology, University of California, San Diego, CA, USA.
    Haufe, William
    Department of Radiology, University of California, San Diego, CA, USA.
    Hooker, Jonathan
    Department of Radiology, University of California, San Diego, CA, USA.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Tunón, Patrik
    Advanced MR Analytics AB, Linköping.
    Hamilton, Gavin
    Department of Radiology, University of California, San Diego, CA.
    Wolfson, Tanya
    Computational and Applied Statistics Laboratory (CASL), San Diego Supercomputing Center (SDSC), University of California, San Diego, CA.
    Gamst, Anthony
    Computational and Applied Statistics Laboratory (CASL), San Diego Supercomputing Center (SDSC), University of California, San Diego, CA.
    Loomba, Rohit
    3Department of Medicine (Division of Gastroenterology and Hepatology), University of California, San Diego, CA.
    Sirlin, Claude
    Department of Radiology, University of California, San Diego, CA.
    Quantifying Abdominal Adipose Tissue and Thigh Muscle Volume and Hepatic Proton Density Fat Fraction: Repeatability and Accuracy of an MR Imaging–based, Semiautomated Analysis Method2017In: Radiology, ISSN 0033-8419, E-ISSN 1527-1315, Vol. 283, no 2, p. 438-449Article in journal (Refereed)
    Abstract [en]

    Purpose

    The purpose of this study was to determine the repeatability and accuracy of an   commercially available (Advanced MR Analytics [AMRA®]; Linköping, Sweden) magnetic resonance imaging (MRI)-based, semi-automated method to quantify abdominal adipose tissue and thigh muscle volume as well as hepatic proton density fat fraction (PDFF)

    Materials and Methods

    This prospective study was approved by an institutional review board (IRB) and was Health Insurance Portability and Accountability Act (HIPAA) compliant. All subjects provided written informed consent. Inclusion criteria were age ≥ 18 years, and willingness to participate. Exclusion criteria were contraindication to MRI. Three-dimensional, T1-weighted, dual-echo body-coil images were acquired from base of skull to knees at 3T, twice before and once after taking subjects off the scanner table (total of three acquisitions). Source images were reconstructed offline to generate water, and calibrated fat images where pure adipose tissue has unit value and absence of adipose tissue has zero value. Abdominal adipose tissues and thigh muscles were segmented, and their volumes estimated using AMRA  a semi-automated analysis method and, as a reference standard, manually. Hepatic PDFF was estimated using a confounder-corrected chemical-shift encoded MRI method with hybrid complex-magnitude reconstruction., and, as a reference standard, with magnetic resonance spectroscopy (MRS). Tissue volume and hepatic PDFF intra- and inter-examination repeatability was assessed by intraclass correlation (ICC) and coefficient of variation (CV) analysis. Tissue volume and hepatic PDFF accuracies were assessed by linear regression using their respective reference standards.

    Results

    Twenty adult subjects were enrolled (18 female, age range 25 - 76 yrs, body mass index range 19.3 to 43.9 kg/m2). Adipose and thigh muscle tissue volumes estimated using the semi-automated analysis method had intra-and inter-examination ICCs between 0.996 and 0.998, and CVs between 1.5 and 3.6%. For hepatic MRI PDFF, intra- and inter-examination ICCs were ≥ 0.994 and CVs, ≤ 7.3%. Agreement between semi-automated and manual volume estimates, and between MRI and MRS hepatic PDFF estimates, was high, with regression slopes and intercepts not significantly different from the identity line (all p’s > 0.05), and R2’s between 0.744 and 0.994.

    Conclusions

    This MRI-based, semi-automated method provides high repeatability, and high accuracy for estimating abdominal adipose tissue and thigh muscle volumes, and hepatic PDFF.

  • 88.
    Middleton, Michael
    et al.
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Haufe, William
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Hooker, Jonathan
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Advanced MR Analytics AB, Linköping, Sweden.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Advanced MR Analytics AB, Linköping, Sweden.
    Romu, Thobias
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Advanced MR Analytics AB, Linköping, Sweden.
    Tunón, Patrik
    Advanced MR Analytics AB, Linköping, Sweden.
    Szeverenyi, Nick
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Hamilton, Gavin
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Wolfson, Tanya
    Department of Radiology, University of California, San Diego, San Diego, CA, United States; Computational and Applied Statistics Laboratory (CASL), University of California, San Diego, San Diego, CA, United States.
    Gamst, Anthony
    Department of Radiology, University of California, San Diego, San Diego, CA, United States; Computational and Applied Statistics Laboratory (CASL), University of California, San Diego, San Diego, CA, United States.
    Loomba, Rohit
    Department of Medicine, University of California, San Diego, San Diego, CA, United States.
    Sirlin, Claude B.
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Repeatability and accuracy of a novel, MRI-based, semi-automated analysis method for quantifying abdominal adipose tissue and thigh muscle volumes2016Conference paper (Other academic)
    Abstract [en]

    Current MRI methods to estimate body tissue compartment volumes rely on manual segmentation, which is laborious, expensive, not widely available outside specialized centers, and not standardized. To address these concerns, a novel, semi-automated image analysis method has been developed. Image acquisition takes about six minutes, and uses widely available MRI pulse sequences. We found that this method permits comprehensive body compartment analysis and provides high repeatability and accuracy. Current and future clinical and drug development studies may benefit from this methodology, as may clinical settings where monitoring change in these measures is desired.

  • 89.
    Mihon, Mirela
    et al.
    University of Politehn Bucuresti, Romania; Horia Hulubei National Institute Phys and Nucl Engn, Romania.
    Stelian Tuta, Catalin
    Horia Hulubei National Institute Phys and Nucl Engn, Romania.
    Catrinel Ion, Alina
    University of Politehn Bucuresti, Romania.
    Koziorowski, Jacek
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Niculae, Dana
    Horia Hulubei National Institute Phys and Nucl Engn, Romania.
    Lavric, Vasile
    University of Politehn Bucuresti, Romania.
    Draganescu, Doina
    Horia Hulubei National Institute Phys and Nucl Engn, Romania; Carol Davila University of Medical and Pharm, Romania.
    INFLUENCE OF THE SEPARATION PARAMETERS APPLIED FOR DETERMINATION OF IMPURITIES FDG AND CLDG2017In: Farmacia, ISSN 0014-8237, E-ISSN 2065-0019, Vol. 65, no 1, p. 153-158Article in journal (Refereed)
    Abstract [en]

    2-fluoro-2-deoxy-D-glucose (FDG) and 2-chloro-2-deoxy-D-glucose (CIDG) are chemical impurities found in the 2-[F-18]fluoro-2-deoxy-D-glucose products (F-18-FDG). The objective of this study was to find the best condition for the separation of FDG and CIDG, evaluating different columns under various operating conditions. Chromatographic parameters such as column temperature, composition and flow rate of the mobile phase were the independent variables used in the optimization process. The optimized method was validated and validation results showed a good accuracy, repeatability and reproducibility.

  • 90.
    Morales Drissi, Natasha
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    Landtblom, Anne-Marie
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Neurology. Linköping University, Center for Medical Image Science and Visualization (CMIV). Uppsala Univ, Sweden.
    Szakacs, Attila
    Univ Gothenburg, Sweden.
    Hallbook, Tove
    Univ Gothenburg, Sweden.
    Darin, Niklas
    Univ Gothenburg, Sweden.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV). AMRA Med AB, Linkoping, Sweden.
    Engström, Maria
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Unexpected Fat Distribution in Adolescents With Narcolepsy2018In: Frontiers in Endocrinology, ISSN 1664-2392, E-ISSN 1664-2392, Vol. 9, article id 728Article in journal (Refereed)
    Abstract [en]

    Narcolepsy type 1 is a chronic sleep disorder with significantly higher BMI reported in more than 50% of adolescent patients, putting them at a higher risk for metabolic syndrome in adulthood. Although well-documented, the body fat distribution and mechanisms behind weight gain in narcolepsy are still not fully understood but may be related to the loss of orexin associated with the disease. Orexin has been linked to the regulation of brown adipose tissue (BAT), a metabolically active fat involved in energy homeostasis. Previous studies have used BMI and waist circumference to characterize adipose tissue increases in narcolepsy but none have investigated its specific distribution. Here, we examine adipose tissue distribution in 19 adolescent patients with narcolepsy type 1 and compare them to 17 of their healthy peers using full body magnetic resonance imaging (MRI). In line with previous findings we saw that the narcolepsy patients had more overall fat than the healthy controls, but contrary to our expectations there were no group differences in supraclavicular BAT, suggesting that orexin may have no effect at all on BAT, at least under thermoneutral conditions. Also, in line with previous reports, we observed that patients had more total abdominal adipose tissue (TAAT), however, we found that they had a lower ratio between visceral adipose tissue (VAT) and TAAT indicating a relative increase of subcutaneous abdominal adipose tissue (ASAT). This relationship between VAT and ASAT has been associated with a lower risk for metabolic disease. We conclude that while weight gain in adolescents with narcolepsy matches that of central obesity, the lower VAT ratio may suggest a lower risk of developing metabolic disease.

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  • 91.
    Nasr, Patrik
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Forsgren, Mikael F.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Wolfram MathCore AB, Linköping, Sweden.
    Ignatova, Simone
    Linköping University, Department of Clinical and Experimental Medicine, Divison of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Clinical pathology.
    Dahlström, Nils
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Cedersund, Gunnar
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Norén, Bengt
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    Ekstedt, Mattias
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Using a 3% Proton Density Fat Fraction as a Cut-off Value Increases Sensitivity of Detection of Hepatic Steatosis, Based on Results from Histopathology Analysis2017In: Gastroenterology, ISSN 0016-5085, E-ISSN 1528-0012, Vol. 153, no 1, p. 53-+Article in journal (Refereed)
    Abstract [en]

    It is possible to estimate hepatic triglyceride content by calculating the proton density fat fraction (PDFF), using proton magnetic resonance spectroscopy (less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS), instead of collecting and analyzing liver biopsies to detect steatosis. However, the current PDFF cut-off value (5%) used to define steatosis by magnetic resonance was derived from studies that did not use histopathology as the reference standard. We performed a prospective study to determine the accuracy of less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF in measurement of steatosis using histopathology analysis as the standard. We collected clinical, serologic, less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF, and liver biopsy data from 94 adult patients with increased levels of liver enzymes (6 months or more) referred to the Department of Gastroenterology and Hepatology at Linköping University Hospital in Sweden from 2007 through 2014. Steatosis was graded using the conventional histopathology method and fat content was quantified in biopsy samples using stereological point counts (SPCs). We correlated less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF findings with SPCs (r = 0.92; P less than.001). less thansuperscriptgreater than1less than/superscriptgreater thanH-MRS PDFF results correlated with histopathology results (ρ = 0.87; P less than.001), and SPCs correlated with histopathology results (ρ = 0.88; P less than.001). All 25 subjects with PDFF values of 5.0% or more had steatosis based on histopathology findings (100% specificity for PDFF). However, of 69 subjects with PDFF values below 5.0% (negative result), 22 were determined to have steatosis based on histopathology findings (53% sensitivity for PDFF). Reducing the PDFF cut-off value to 3.0% identified patients with steatosis with 100% specificity and 79% sensitivity; a PDFF cut-off value of 2.0% identified patients with steatosis with 94% specificity and 87% sensitivity. These findings might be used to improve non-invasive detection of steatosis.

  • 92.
    Newman, David
    et al.
    Department of Radiology, Norfolk & Norwich University Hospital, UK.
    Kelly-Morland, Christian
    Department of Radiology, Norfolk & Norwich University Hospital, UK.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Kasmai, Bahman
    Department of Radiology, Norfolk & Norwich University Hospital, UK.
    Greenwood, Richard
    Department of Radiology, Norfolk & Norwich University Hospital, UK.
    Malcolm, Paul
    Department of Radiology, Norfolk & Norwich University Hospital, UK.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Toms, Andoni
    Department of Radiology, Norfolk & Norwich University Hospital, UK.
    Test–retest reliability of rapid whole body and compartmental fat volume quantification on a widebore 3T MR system in normal-weight, overweight, and obese subjects2016In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 44, no 6, p. 1464-1473Article in journal (Refereed)
    Abstract [en]

    Purpose

    To measure the test–retest reliability of rapid (<15 min) whole body and visceral fat volume quantification in normal and obese subjects on a widebore 3T MR system and compare it with conventional manual segmentation.

    Materials and Methods

    Thirty participants (body mass index [BMI] 20.1–48.6 kg/m2) underwent two whole-body magnetic resonance imaging (MRI) examinations on a widebore 3T machine using a 2-point Dixon technique. Phase sensitive reconstruction and intensity inhomogeneity correction produced quantitative datasets of total adipose tissue (TAT), abdominal subcutaneous adipose tissue (ASAT), and visceral adipose tissue (VAT). The quantification was performed automatically using nonrigid atlas-based segmentation and compared with manual segmentation (SliceOmatic).

    Results

    The mean TAT was 31.74 L with a coefficient of variation (CV) of 0.79% and a coefficient of repeatability (CR) of 0.49 L. The ASAT was 7.92 L with a CV of 2.98% and a CR of 0.46 L. There was no significant difference in the semiautomated and manually segmented VAT (P = 0.73) but there were differences in the reliability of the two techniques. The mean semiautomated VAT was 2.56 L, CV 1.8%, and CR 0.09 L compared to the mean manually segmented VAT of 3.12 L, where the CV was 6.3% and the CR was 0.39 L.

    Conclusion

    Rapid semiautomated whole body and compartmental fat volume quantification can be derived from a widebore 3T system, for a range of body sizes including obese patients, with “almost perfect” test–retest reliability.

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  • 93.
    Nilsson Althén, Jonas
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Sandborg, Michael
    Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Medicine and Health Sciences.
    VERIFICATION OF INDICATED SKIN ENTRANCE AIR KERMA FORCARDIAC X-RAY-GUIDED INTERVENTION USING GAFCHROMIC FILM2016In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 169, no 1-4, p. 245-248Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to verify the indicated maximum entrance surface air kerma (ESAK) using a GE Innova IGS 520 imaging system during cardiac interventional procedures. Gafchromic XR RV3 films were used for the patient measurements to monitor the maximum ESAK. The films were scanned and calibrated to measure maximum ESAK. Thermoluminescent dosemeters were used to measure the backscatter factor from an anthropomorphic thorax phantom. The measured backscatter factor, 1.53, was in good agreement with Monte Carlo simulations but higher than the one used by the imaging system, 1.20. The median of the ratio between indicated maximum ESAK and measured maximum ESAKwas 0.68. In this work, the indicated maximum ESAK by the imaging system’s dose map model underestimates the measured maximum ESAK by 32 %. The threshold ESAK for follow-up procedures for patient with skin dose in excess of 2 Gy will be reduced to 1.4 Gy.

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  • 94.
    Norberg, Pernilla
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Olsson, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Alm Carlsson, Gudrun
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Sandborg, Michael
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Gustafsson, Agneta
    Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Optimisation of quantitative lung SPECT applied to mild COPD: a software phantom simulation study2015In: EJNMMI research, ISSN 2191-219X, Vol. 5, no 16Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The amount of inhomogeneities in a (99m)Tc Technegas single-photon emission computed tomography (SPECT) lung image, caused by reduced ventilation in lung regions affected by chronic obstructive pulmonary disease (COPD), is correlated to disease advancement. A quantitative analysis method, the CVT method, measuring these inhomogeneities was proposed in earlier work. To detect mild COPD, which is a difficult task, optimised parameter values are needed.

    METHODS: In this work, the CVT method was optimised with respect to the parameter values of acquisition, reconstruction and analysis. The ordered subset expectation maximisation (OSEM) algorithm was used for reconstructing the lung SPECT images. As a first step towards clinical application of the CVT method in detecting mild COPD, this study was based on simulated SPECT images of an advanced anthropomorphic lung software phantom including respiratory and cardiac motion, where the mild COPD lung had an overall ventilation reduction of 5%.

    RESULTS: The best separation between healthy and mild COPD lung images as determined using the CVT measure of ventilation inhomogeneity and 125 MBq (99m)Tc was obtained using a low-energy high-resolution collimator (LEHR) and a power 6 Butterworth post-filter with a cutoff frequency of 0.6 to 0.7 cm(-1). Sixty-four reconstruction updates and a small kernel size should be used when the whole lung is analysed, and for the reduced lung a greater number of updates and a larger kernel size are needed.

    CONCLUSIONS: A LEHR collimator and 125 (99m)Tc MBq together with an optimal combination of cutoff frequency, number of updates and kernel size, gave the best result. Suboptimal selections of either cutoff frequency, number of updates and kernel size will reduce the imaging system's ability to detect mild COPD in the lung phantom.

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  • 95.
    Norén, Bengt
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Dahlström, Nils
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Forsgren, Mikael
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Kechagias, Stergios
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Almer, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Gastroentorology.
    Wirell, Staffan
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Smedby, Örjan
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Radiology in Linköping.
    Lundberg, Peter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics.
    Visual assessment of biliary excretion of Gd-EOB-DTPA in patients with suspected diffuse liver disease – a biopsy-controlled prospective study2015In: European Journal of Radiology Open, ISSN 2352-0477, Vol. 2, p. 19-25Article in journal (Refereed)
    Abstract [en]

    Objectives: To qualitatively evaluate late dynamic contrast phases, 10, 20 and 30 min, after administration of Gd-EOB-DTPA with regard to biliary excretion in patients presenting with elevated liver enzymes without any clinical signs of cirrhosis or hepatic decompensation and to compare the visual assessment of contrast agent excretion with histo-pathological fibrosis stage, contrast uptake parameters and blood tests.

    Methods: 29 patients were prospectively examined using 1.5-T MRI. The visually assessed presence (1) or absence (0) of contrast agent for each of five anatomical regions in randomly reviewed time-series was summarised on a four grade scale. The scores, including a total visual score, were related to the histo-pathological findings, the quantitative contrast agent uptake parameters and blood tests

    Results: No relationship between the fibrosis grade or contrast uptake parameters expressed as KHep or LSC_N could be established. A negative correlation between the visual assessment and ALP was found. Comparing a sub-group of cholestatic patients with fibrosis score and Gd-EOB-DTPAdynamic parameters did not add any additional significant correlation.

    Conclusions: In this prospective study with a limited number of patients we were not able to demonstrate a correlation between visually assessed biliary excretion of Gd-EOB-DTPA and  histo-pathological or contrast uptake parameters.

  • 96.
    Paiva Fonseca, Gabriel
    et al.
    IPEN CNEN SP, Brazil; Maastricht University, Netherlands.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Karolinska University Hospital, Sweden.
    Reniers, Brigitte
    Maastricht University, Netherlands; Hasselt University, Belgium.
    Nilsson, Josef
    Karolinska University Hospital, Sweden.
    Persson, Maria
    Karolinska University Hospital, Sweden.
    Yoriyaz, Helio
    IPEN CNEN SP, Brazil.
    Verhaegen, Frank
    Maastricht University, Netherlands; McGill University, Canada.
    Dose specification for Ir-192 high dose rate brachytherapy in terms of dose-to-water-in-medium and dose-to-medium-in-medium2015In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 60, no 11, p. 4565-4579Article in journal (Refereed)
    Abstract [en]

    Dose calculation in high dose rate brachytherapy with Ir-192 is usually based on the TG-43U1 protocol where all media are considered to be water. Several dose calculation algorithms have been developed that are capable of handling heterogeneities with two possibilities to report dose: dose-to-medium-inmedium (D-m,D-m) and dose-to-water-in-medium (D-w,D-m). The relation between D-m,D-m and D-w,D-m for Ir-192 is the main goal of this study, in particular the dependence of D-w,D-m on the dose calculation approach using either large cavity theory (LCT) or small cavity theory (SCT). A head and neck case was selected due to the presence of media with a large range of atomic numbers relevant to tissues and mass densities such as air, soft tissues and bone interfaces. This case was simulated using a Monte Carlo (MC) code to score: D-m,D-m, D-w,D-m (LCT), mean photon energy and photon fluence. D-w,D-m (SCT) was derived from MC simulations using the ratio between the unrestricted collisional stopping power of the actual medium and water. Differences between D-m,D-m and D-w,D-m (SCT or LCT) can be negligible (less than1%) for some tissues e.g. muscle and significant for other tissues with differences of up to 14% for bone. Using SCT or LCT approaches leads to differences between D-w,D-m (SCT) and D-w,D-m (LCT) up to 29% for bone and 36% for teeth. The mean photon energy distribution ranges from 222 keV up to 356 keV. However, results obtained using mean photon energies are not equivalent to the ones obtained using the full, local photon spectrum. This work concludes that it is essential that brachytherapy studies clearly report the dose quantity. It further shows that while differences between D-m,D-m and D-w,D-m (SCT) mainly depend on tissue type, differences between D-m,D-m and D-w,D-m (LCT) are, in addition, significantly dependent on the local photon energy fluence spectrum which varies with distance to implanted sources.

  • 97.
    Persson, Maria
    et al.
    Karolinska Univ Hosp, Sweden.
    Nilsson, Josef
    Karolinska Univ Hosp, Sweden.
    Carlsson Tedgren, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Karolinska Univ Hosp, Sweden.
    Experience of using MOSFET detectors for dose verification measurements in an end-to-end Ir-192 brachytherapy quality assurance system2018In: Brachytherapy, ISSN 1538-4721, E-ISSN 1873-1449, Vol. 17, no 1, p. 227-233Article in journal (Refereed)
    Abstract [en]

    PURPOSE: Establishment of an end-to-end system for the brachytherapy (BT) dosimetric chain could be valuable in clinical quality assurance. Here, the development of such a system using MOSFET (metal oxide semiconductor field effect transistor) detectors and experience gained during 2 years of use are reported with focus on the performance of the MOSFET detectors. METHODS AND MATERIALS: A bolus phantom was constructed with two implants, mimicking prostate and head amp; neck treatments, using steel needles and plastic catheters to guide the Ir-192 source and house the MOSFET detectors. The phantom was taken through the BT treatment chain from image acquisition to dose evaluation. During the 2-year evaluation-period, delivered doses were verified a total of 56 times using MOSFET detectors which had been calibrated in an external Co-60 beam. An initial experimental investigation on beam quality differences between Ir-192 and Co-60 is reported. RESULTS: The standard deviation in repeated MOSFET measurements was below 3% in the six measurement points with dose levels above 2 Gy. MOSFET measurements overestimated treatment planning system doses by 2-7%. Distance-dependent experimental beam quality correction factors derived in a phantom of similar size as that used for end-to-end tests applied on a time-resolved measurement improved the agreement. CONCLUSIONS: MOSFET detectors provide values stable over time and function well for use as detectors for end-to-end quality assurance purposes in 192Ir BT. Beam quality correction factors should address not only distance from source but also phantom dimensions. (C) 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  • 98.
    Peterson, Pernilla
    et al.
    Skåne University Hospital, Sweden.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Brorson, Hakan
    Lund University, Sweden.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Mansson, Sven
    Skåne University Hospital, Sweden.
    Fat Quantification in Skeletal Muscle Using Multigradient-Echo Imaging: Comparison of Fat and Water References2016In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 43, no 1, p. 203-212Article in journal (Refereed)
    Abstract [en]

    Purpose: To investigate the precision, accuracy, and repeatability of water/fat imaging-based fat quantification in muscle tissue using a large flip angle (FA) and a fat reference for the calculation of the proton density fat fraction (FF). Comparison is made to a small FA water reference approach. Materials and Methods: An Intralipid phantom and both forearms of six patients suffering from lymphedema and 10 healthy volunteers were investigated at 1.5T. Two multigradient-echo sequences with eight echo times and FAs of 10 degrees and 85 degrees were acquired. For healthy volunteers, the acquisition of the right arm was performed twice with repositioning. From each set, water reference FF and fat reference FF images were reconstructed and the average FF and the standard deviation were calculated within the subfascial compartment. The small FA water reference was considered the reference standard. Results: A high agreement was found between the small FA water reference and large FA fat reference methods (FF bias=0.31%). In this study, the large FA fat reference approach also resulted in higher precision (38% smaller FF standard deviation in homogenous muscle tissue), but no significant difference in repeatability between the various methods was detected (coefficient of repeatability of small FA water reference approach 0.41%). Conclusion: The precision of fat quantification in muscle tissue can be increased with maintained accuracy using a larger flip angle, if a fat reference instead of a water reference is used.

  • 99.
    Petridou, Elia
    et al.
    Department of Radiology, Norfolk and Norwich University hospitals, Norwich, Norfolk, United Kingdom.
    Kibiro, Minnie
    Department of Radiology, Norfolk and Norwich University hospitals, Norwich, Norfolk, United Kingdom.
    Gladwell, Christina
    Department of Radiology, Norfolk and Norwich University hospitals, Norwich, Norfolk, United Kingdom.
    Malcolm, Paul
    Department of Radiology, Norfolk and Norwich University hospitals, Norwich, Norfolk, United Kingdom.
    Juette, Arne
    Department of Radiology, Norfolk and Norwich University hospitals, Norwich, Norfolk, United Kingdom.
    Toms, Andoni
    Department of Radiology, Norfolk and Norwich University hospitals, Norwich, Norfolk, United Kingdom.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Advanced MR Analytics AB, Linköping, Sweden.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Advanced MR Analytics AB, Linköping, Sweden.
    Denton, Erika
    Department of Radiology, Norfolk and Norwich University hospitals, Norwich, Norfolk, United Kingdom.
    Breast fat volume measurement in a wide-bore 3T MR: comparison of traditional mammographic density evaluation with MR density measurements using automatic segmentation.2015Conference paper (Other academic)
    Abstract [en]

    Aims and objectives

    Variations in breast density in imaging are caused by varying proportions of fat and fibro-glandular tissue. Breast density is an independent marker of breast cancer risk and therefore a number of techniques have been developed to measure breast density using different imaging modalities. The aim of this research was to compare a fully automated technique of producing volumetric measurements of fat and fibroglandular breast tissue from segmented magnetic resonance imaging (MRI) and to compare with the well-established, observer-dependent Breast Imaging Reporting and Data Systems (BI-RADS) density classification using mammography.

    Methods and materials

    This was a prospective inter-method comparison study. The study design was a prospective analysis of volumetric breast density obtained from breast MRI scans compared with mammographic breast density using BIRADS. Ethical approval for the study was obtained from the local Research Ethics Committee. 40 women undergoing mammography and dynamic breast MRI as part of their clinical management were recruited. Fat-water separated MR images derived from a 2 point Dixon technique using phase-sensitive reconstruction and atlas based segmentation were obtained before and after the administration of intravenous gadolinium. Breast density, which was defined the proportion of breast fat subtracted from the total volume of the breast, was assessed using proprietary software (Advanced MR Analytics (AMRA), Linköping, Sweden). The method was previously described and first used for measurement of abdominal fat.

    The results were compared to the widely used four-quartile quantitative BIRADS scale undertaken by two experienced breast radiologists. 

    Results

    The mean unenhanced breast percentage of fibro-glandular tissue measured on MRI was 0.31 ± 0.22 (mean ± SD) for the left and 0.29 ± 0.21 for the right. The mean density on the contrast-enhanced images was 0.32 ± 0.19 for the left and 0.32 ± 0.2 for right. There was "almost perfect" correlation between the quantification pre and post-contrast breast fibro- glandular tissue quantification: Spearman correlation rho=0.98 (95% confidence intervals (CI): 0.97-0.99) for the left and rho=0.99 (CI: 0.98-0.99) for the right.

    For each of the BIRADS scores 1-4 observer 1 scored a total number of breasts as n=2,35,26,15 (total 80) and observer 2 scored n=4,25,45,16 respectively. Correlation between BIRADS scores and automated MRI breast density was significant for both operators, Spearman Correlation coefficient rho=0.75. 

    Conclusion

    Automated breast fat density measurement using MR correlates strongly with the current mammographic standard BIRADS. Results for percentage fibro-glandular component on unenhanced breast MR correlate very closely with post-contrast MR. Breast density measurements derived from automated segmentation of unenhanced breast MRI could be used instead of mammographic measurements for assessing breast cancer risk. 

  • 100.
    Petridou, Elia
    et al.
    Norfolk and Norwich University Hospital, UK.
    Kibiro, Minnie
    Norfolk and Norwich University Hospital, UK.
    Gladwell, Christina
    Norfolk and Norwich University Hospital, UK.
    Malcolm, Paul
    Norfolk and Norwich University Hospital, UK.
    Toms, Andoni
    Norfolk and Norwich University Hospital, UK.
    Juette, Arne
    Norfolk and Norwich University Hospital, UK.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering.
    Dahlqvist Leinhard, Olof
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Linköping University, Faculty of Medicine and Health Sciences.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Science & Engineering.
    Kasmai, Bahman
    Norfolk and Norwich University Hospital, UK.
    Denton, Erika
    Norfolk and Norwich University Hospital, UK.
    Breast fat volume measurement in a wide-bore 3T MR: comparison of traditional mammographic density evaluation with MR density measurements using automatic segmentation.2017In: Clinical Radiology, ISSN 0009-9260, E-ISSN 1365-229X, Vol. 72, no 7, p. 565-572Article in journal (Refereed)
    Abstract [en]

    Aim

    To compare magnetic resonance imaging (MRI) derived breast density measurements using automatic segmentation algorithms with radiologist estimations using the Breast Imaging Reporting and Data Systems (BI-RADS) density classification.

    Materials and Methods

    40 women undergoing mammography and dynamic breast MRI as part of their clinical management were recruited. Fat-water separated MR images derived from a 2-point Dixon technique, phase sensitive reconstruction and atlas based segmentation were obtained before and after intravenous contrast. Breast density was assessed using software from Advanced MR Analytics (AMRA), Linköping, Sweden with results compared to the widely used four-quartile quantitative BIRADS scale.

    Results

    The proportion of glandular tissue of the breast on MRI was derived from the AMRA sequence. The mean unenhanced breast density was 0.31 ± 0.22 (mean ± SD) (left) 

    and 0.29 ± 0.21 (right). Mean breast density on post-contrast images was 0.32 ± 0.19 (left) and 0.32 ± 0.2 (right). There was "almost perfect" correlation between pre and post-contrast breast density quantification: Spearman correlation rho=0.98 (95% confidence intervals (CI): 0.97-0.99) (left) and rho=0.99(CI: 0.98-0.99) (right). The 95% limits of agreement were -0.11-0.08 (left) and -0.08-0.03 (right).

    Interobserver reliability for BIRADS is "substantial": weighted Kappa k=0.8 (CI: 0.74- 0.87). The Spearman Correlation coefficient between BIRADs and MR breast density was rho=0.73 (CI: 0.60-0.82) (left) and rho=0.75 (CI: 0.63-0.83) (right) which is also "substantial".

    Conclusion

    The AMRA sequence provides a fully automated, reproducible, objective assessment of fibroglandular breast tissue proportion that correlates well with mammographic assessment of breast density with the added advantage of avoidance of ionising radiation. 

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