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  • 251.
    Gu, Xuan
    et al.
    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).
    Eklund, Anders
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Özarslan, Evren
    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).
    Knutsson, Hans
    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).
    Using the wild bootstrap to quantify uncertainty in mean apparent propagator MRI2019In: Frontiers in Neuroinformatics, ISSN 1662-5196, E-ISSN 1662-5196, Vol. 13, article id 43Article in journal (Refereed)
    Abstract [en]

    Purpose: Estimation of uncertainty of MAP-MRI metricsis an important topic, for several reasons. Bootstrap deriveduncertainty, such as the standard deviation, providesvaluable information, and can be incorporated in MAP-MRIstudies to provide more extensive insight.

    Methods: In this paper, the uncertainty of different MAPMRImetrics was quantified by estimating the empirical distributionsusing the wild bootstrap. We applied the wildbootstrap to both phantom data and human brain data, andobtain empirical distributions for theMAP-MRImetrics returnto-origin probability (RTOP), non-Gaussianity (NG) and propagatoranisotropy (PA).

    Results: We demonstrated the impact of diffusion acquisitionscheme (number of shells and number of measurementsper shell) on the uncertainty of MAP-MRI metrics.We demonstrated how the uncertainty of these metrics canbe used to improve group analyses, and to compare differentpreprocessing pipelines. We demonstrated that withuncertainty considered, the results for a group analysis canbe different.

    Conclusion: Bootstrap derived uncertain measures provideadditional information to the MAP-MRI derived metrics, andshould be incorporated in ongoing and future MAP-MRIstudies to provide more extensive insight.

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  • 252.
    Gu, Xuan
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Knutsson, Hans
    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).
    Nilsson, Markus
    Department of Clinical Sciences, Radiology, Lund UniversityLundSweden.
    Eklund, Anders
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Generating Diffusion MRI Scalar Maps from T1 Weighted Images Using Generative Adversarial Networks2019In: Image Analysis: Lecture Notes in Computer Science / [ed] Felsberg M., Forssén PE., Sintorn IM., Unger J., Springer Publishing Company, 2019, p. 489-498Conference paper (Refereed)
    Abstract [en]

    Diffusion magnetic resonance imaging (diffusion MRI) is a non-invasive microstructure assessment technique. Scalar measures, such as FA (fractional anisotropy) and MD (mean diffusivity), quantifying micro-structural tissue properties can be obtained using diffusion models and data processing pipelines. However, it is costly and time consuming to collect high quality diffusion data. Here, we therefore demonstrate how Generative Adversarial Networks (GANs) can be used to generate synthetic diffusion scalar measures from structural T1-weighted images in a single optimized step. Specifically, we train the popular CycleGAN model to learn to map a T1 image to FA or MD, and vice versa. As an application, we show that synthetic FA images can be used as a target for non-linear registration, to correct for geometric distortions common in diffusion MRI.

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  • 253.
    Gu, Xuan
    et al.
    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).
    Sidén, Per
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering.
    Wegmann, Bertil
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering.
    Eklund, Anders
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Villani, Mattias
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering.
    Knutsson, Hans
    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).
    Bayesian Diffusion Tensor Estimation with Spatial Priors2017In: CAIP 2017: Computer Analysis of Images and Patterns, 2017, Vol. 10424, p. 372-383Conference paper (Refereed)
    Abstract [en]

    Spatial regularization is a technique that exploits the dependence between nearby regions to locally pool data, with the effect of reducing noise and implicitly smoothing the data. Most of the currently proposed methods are focused on minimizing a cost function, during which the regularization parameter must be tuned in order to find the optimal solution. We propose a fast Markov chain Monte Carlo (MCMC) method for diffusion tensor estimation, for both 2D and 3D priors data. The regularization parameter is jointly with the tensor using MCMC. We compare FA (fractional anisotropy) maps for various b-values using three diffusion tensor estimation methods: least-squares and MCMC with and without spatial priors. Coefficient of variation (CV) is calculated to measure the uncertainty of the FA maps calculated from the MCMC samples, and our results show that the MCMC algorithm with spatial priors provides a denoising effect and reduces the uncertainty of the MCMC samples.

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  • 254.
    Gupta, Vikas
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bustamante, Mariana
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Fredriksson, Alexandru
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Carlhäll, Carljohan
    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 Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ebbers, Tino
    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 Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Improving left ventricular segmentation in four-dimensional flow MRI using intramodality image registration for cardiac blood flow analysis2018In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 79, no 1, p. 554-560Article in journal (Refereed)
    Abstract [en]

    PurposeAssessment of blood flow in the left ventricle using four-dimensional flow MRI requires accurate left ventricle segmentation that is often hampered by the low contrast between blood and the myocardium. The purpose of this work is to improve left-ventricular segmentation in four-dimensional flow MRI for reliable blood flow analysis. MethodThe left ventricle segmentations are first obtained using morphological cine-MRI with better in-plane resolution and contrast, and then aligned to four-dimensional flow MRI data. This alignment is, however, not trivial due to inter-slice misalignment errors caused by patient motion and respiratory drift during breath-hold based cine-MRI acquisition. A robust image registration based framework is proposed to mitigate such errors automatically. Data from 20 subjects, including healthy volunteers and patients, was used to evaluate its geometric accuracy and impact on blood flow analysis. ResultsHigh spatial correspondence was observed between manually and automatically aligned segmentations, and the improvements in alignment compared to uncorrected segmentations were significant (Pamp;lt;0.01). Blood flow analysis from manual and automatically corrected segmentations did not differ significantly (Pamp;gt;0.05). ConclusionOur results demonstrate the efficacy of the proposed approach in improving left-ventricular segmentation in four-dimensional flow MRI, and its potential for reliable blood flow analysis. Magn Reson Med 79:554-560, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.

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  • 255.
    Gupta, Vikas
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Lantz, Jonas
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Henriksson, Lilian
    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 Diagnostics, Department of Radiology in Linköping.
    Engvall, Jan
    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 Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Persson, 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 Diagnostics, Department of Radiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ebbers, Tino
    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 Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration2018In: Journal of Cardiovascular Computed Tomography, ISSN 1934-5925, Vol. 12, no 2, p. 139-148Article in journal (Refereed)
    Abstract [en]

    Background Assessment of myocardial deformation from time-resolved cardiac computed tomography (4D CT) would augment the already available functional information from such an examination without incurring any additional costs. A deformable image registration (DIR) based approach is proposed to allow fast and automatic myocardial tracking in clinical 4D CT images.

    Methods Left ventricular myocardial tissue displacement through a cardiac cycle was tracked using a B-spline transformation based DIR. Gradient of such displacements allowed Lagrangian strain estimation with respect to end-diastole in clinical 4D CT data from ten subjects with suspected coronary artery disease. Dice similarity coefficient (DSC), point-to-curve error (PTC), and tracking error were used to assess the tracking accuracy. Wilcoxon signed rank test provided significance of tracking errors. Topology preservation was verified using Jacobian of the deformation. Reliability of estimated strains and torsion (normalized twist angle) was tested in subjects with normal function by comparing them with normal strain in the literature.

    Results Comparison with manual tracking showed high accuracy (DSC: 0.99± 0.05; PTC: 0.56mm± 0.47 mm) and resulted in determinant(Jacobian) > 0 for all subjects, indicating preservation of topology. Average radial (0.13 mm), angular (0.64) and longitudinal (0.10 mm) tracking errors for the entire cohort were not significant (p > 0.9). For patients with normal function, average strain [circumferential, radial, longitudinal] and peak torsion estimates were: [-23.5%, 31.1%, −17.2%] and 7.22°, respectively. These estimates were in conformity with the reported normal ranges in the existing literature.

    Conclusions Accurate wall deformation tracking and subsequent strain estimation are feasible with the proposed method using only routine time-resolved 3D cardiac CT.

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  • 256.
    Gustafsson, Agnetha
    et al.
    University of Göteborg, Sahlgrenska University Hospital.
    Bake, Björn
    University of Göteborg, Sahlgrenska University Hospital.
    Jacobsson, Lars
    University of Göteborg, Sahlgrenska University Hospital.
    Johansson, Åke
    University of Göteborg, Sahlgrenska University Hospital.
    Ljungberg, Michael
    University of Lund.
    Moonen, Michaela
    University of Göteborg, Sahlgrenska University Hospital.
    Attenueringseffekter vid SPECT av lungor1995Conference paper (Refereed)
  • 257.
    Gustafsson, Agnetha
    et al.
    Department of Radiation Physics, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Bake, Björn
    Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Jacobsson, Lars
    Department of Radiation Physics, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Johansson, Åke
    Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Ljungberg, Michael
    Radiation Physics Department, University of Lund, Sweden .
    Moonen, Michaela
    Department of Clinical Physiology, University of Göteborg, Sahlgrenska University Hospital, Göteborg, Sweden .
    Evaluation of attenuation corrections using Monte Carlo simulated lung SPECT1998In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 43, no 8, p. 2325-2336Article in journal (Refereed)
    Abstract [en]

    SPECT (single photon emission computed tomography) images are distorted by photon attenuation. The effect is complex in the thoracic region due to different tissue densities. This study compares the effect on the image homogeneity of two different methods of attenuation correction in lung SPECT; one pre-processing and one post-processing method. This study also investigates the impact of attenuation correction parameters such as lung contour, body contour, density of the lung tissue and effective attenuation coefficient. The Monte Carlo technique was used to simulate SPECT studies of a digital thorax phantom containing a homogeneous activity distribution in the lung. Homogeneity in reconstructed images was calculated as the coefficient of variation (CV). The isolated effect of the attenuation correction was assessed by normalizing pixel values from the attenuation corrected lung by pixel values from the lung with no attenuation effects. Results show that the CV decreased from 12.8% with no attenuation correction to 4.4% using the post-processing method and true densities in the thoracic region. The impact of variations in the definition of the body contour was found to be marginal while the corresponding effect of variations in the lung contour was substantial.

  • 258.
    Gustafsson, Agnetha
    et al.
    Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Brundin, Helene
    Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Zachrisson, Helene
    Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Kvantifiering av DATscan  -  Jämförelse mellan filtrerad bakåtprojektion  och iterativ rekonstruktion.2008Conference paper (Other academic)
  • 259.
    Gustafsson, Agnetha
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Enander, Annika
    Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Evaluation of the reconstruction algorithms for two different matrix sizes: OSEM and Evolution Cardiac for myocardial SPECT.2010Conference paper (Refereed)
  • 260.
    Gustafsson, Agnetha
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Enander, Annika
    Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Utvärdering av OSEM och Evolution for Cardiac med två olika matrisstorlekar; för myokardscintigrafi med SPECT.2010Conference paper (Other academic)
  • 261.
    Gustafsson, Agnetha
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Grétarsdóttir, Jakobina
    Sahlgrenska Universitetssjukhuset, Göteborg.
    Which collimator should be used for myocardial perfusion SPECT, HR or GP?2006Conference paper (Other academic)
  • 262.
    Gustafsson, Agnetha
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Jacobsson, Lars
    University of Göteborg, Sahlgrenska University Hospital.
    Johansson, Åke
    University of Göteborg, Sahlgrenska University Hospital.
    Moonen, Michaela
    University of Göteborg, Sahlgrenska University Hospital.
    Tylén, Ulf
    University of Göteborg.
    Bake, Björn
    University of Göteborg, Sahlgrenska University Hospital.
    Attenueringseffekter vid lung-SPECT av friska försökspersoner1999Conference paper (Other academic)
  • 263.
    Gustafsson, Agnetha
    et al.
    Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Karlsson, Henrik
    Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Lindblom, Gunnar
    Östergötlands Läns Landsting, Centre for Diagnostics, Department of Radiology in Linköping.
    Dosering vid helkroppscan av skelettskintigrafi2006Conference paper (Other academic)
  • 264.
    Gustafsson, Agnetha
    et al.
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics UHL.
    Ärlig, Åsa
    Göteborg University, Sahlgrenska University Hospital.
    Jacobsson, Lars
    Göteborg University, Sahlgrenska University Hospital.
    Ljungberg, Michael
    Lund University.
    Wikkelsö, Carsten
    Göteborg University, Sahlgrenska University Hospital.
    Comptonbaserad spridningskorrektion och energifönsterinställning vid CBF SPECT: En Monte Carlo studie2000Conference paper (Other academic)
  • 265.
    Gustafsson, Agnetha
    et al.
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Ärlig, Åsa
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Jacobsson, Lars
    Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Ljungberg, Michael
    Radiation Physics Department, Lund University, The Jubileum Institute, Lund, Sweden .
    Wikkelsö, Carsten
    Institute of Clinical Neuroscience, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden .
    Dual-window scatter correction and energy window setting in cerebral blood flow SPECT: a Monte Carlo study2000In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 45, no 11, p. 3431-3440Article in journal (Refereed)
    Abstract [en]

    The image quality in SPECT studies of the regional cerebral blood flow (rCBF) performed with 99mTc-HMPAO is degraded by scattered photons. The finite energy resolution of the gamma camera makes the detection of scattered photons unavoidable, and this is observed in the image as an impaired contrast between grey and white matter structures.

    In this work, a Monte Carlo simulated SPECT study of a realistic voxel-based brain phantom was used to evaluate the resulting contrast-to-noise ratio for a number of energy window settings, with and without the dual-window scatter correction. Values of the scaling factor k, used to obtain the fraction of scattered photons in the photopeak window, were estimated for each energy window.

    The use of a narrower, asymmetric, energy discrimination window improved the contrast, with a subsequent increase in statistical noise due to the lower number of counts. The photopeak-window setting giving the best contrast-to-noise ratio was found to be the same whether or not scatter correction was applied. Its value was 17% centred at 142 keV. At the optimum photopeak-window setting, the contrast was improved by using scatter correction, but the contrast-to-noise ratio was made worse.

  • 266.
    Gustafsson, Filippa
    Linköping University, Department of Biomedical Engineering.
    Visualization and Quantification of Helical Flow in the Aorta using 4D Flow MRI2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Due to the complex anatomy of the heart, heart valves and aorta, blood flow in the aorta is known to be complex and can exhibit a swirling, or helical, flow pattern. The purpose of this thesis is to implement methods to quantify and visualize both the speed of helicity, referred to as the helicity density, and the direction of helicity, which is measured by the localized normalized helicity. Furthermore, the relationship between helicity and geometrical aorta parameters were studied in young and old healthy volunteers. Helicity and geometrical parameters were quantified for 22 healthy volunteers (12 old, 10 young) that were examined using 4D Flow MRI. The relation between helicity and the geometry of the aorta was explored, and the results showed that the tortuosity and the diameter of the aorta are related to the helicity, but the jet angle and flow displacement do not appear to play an important role. This suggests that in healthy volunteers the helical flow is primarily affected by the geometry of the aorta, although further trials should be performed to fully characterize the effects of aortic geometry. The results also show that the helicity changes with age between the two age groups and some of the geometrical parameters also has a significant difference between the age groups.

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  • 267. Gustavsson, U.
    et al.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Nilsson, Gert
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Lewis, D.H.
    Vasomotion in rat skeletal muscle induced by hemorrhage as recorded by laser Doppler flowmetry1991In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, no 42, p. 224-228Article in journal (Refereed)
  • 268.
    Gårdhagen, Roland
    et al.
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Renner, Johan
    Linköping University, Department of Mechanical Engineering. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Karlsson, Matts
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Assessment of Geometrical Influence on WSS Estimation in the Human Aorta2006In: WSEAS Transactions on Fluid Mechanics, ISSN 1790-5087, Vol. 4, no 1, p. 318-326Article in journal (Refereed)
    Abstract [en]

    Computational fluid dynamics simulations were performed on a stenosed human aorta with poststenotic dilatation, in order to estimate wall shear stress (WSS). WSS is important due to its correlation with atherosclerosis. Both steady-state and non-stationary simulations were conducted. Three different models were created from a set of MRI images. Comparison of geometrically different models was accomplished by using geometrical landmarks and a comparison parameter. Geometrical differences had larger influence on WSS magnitude than inflow rotation in steady-state results for the models used. In non-stationary flow the largest differences in WSS are found when the flow velocity near the wall is low e.g. when the inflow is low or in recirculation regions.

  • 269.
    Göransson, Nathanael
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Johansson, Johannes
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Alonso, Fabiola
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Postoperative lead movement after deep brain stimulation surgery and changes of stimulation area2017Conference paper (Other academic)
    Abstract [en]

    Introduction

    Lead movement after deep brain stimulation (DBS) may occur and influence the area of stimulation. The cause of the displacement is not fully understood. The aim of the study was to investigate differences in lead position between the day after surgery and approximately one month postoperatively and also simulate the electric field (EF) around the active contacts.

    Methods

    23 patients with movement disorders underwent DBS surgery (37 leads). CT at the two time points were co-fused respectively with the stereotactic images in Surgiplan. The coordinates (x, y, z) of the lead tips were compared between the two dates (paired t-test). 8 of these patients were selected for the EF simulation in Comsol Multiphysics.

    Results

    There was a significant discrepancy (mean ± s.d.) on the left lead: x (0.44 ± 0.72, p < 0.01), y (0.64 ± 0.54, p < 0.001), z (0.62 ± 0.71, p < 0.001).  On the right lead, corresponding values were: x (-0.11 ± 0.61, n.s.), y (0.71 ± 0.54, p < 0.001), z (0.49 ± 0.81, p < 0.05).  No correlation was found between bilateral (n =14) vs. unilateral DBS, gender (n = 17 male) and age < 60 years (n = 8).  The lead movement affected the EF spread (Fig. 1).

    Conclusion

    The left lead tip displayed a tendency to move lateral, anterior and inferior and the right a tendency to move anterior and inferior. Lead movement after DBS can be a factor to consider before starting the stimulation. The differences in the area of stimulation might affect clinical outcome.

  • 270.
    Gürlüler, Merve
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Quantitative Tissue Classification via Dual Energy Computed Tomography for Brachytherapy Treatment Planning: Accuracy of the Three Material Decomposition Method2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Dual Energy Computed Tomography (DECT) is an emerging technique that offers new possibilities to determine composition of tissues in clinical applications. Accurate knowledge of tissue composition is important for instance for brachytherapy (BT) treatment planning. However, the accuracy of CT numbers measured with contemporary clinical CT scanners is relatively low since CT numbers are affected by image artifacts. The aim of this work was to estimate the accuracy of CT numbers measured with the Siemens SOMATOM Definition Flash DECT scanner and the accuracy of the resulting volume or mass fractions calculated via the three material decomposition method.

    CT numbers of water, gelatin and a 3rd component (salt, hydroxyapatite or protein powder) mixtures were measured using Siemens SOMATOM Definition Flash DECT scanner. The accuracy of CT numbers was determined by (i) a comparison with theoretical (true) values and (ii) using different measurement conditions (configurations) and assessing the resulting variations in CT numbers. The accuracy of mass fractions determined via the three material decomposition method was estimated by a comparison with mass fractions measured with calibrated scales. The latter method was assumed to provide highly accurate results.

    It was found that (i) axial scanning biased CT numbers for some detector rows. (ii) large volume of air surrounding the measured region shifted CT numbers compared to a configuration where the region was surrounded by water. (iii) highly attenuating object shifted CT numbers of surrounding voxels. (iv) some image kernels caused overshooting and undershooting of CT numbers close to edges. The three material decomposition method produced mass fractions differing from true values by 8% and 15% for the salt and hydroxyapatite mixtures respectively. In this case, the analyzed CT numbers were averaged over a volumetric region. For individual voxels, the volume fractions were affected by statistical noise. The method failed when statistical noise was high or CT numbers of the decomposition triplet were similar.

    Contemporary clinical DECT scanners produced image artifacts that strongly affected the accuracy of the three material decomposition method; the Siemens’ image reconstruction algorithm is not well suited for quantitative CT. The three material decomposition method worked relatively well for averages of CT numbers taken from volumetric regions as these averages lowered statistical noise in the analyzed data. 

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  • 271.
    Ha, Hojin
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Kangwon Natl Univ, South Korea.
    Escobar Kvitting, John-Peder
    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 Thoracic and Vascular Surgery. Linköping University, Center for Medical Image Science and Visualization (CMIV). Oslo Univ Hosp, Norway.
    Dyverfeldt, Petter
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Ebbers, Tino
    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 Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    4D Flow MRI quantification of blood flow patterns, turbulence and pressure drop in normal and stenotic prosthetic heart valves2019In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 55, p. 118-127Article in journal (Refereed)
    Abstract [en]

    Purpose: To assess valvular flow characteristics and pressure drop in a variety of normal and stenotic prosthetic heart valves (PHVs) using 4D Flow MRI. Materials and methods: In-vitro flow phantoms with four different PHVs were studied: Medtronic-Hall tilting disc, St. Jude Medical standard bileaflet (STJM), Medtronic CoreValve Evolut R and Edwards SAPIEN 3. The valvular flow characteristics were investigated in normal and stenotic PHVs by using 4D Flow MRI. Results: The results showed that each valve provided a different amount of signal loss in the 4D Flow MRI. The defect size of the signal loss from each valve was 37.5 mm, 39.0 mm, 37.5 mm and 51.0 mm for the Tilting disk, STJM, SAPIEN 3 and CoreValve, respectively. The 4D Flow MRI-based estimation of the elevation of the pressure drop through the stenotic PHV using both Bernoulli-based and turbulence-based methods correlated well with the true values for the Tilting disc, STJM and SAPIEN 3 valve. However, the obstructive hemodynamics in the stenotic CoreValve was not clearly identified due to the large signal void from the long struts, resulting in a severe underestimation of the pressure drop using 4D Flow MRI. Conclusion: The Tilting disc, STJM and SAPIEN 3 valves provided reasonable estimates of peak velocity, turbulence production and the corresponding pressure drop. In contrast, the large strut of the CoreValve and corresponding signal void prevented accurate measurements of the velocity and turbulence production; therefore, 4D Flow MRI prediction of the pressure drop through the CoreValve was not feasible.

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  • 272. Hagström, Careline
    et al.
    Hult, Peter
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Science & Engineering.
    Intelligenta, robusta och trådlösa sensorer för hem- och primärvården.2004In: Svenska läkaresällskapets riksstämma, 2004, p. 24-27Conference paper (Other academic)
  • 273.
    Hagvall Hörnstedt, Julia
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering.
    Synthesis of Thoracic Computer Tomography Images using Generative Adversarial Networks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of machine learning algorithms to enhance and facilitate medical diagnosis and analysis is a promising and an important area, which could improve the workload of clinicians’ substantially. In order for machine learning algorithms to learn a certain task, large amount of data needs to be available. Data sets for medical image analysis are rarely public due to restrictions concerning the sharing of patient data. The production of synthetic images could act as an anonymization tool to enable the distribution of medical images and facilitate the training of machine learning algorithms, which could be used in practice.

    This thesis investigates the use of Generative Adversarial Networks (GAN) for synthesis of new thoracic computer tomography (CT) images, with no connection to real patients. It also examines the usefulness of the images by comparing the quantitative performance of a segmentation network trained with the synthetic images with the quantitative performance of the same segmentation network trained with real thoracic CT images. The synthetic thoracic CT images were generated using CycleGAN for image-to-image translation between label map ground truth images and thoracic CT images. The synthetic images were evaluated using different set-ups of synthetic and real images for training the segmentation network. All set-ups were evaluated according to sensitivity, accuracy, Dice and F2-score and compared to the same parameters evaluated from a segmentation network trained with 344 real images.

    The thesis shows that it was possible to generate synthetic thoracic CT images using GAN. However, it was not possible to achieve an equal quantitative performance of a segmentation network trained with synthetic data compared to a segmentation network trained with the same amount of real images in the scope of this thesis. It was possible to achieve equal quantitative performance of a segmentation network, as a segmentation network trained on real images, by training it with a combination of real and synthetic images, where a majority of the images were synthetic images and a minority were real images. By using a combination of 59 real images and 590 synthetic images, equal performance as a segmentation network trained with 344 real images was achieved regarding sensitivity, Dice and F2-score.

    Equal quantitative performance of a segmentation network could thus be achieved by using fewer real images together with an abundance of synthetic images, created at close to no cost, indicating a usefulness of synthetically generated images.

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  • 274.
    Haj Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL. Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Medicine and Health Sciences.
    Milos, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery. Neurokirurgi.
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine, Divison of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Optical Guidance for Brain Tumor Stereotactic Biopsy2017Conference paper (Refereed)
  • 275. Order onlineBuy this publication >>
    Haj-Hosseini, Neda
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fluorescence Spectroscopy for Quantitative Demarcation of Glioblastoma Using 5-Aminolevulinic Acid2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Total resection of glioblastoma, the highly malignant brain tumor, is difficult to accomplish due to its diffuse growth and similarity to the surrounding brain tissue. A total resection is proven to increase patient survival. The aim of this thesis was to evaluate fiber-optical based fluorescence spectroscopy for quantitative demarcation of malignant brain tumors during the surgery. Five-aminolevulinic acid (5-ALA) was used as a fluorescence contrast agent that accumulated as protoporphyrin IX (PpIX) in the tumor.

    The method was evaluated at the Department of Neurosurgery, Linköping University Hospital. The patients (n = 22) received an oral dose of 5 mg/kg body weight 5-ALA two hours prior to craniotomy. Measurements with a developed fluorescence spectroscopy system were performed under the general procedure of surgery. The collected fluorescence spectra were quantified by defining a fluorescence ratio and the main challenges of measuring and quantifying spectra were investigated. The fluorescence ratio was compared to visual diagnosis of the surgeon, histopathological examination and ultrasound-based neuronavigation. The main challenges of using a fluorescence spectroscopy system in the operating room were the disturbing ambient light, photobleaching and blood interference which affect the signal quantification. The superimposition of ambient light was removed by modulating the system.

    Using principal component analysis (PCA) the photobleaching sequences could be described by three spectral components of autofluorescence, PpIX fluorescence and blue-shift. To investigate the photobleaching induced prior to the measurements, a dynamic model was developed based on the PCA derived spectral components. Modulation and increased power of the excitation light resulted in a faster photobleaching; however, photobleaching was saturated at higher excitation powers. The system was adjusted to induce minimal photobleaching. In addition, effect of blood absorption on the fluorescence spectrum was investigated experimentally by placing blood drops on skin and theoretically by using Beer-Lambert law. The theoretical model was used to compensate for the distorted fluorescence ratio. According to the theoretical model of blood interference, a total 300 µm blood layer blocked the brain fluorescence signal totally and when the fluorescence signal was partially blocked, the fluorescence ratio was overestimated. The fluorescence ratio was corrected for blood layers thinner than 50 µm.

    The tissue in and around the tumor was categorized into necrosis, low and high grade tumor and gliosis. The median fluorescence ratio confirmed with histopathological examination (n = 45) had a lower fluorescence ratio for low grade malignancies (0.3) than high grade malignancies (2.4) (p < 0.05). Gliosis (1.6) and necrosis (1.0) showed a moderate fluorescence ratio. Ultrasound-based navigation in combination with fluorescence spectroscopy showed improvement in the results; however, a more extensive study is needed to confirm benefits of the method combination. In conclusion, fluorescence spectroscopy of 5-ALA induced PpIX provided an objective method for differentiating tumor from the healthy tissue intra-operatively. Fluorescence ratios were indicative of tissue type and tumor malignancy degree.

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    Fluorescence Spectroscopy for Quantitative Demarcation of Glioblastoma Using 5-Aminolevulinic Acid
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  • 276.
    Haj-Hosseini, Neda
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Optical Coherence Tomography for 3D Cancer Imaging2015Conference paper (Refereed)
    Abstract [en]

    Optical coherence tomography (OCT) is an advanced optical imaging technology for imaging material based on their optical scattering properties. OCT provides high-resolution 2D (en face or cross-sectional) and 3D images from the surface and subsurface tissue microstructures within a few mm depth. The first article on OCT was published in 1991 by D. Huang et. al. [1]. More than 15000 articles have been published since 1991 on different applications of OCT. However, the technique has so far entered the clinical routine only within ophthalmology and cardiovascular imaging in which the majority of the articles have been published [2]. OCT is a capable technology with great potentials for further translational research and implementation in additional clinical fields. One potential application of OCT is within cancer detection intraoperatively or post operatively for providing an on-site fast diagnosis. In this study, OCT’s ability to differentiate histology and pathology for application in tissue identification, pathological diagnosis and cancer staging was investigated.

    Material and Method:

    The technology uses near infrared or infrared light for imaging tissue structures that havedifferent optical scattering properties. The technique is based on low coherence interferometryand measures the backscattered light from the tissue. The scanning dimensions and resolutions are dependent on the type of the OCT system. In this study a TELESTO IITM system (Thorlabs, Inc., NJ, USA) was used. The maximum lateral and axial resolution of the system were 13 and 5.5 μm, respectively. A total of eleven patients undergoing brain, thyroid and parathyroid surgery were included in the study.

    Results:

    Figure 1 shows a 3D scan of the fingertip taken by the described OCT system as an example. The skin layers (epidermis and dermis) including the fingerprint and a sweat gland (the spiral structure) are visible. Various tissue type specimens involved in thyroid and parathyroid surgeries and brain tumor surgery were evaluated.

  • 277.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Behm, Pascal
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology. University of Applied Sciences in Northwest Switzerland.
    Shabo, Ivan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fluorescence spectroscopy using indocyanine green for lymph node mapping2014Conference paper (Refereed)
    Abstract [en]

    The principles of cancer treatment has for years been radical resection of the primary tumor. In the oncologic surgeries where the affected cancer site is close to the lymphatic system, it is as important to detect the draining lymph nodes for metastasis (lymph node mapping). As a replacement for conventional radioactive labeling, indocyanine green (ICG) has shown successful results in lymph node mapping; however, most of the ICG fluorescence detection techniques developed are based on camera imaging. In this work, fluorescence spectroscopy using a fiber-optical probe was evaluated on a tissue-like ICG phantom with ICG concentrations of 6-64 μM and on breast tissue from five patients. Fiber-optical based spectroscopy was able to detect ICG fluorescence at low intensities; therefore, it is expected to increase the detection threshold of the conventional imaging systems when used intraoperatively. The probe allows spectral characterization of the fluorescence and navigation in the tissue as opposed to camera imaging which is limited to the view on the surface of the tissue

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  • 278.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Gimm, Oliver
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Höög, Anders
    Linköping University, Department of Clinical and Experimental Medicine, Divison of Neurobiology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Johansson, Kenth
    Landstinget i Kalmar län och Sahlgrenska universitetssjukhus, Västra Götalandsregion.
    Optiska metoder för identifiering av bisköldkörtel och sköldkörtel2017Conference paper (Refereed)
    Abstract [sv]

    Identifiering av bisköldkörtlar är viktigt vid sköldkörtel- och bisköldkörtelkirurgi och kan vara svårt då de liknar omgivande vävnad såsom fett och lymfkörtlar. Peroperativ detektering av dessa vävnader kan förbättra möjligheten att bota patienter med hyperparathyroidism och minska risken för bisköldkörtelskador vid thyroideakirurgi. Optiska metoder är potentiella tekniker för att möjliggöra detta. Optiska tekniker utvärderades på vävnadsprover från patienter vid bisköldkörtel- och sköldkörteloperation. Teknikerna bestod av nära infraröd fluorescens (NIR) spektroskopi och optisk koherenstomografi (OCT) som ger en bild av vävnadens mikrostruktur liknande till ultraljud med högre upplösning (10 μm).

  • 279.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Kistler, Benjamin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. University of Applied Sciences in Northwest Switzerland.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Development and characterization of a brain tumor mimicking fluorescence phantom   2014In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 8945, p. 1-6, article id 894505Article in journal (Refereed)
    Abstract [en]

    Fluorescence guidance using 5-aminolevulinic acid (5-ALA) for brain tumor resection is a recent technique applied to the highly malignant brain tumors. Five-ALA accumulates as protoporphyrin IX fluorophore in the tumor cells in different concentrations depending on the tumor environment and cell properties. Our group has developed a fluorescence spectroscopy system used with a hand-held probe intra-operatively. The system has shown improvement of fluorescence detection and allows quantification that preliminarily correlates with tumor malignancy grade during surgery. However, quantification of fluorescence is affected by several factors including the initial fluorophore concentration, photobleaching due to operating lamps and attenuation from the blood. Accordingly, an optical phantom was developed to enable controlled fluorescence measurements and evaluation of the system outside of the surgical procedure. The phantom mimicked the optical properties of glioma at the specific fluorescence excitation wavelength when different concentrations of the fluorophore were included in the phantom. To allow evaluation of photobleaching, kinetics of fluorophore molecules in the phantom was restricted by solidifying the phantoms. Moreover, a model for tissue autofluorescence was added. The fluorescence intensity’s correlation with fluorophore concentration in addition to the photobleaching properties were investigated in the phantoms and were compared to the clinical data measured on the brain tumor.

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  • 280.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Milos, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hildesjö, Camilla
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Hallbeck, Martin
    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 Pathology and Clinical Genetics.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Fluorescence spectroscopy and optical coherence tomography for brain tumor detection2016Conference paper (Refereed)
    Abstract [en]

    Resection of brain tumor is a challenging task as the tumor does not have clear borders and the malignant types specifically have often a diffuse and infiltrative pattern of growth. Recently, neurosurgical microscopes have been modified to incorporate fluorescence modules for detection of tumor when 5-aminolevulinic acid (5-ALA) is used as a contrast. We have in combination with the fluorescence microscopes implemented and evaluated a fluorescence spectroscopy based handheld probe for detecting the 5-aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX) in the gliomas in 50 patients intraoperatively. The results show a significantly high sensitivity for differentiating tumor from the healthy tissue and distinguished fluorescence intensity levels in the tumor cell infiltration zone around the tumor. However, knowledge on association of the quantified fluorescence signals specifically in the intermediate inflammatory zone with the infiltrative tumor cells can be complemented with volumetric tissue imaging and a higher precision histopathological analysis. In this work, a spectral domain optical coherence tomography (OCT) system with central wavelength of 1325nm has been used to image the tissue volume that the fluorescence is collected from and is evaluated against histopathological analysis for a higher precision slicing. The results show that although healthy brain has a homogenous microstructure in the OCT images, the brain tumor shows a distinguished texture in the images correlated with the PpIX fluorescence intensity and histopathology.

  • 281.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Milos, Peter
    Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery. Linköping University, Faculty of Science & Engineering.
    Hallbeck, Martin
    Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    A Multipurpose Guidance Probe for Stereotactic Biopsy Procedures2016Conference paper (Refereed)
  • 282.
    Haj-Hosseini, Neda
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Milos, Peter
    Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hildesjö, Camilla
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Hallbeck, Martin
    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 Pathology and Clinical Genetics.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Detection of brain tumor using fluorescence and optical coherence tomography2015Conference paper (Refereed)
    Abstract [en]

    Resection of brain tumor is a challenging task as the tumor does not have clear borders and the malignant types specifically have often a diffuse and infiltrative pattern of growth. We have previously implemented and evaluated a fluorescence spectroscopy based handheld probe for detecting the 5-aminolevulinic acid induced protoporphyrin IX (PpIX) in the gliomas. To add another dimension to the brain tumor detection and volumetric analysis of the tissue that exhibits fluorescence, optical coherence tomography was investigated on tumor specimens.

    Material and Methods:

    A fluorescence microscopy and a spectroscopy system as reported previously were used for detecting the fluorescence signals [1, 2]. A total of 50 patients have been included for intraoperative assessment of the tumor borders using the fluorescence techniques. A spectral domain OCT imaging system (TELESTO II, Thorlabs, Inc., NJ, USA) with central wavelength of 1325 nm was used to study the tissue microstructure post operatively. The system has a resolution of 13 and 5.5 μm in the lateral and axial directions, respectively. Tissue specimens from three patients undergoing brain tumor surgery were studied using the OCT system.

    Results and Conclusion:

    Using fluorescence spectroscopy the tumor could be detected with a sensitivity of 0.84 which was significantly higher than that of the surgical microscope (0.30). Brain tissue appeared rather homogeneous in the OCT images however the highly malignant tissue showed a clear structural difference from the non-malignant or low malignant brain tumor tissue which could be related to the fluorescence signal intensities.

  • 283.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Medicine and Health Sciences.
    Petersson, Pernilla
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Gimm, Oliver
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Shabo, Ivan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Optical Coherence Tomography for Pathological Analysis of Thyroid2016Conference paper (Refereed)
  • 284.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Andersson-Engel, Stefan
    Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fluorescence guided resection of glioblastoma multiforme using an optical touch pointer-Clinical evaluation2010Conference paper (Refereed)
  • 285.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hallbeck, Martin
    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.
    Milos, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Stereotactic Brain Tumor Optical Biopsy2018Conference paper (Other academic)
    Abstract [en]

    To provide guidance for targeting diagnostic tumor tissue and to avoid vessel rupture during the biopsy procedure an application specific fiber optic probe was devel-oped. The setup incorporated an in-house developed fluorescence spectroscopy system for 5-aminolevulinic acid (5-ALA) induced protopophyrin IX (PpIX) for detection in the tumor, and laser Doppler flowmeter (LDF) system for measurement of blood perfusion. Fluorescence and blood flow were recorded millimeter-wise towards the pre-calculated target. In conclusion, the optical probe made real-time detection of tumor possible and has a potential for vessel detection during the biopsy procedures. Moreover, the PpIX fluorescence, autofluorescence and blood flow in the tumor could be studied at precise positions in the brain and the tumor. In the next step, further anal-ysis will be added.

  • 286.
    Haj-Hosseini, Neda
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hallbeck, Martin
    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 Pathology and Clinical Genetics.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Low dose 5-aminolevulinic acid: Implications in spectroscopic measurements during brain tumor surgery2015In: Photodiagnosis and Photodynamic Therapy, ISSN 1572-1000, E-ISSN 1873-1597, Vol. 12, no 2, p. 209-214Article in journal (Refereed)
    Abstract [en]

    Background

    Using 5-aminolevulinic acid (ALA) as an intraoperative fluorescence contrast has been proven to improve the resection of glioblastoma and contribute to prolonged patient survival. ALA accumulates as protoporphyrin IX (PpIX) in the tumor cells and is administered in an advised dose of 20 mg/kg body weight (b.w.) for brain tumor resection using fluorescence surgical microscopes. PpIX fluorescence availability and intensities of a four folds lower ALA dose (5 mg/kg b.w.) has been investigated in glioblastomas and skin using a spectroscopy system adapted for surgical guidance.

    Methods

    A total of 30 adult patients diagnosed with high grade gliomas were included in the analysis. ALA was orally administered in doses of 5 mg/kg b.w. (n = 15) dissolved in orange juice or 20 mg/kg b.w. (n = 15) dissolved in water. A fluorescence spectroscopy system with a handheld fiber-optical probe was used for performing the quantitative fluorescence measurements.

    Results

    The binominal comparison of the diagnostic performance parameters showed no significant statistical difference (p > 0.05). The median fluorescence values in tumor were 2-3 times higher for the high ALA dose group. No PpIX was detected in the skin of the patients in the low dose group (0/4) while PpIX was detected in the skin of the majority of the patients in the high ALA dose group (13/14).

    Conclusions

    Application of 5 mg/kg ALA was evaluated as equally reliable as the higher dose regarding the diagnostic performance when guidance was performed using a spectroscopic system. Moreover, no PpIX was detected in the skin of the patients.

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  • 287.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Richter, Johan
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Kobayashi Frisk, Lisa
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Milos, Peter
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Clinical pathology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Fluorescence Guidance for Brain Tumor Biopsies2018Conference paper (Refereed)
    Abstract [en]

    To provide guidance during stereotactic biopsy in brain tumors, fluorescence spectroscopy was used in ten patients. It was shown that the fiber optical probe could provide real-time guidance with clear fluorescence in all patients.

  • 288.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Milos, Peter
    Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Hallbeck, Martin
    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.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    5-ALA fluorescence and laser Doppler flowmetry for guidance in a stereotactic brain tumor biopsy2018In: Biomedical Optics Express, E-ISSN 2156-7085, Vol. 9, no 5, p. 2284-2296Article in journal (Refereed)
    Abstract [en]

    A fiber optic probe was developed for guidance during stereotactic brain biopsy procedures to target tumor tissue and reduce the risk of hemorrhage. The probe was connected to a setup for the measurement of 5-aminolevulinic acid (5-ALA) induced fluorescence and microvascular blood flow. Along three stereotactic trajectories, fluorescence (n = 109) and laser Doppler flowmetry (LDF) (n = 144) measurements were done in millimeter increments. The recorded signals were compared to histopathology and radiology images. The median ratio of protoporphyrin IX (PpIX) fluorescence and autofluorescence (AF) in the tumor was considerably higher than the marginal zone (17.3 vs 0.9). The blood flow showed two high spots (3%) in total. The proposed setup allows simultaneous and real-time detection of tumor tissue and microvascular blood flow for tracking the vessels.

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  • 289.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Medicine and Health Sciences.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Milos, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hallbeck, Martin
    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 Pathology and Clinical Genetics.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Optical guidance for stereotactic brain tumor biopsy procedures-preliminary clinical evaluation2017Conference paper (Refereed)
    Abstract [en]

    During stereotactic biopsy on suspected tumors in the brain, tissue samples are harvested to determine the malignancy. To provide guidance for finding the diagnostic tumor sites and to avoid vessel rupture, an application specific probe was developed. The setup incorporated spectroscopy for detection of 5-aminolevulinic acid induced protoporphyrin (PpIX) fluorescence and blood flow using laser Doppler flowmetry. The PpIX fluorescence was significantly different in the tumor compared to the gliotic marginal zone (p < 0.05). In conclusion, the systems made real-time tumor detection and vessel tracking possible. Moreover, the autofluorescence and blood perfusion could be studied in the tumor.

  • 290.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Olivecrona, Magnus
    Department of Neurosurgery, Umeå University.
    Hillman, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hallbeck, Martin
    Linköping University, Department of Clinical and Experimental Medicine, Experimental Pathology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fluorescence guided spectroscopy versus fluorescence microscopy for brain tumor resection2013Conference paper (Other academic)
  • 291.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fluorescence spectroscopy for ALA-guided glioblastoma resection using a fiber-optical probe2012Conference paper (Refereed)
  • 292.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Medicine and Health Sciences.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Medicine and Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Photodiagnostics in Brain Tumor Surgery2014In: Medicinteknikdagarna, Göteborg, 14-16 oktober, 2014: Sammanfattningar, Göteborg: Svensk förening för medicinsk teknik och fysik , 2014Conference paper (Refereed)
    Abstract [en]

    Since getting approved for clinical application in neurosurgery 5-aminolevulinic acid (ALA), that is a fluorescence contrast agent, has attracted the interest of many neurosurgical clinics to implement it in their surgical routine. ALA naturally exists in the body and the external administration of the substance induces accumulation of a fluorophore known as protoporphyrin IX (PpIX) in the malignant cells due to a broken blood brain barrier and the altered enzyme levels in the brain tumor. The detection and visualization of PpIX in the clinical routine is conventionally performed using a modified neuro surgical microscope. As a complementary technique for detection of ALA-induced fluorescence and to perform objective and quantitative measurements, our group has developed a spectroscopy system adapted to the equipment in the operating room. The system includes a hand-held fiber optic probe which can be integrated in the neuronavigation and stereotactic systems. The main advantages of the system are the ease of use, high sensitivity, quantitative fluorescence detection and the possibility of applying a low dose of fluorescence contrast agent while obtaining equally reliable results as with the high dose. In this contribution we present our experience, gains and challenges from implementation of the system during brain tumor surgery in forty adult patients. The methods and systems are currently being adapted for implementation during operations of pediatric brain tumors.

  • 293.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Health Sciences.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Quantitative ALA photodiagnostics in Neurosurgery2014Conference paper (Other academic)
  • 294.
    Haj-Hosseini, Neda
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Compensation of blood interference in fiber-optical based fluorescence guided resection of brain tumor2011Conference paper (Refereed)
  • 295.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Stepp, Herbert
    Ludwig Maximilians Universitet, München.
    Markwardt, Niklas
    Ludwig Maximilians Universitet, München.
    Gimm, Oliver
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Shabo, Ivan
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Surgery in Linköping.
    Optical biopsy during thyroid and parathyroid surgery2015Conference paper (Refereed)
  • 296.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Optical Coherence Tomography as a Future Modality in Digital Pathology2015Conference paper (Other academic)
  • 297.
    Hallberg, Inger
    et al.
    Institutionen för vårdvetenskap och hälsa, Göteborgs Universitet, Centrum för personcentrerad vård, Sahlgrenska akademin, Göteborgs Universitet.
    Taft, Charles
    Institutionen för vårdvetenskap och hälsa, Göteborgs Universitet, Centrum för personcentrerad vård, Sahlgrenska akademin, Göteborgs Universitet.
    Ranerup, Agneta
    Avdelningen för informatik, Göteborgs Universitet, Centrum för personcentrerad vård, Sahlgrenska akademin, Göteborgs Universitet.
    Bengtsson, Ulrika
    Institutionen för vårdvetenskap och hälsa, Göteborgs Universitet, Centrum för personcentrerad vård, Sahlgrenska akademin, Göteborgs Universitet.
    Hoffman, Mikael
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences. Stiftelsen NEPI, Linköping .
    Höfer, Stefan
    Department of Medical Psychology, Innsbruck Medical University, Innsbruck, Austria.
    Kasperowski, Dick
    Institutionen för filosofi, lingvistik och vetenskapsteori, Göteborgs Universitet.
    Mäkitalo, Åsa
    Institutionen för pedagogik, kommunikation och lärande, Göteborgs Universitet.
    Lundin, Mona
    Institutionen för pedagogik, kommunikation och lärande, Göteborgs Universitet.
    Ring, Lena
    Centrum för forsknings- och bioetik, Uppsala Universitet, Enheten för läkemedelsanvändning, Läkemedelsverket, Uppsala.
    Rosenqvist, Ulf
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in West Östergötland, Department of Medical Specialist in Motala.
    Kjellgren, Karin I
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Health Sciences. Institutionen för vårdvetenskap och hälsa, Göteborgs Universitet, Centrum för personcentrerad vård, Sahlgrenska akademin, Göteborgs Universitet.
    Phases in development of an interactive mobile phone-based system to support self-management of hypertension2014In: Integrated Blood Pressure Control, ISSN 1178-7104, E-ISSN 1178-7104, Vol. 7, p. 19-28Article in journal (Refereed)
    Abstract [en]

    Hypertension is a significant risk factor for heart disease and stroke worldwide. Effective treatment regimens exist; however, treatment adherence rates are poor (30%–50%). Improving self-management may be a way to increase adherence to treatment. The purpose of this paper is to describe the phases in the development and preliminary evaluation of an interactive mobile phone-based system aimed at supporting patients in self-managing their hypertension. A person-centered and participatory framework emphasizing patient involvement was used. An interdisciplinary group of researchers, patients with hypertension, and health care professionals who were specialized in hypertension care designed and developed a set of questions and motivational messages for use in an interactive mobile phone-based system. Guided by the US Food and Drug Administration framework for the development of patient-reported outcome measures, the development and evaluation process comprised three major development phases (1, defining; 2, adjusting; 3, confirming the conceptual framework and delivery system) and two evaluation and refinement phases (4, collecting, analyzing, interpreting data; 5, evaluating the self-management system in clinical practice). Evaluation of new mobile health systems in a structured manner is important to understand how various factors affect the development process from both a technical and human perspective. Forthcoming analyses will evaluate the effectiveness and utility of the mobile phone-based system in supporting the self-management of hypertension.

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  • 298.
    Han, Songfeng
    et al.
    Institute of Optics, University of Rochester.
    Johansson, Johannes
    ICFO- Institut de Ciències Fotòniques.
    Mireles, Miguel
    ICFO- Institut de Ciències Fotòniques.
    Proctor, Ashley R
    Department of Biomedical Engineering, University of Rochester.
    Hoffman, Michael D
    Department of Biomedical Engineering, University of Rochester.
    Vella, Joseph B
    Department of Biomedical Engineering, University of Rochester.
    Benoit, Danielle S W
    Department of Biomedical Engineering, University of Rochester.
    Durduran, Turgut
    ICFO- Institut de Ciències Fotòniques.
    Choe, Regine
    Department of Biomedical Engineering, University of Rochester.
    Non-contact scanning diffuse correlation tomography system for three-dimensional blood flow imaging in a murine bone graft model.2015In: Biomedical Optics Express, ISSN 2156-7085, E-ISSN 2156-7085, Vol. 6, no 7Article in journal (Refereed)
    Abstract [en]

    A non-contact galvanometer-based optical scanning system for diffuse correlation tomography was developed for monitoring bone graft healing in a murine femur model. A linear image reconstruction algorithm for diffuse correlation tomography was tested using finite-element method based simulated data and experimental data from a femur or a tube suspended in a homogeneous liquid phantom. Finally, the non-contact system was utilized to monitor in vivo blood flow changes prior to and one week after bone graft transplantation within murine femurs. Localized blood flow changes were observed in three mice, demonstrating a potential for quantification of longitudinal blood flow associated with bone graft healing.

  • 299. Order onlineBuy this publication >>
    Haraldsson, Henrik
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences.
    Assessment of Myocardial Function using Phase Based Motion Sensitive MRI2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Quantitative assessment of myocardial function is a valuable tool for clinical applications and physiological studies. This assessment can be acquired using phase based motion sensitive magnetic resonance imaging (MRI) techniques. In this thesis, the accuracy of these phase based motion sensitive MRI techniques is investigated, and modifications in acquisition and post-processing are proposed.

    The strain rate of the myocardium can be used to evaluate the myocardial function. However, the estimation of strain rate from the velocity data acquired with phase-contrast MRI (PC-MRI) is sensitive to noise. Estimation using normalized convolution showed, however, to reduce this sensitivity to noise and to minimize the influence of non-myocardial tissue which could impair the result.

    Strain of the myocardium is another measure to assess myocardial function. Strain can be estimated from the myocardial displacement acquired with displacement encoding with stimulated echo (DENSE). DENSE acquisition can be realized with several different encoding strategies. The choice of encoding scheme may make the acquisition more or less sensitive to different sources of error. Two potential sources of errors in DENSE acquisition are the influence of the FID and of  the off-resonance effects. Their influence on DENSE were investigated to determine suitable encoding strategies to reduce their influence and thereby improve the measurement accuracy acquired.

    The quality of the DENSE measurement is not only dependent on the accuracy, but also the precision of the measurement. The precision is affected by the SNR and thereby depends on flip angle strategies, magnetic field strength and spatial variation of the receiver coil sensitivity. A mutual comparison of their influence on SNR in DENSE was therefore performed and could serve as a guideline to optimize parameters for specific applications.

    The acquisition time is often an important factor, especially in clinical applications where it affects potential patient discomfort and patient through-put. A multiple-slice DENSE acquisition was therefore presented, which allows the acquisition of strain values according to the 16-segment cardiac model within a single breath-hold, instead of the conventional three breath-holds.

    The DENSE technique can also be adapted toward comprehensive evaluation of the heart in the form of full three-dimensional three-directional acquisition of the displacement. To estimate the full strain tensor from these data, a novel post-processing technique using a polynomial was investigated. The method yielded accurate results on an analytical model and \textit{in-vivo} strains obtained agreed with previously reported myocardial strains in normal volunteers.

    List of papers
    1. Improved estimation and visualization of two-dimensional myocardial strain rate using MR velocity mapping
    Open this publication in new window or tab >>Improved estimation and visualization of two-dimensional myocardial strain rate using MR velocity mapping
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    2008 (English)In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 28, no 3, p. 604-611Article in journal (Refereed) Published
    Abstract [en]

    Purpose: To estimate regional myocardial strain rate, with reduced sensitivity to noise and velocities outside the region of interest, and provide a visualization of the spatial variation of the obtained tensor field within the myocardium. Materials and Methods: Myocardial velocities were measured using two-dimensional phase contrast velocity mapping. Velocity gradients were estimated using normalized convolution and the calculated 2D strain rate tensor field was visualized using a glyph representation. Validation utilized a numerical phantom with known strain rate distribution. Strain rate glyph visualizations were created for normal myocardium in both systole and diastole and compared to a patient with an anteroseptal infarction. Results: In the phantom study the strain rate calculated with normalized convolution showed a very good agreement with the analytic solution, while traditional methods for gradient estimation were shown to be sensitive to both noise and surrounding velocity data. Normal myocardium showed a homogenous strain rate distribution, while a heterogeneous strain rate can be clearly seen in the patient data. Conclusion: The proposed approach for quantification and visualization of the regional myocardial strain rate can provide an objective measure of regional myocardial contraction and relaxation that may be valuable for the assessment of myocardial heart disease. © 2008 Wiley-Liss, Inc.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-43136 (URN)10.1002/jmri.21471 (DOI)000259106900007 ()71981 (Local ID)71981 (Archive number)71981 (OAI)
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
    2. Influence of the FID and off-resonance effects in dense MRI
    Open this publication in new window or tab >>Influence of the FID and off-resonance effects in dense MRI
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    2011 (English)In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 65, no 4, p. 1104-1112Article in journal (Refereed) Published
    Abstract [en]

    Accurate functional measurement in cardiovascular diseases is important as inaccuracy may compromise diagnostic decisions. Cardiac function can be assessed using displacement encoding with stimulated echoes, resulting in three signal components. The free induction decay (FID), arising from spins undergoing T1-relaxation, is not displacement encoded and impairs the displacement acquired. Techniques for suppressing the FID exist; however, a residual will remain. The effect of the residual is difficult to distinguish and investigate in vitro and in vivo. In this work, the influence of the FID as well as of off-resonance effects is evaluated by altering the phase of the FID in relation to the stimulated echo. The results show that the FID and off-resonance effects can impair the accuracy of the displacement measurement acquired. The influence of the FID can be avoided by using an encoded reference. We therefore recommend the assessment of this influence of the FID for each displacement encoding with stimulated echoes protocol.

    Place, publisher, year, edition, pages
    Wiley, 2011
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-60266 (URN)10.1002/mrm.22692 (DOI)000288612000023 ()
    Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2017-12-12
    3.
    The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
    4. Single Breath Hold Multiple Slice DENSE MRI
    Open this publication in new window or tab >>Single Breath Hold Multiple Slice DENSE MRI
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    2010 (English)In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 63, no 5, p. 1411-1414Article in journal (Refereed) Published
    Abstract [en]

    A method to acquire multiple displacement encoded slices within asingle breath hold is presented. Efficiency is improved overconventional Displacement ENcoding with Stimulated Echoes (DENSE) without compromising image quality by read-out of multiple slices inthe same cardiac cycle, thus utilizing the position encoded stimulatedecho available in the whole heart. The method was evaluated bycomparing strain values obtained using the proposed method to strainvalues obtained by conventional separate breath hold single-sliceDENSE acquisitions. Good agreement (Lagrangian E2 strainbias=0.000, 95% limits of agreement ±0.04,root-mean-square-difference 0.02 (9.4% of the mean end-systolic E2)) was found between the methods, indicating that the proposedmethod can replace a multiple breath hold acquisition. Eliminating theneed for multiple breath holds reduces the risk of changes in breathhold positions or heart rate, results in higher patient comfort andfacilitates inclusion of DENSE in a clinical routine protocol.

    Place, publisher, year, edition, pages
    John Wiley and Sons, Ltd, 2010
    Keywords
    DENSE, strain, multi-slice, breath hold, cardiac function
    National Category
    Medical Laboratory and Measurements Technologies
    Identifiers
    urn:nbn:se:liu:diva-51974 (URN)10.1002/mrm.22305 (DOI)000277098100030 ()
    Available from: 2009-11-25 Created: 2009-11-25 Last updated: 2017-12-12Bibliographically approved
    5. Myocardial strains from 3D DENSE magnetic resonance imaging
    Open this publication in new window or tab >>Myocardial strains from 3D DENSE magnetic resonance imaging
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The ability to measure and quantify myocardial motion and deformation provides a useful tool to assist in the diagnosis, prognosis and management of heart disease. The recent development of magnetic resonance imaging methods, such as harmonic phase and displacement encoding with stimulated echoes (DENSE), make detailed non-invasive 3D transmural kinematic analyses of human myocardium possible in the clinic and for research purposes. As data acquisition technologies improve, quantification methods for cardiac kinematics need to be adapted and validated on the new types of data. In the present paper, a previously presented polynomial method for cardiac strain quantification is extended to quantify 3D strains from DENSE magnetic resonance imaging data. The method yields accurate results when validated against an analytical standard, and is applied to in vivo data from a healthy  human heart. The polynomial field is capable of resolving the measured material positions from the in vivo data, and the obtained in vivo strains agree

    Keywords
    Strain, 3D, myocardium, DENSE, transmural
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-60201 (URN)
    Available from: 2010-10-07 Created: 2010-10-07 Last updated: 2016-03-14
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    Assessment of Myocardial Function using Phase Based Motion Sensitive MRI
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  • 300.
    Haraldsson, Henrik
    et al.
    Univ Calif San Francisco, CA 94143 USA.
    Kefayati, Sarah
    Univ Calif San Francisco, CA 94143 USA.
    Ahn, Sinyeob
    Siemens Healthcare, Germany.
    Dyverfeldt, Petter
    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 Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Lantz, Jonas
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Laub, Gerhard
    Siemens Healthcare, Germany.
    Ebbers, Tino
    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 Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Saloner, David
    Univ Calif San Francisco, CA 94143 USA; Vet Affairs Med Ctr, CA 94121 USA.
    Assessment of Reynolds stress components and turbulent pressure loss using 4D flow MRI with extended motion encoding2018In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 79, no 4, p. 1962-1971Article in journal (Refereed)
    Abstract [en]

    PurposeTo measure the Reynolds stress tensor using 4D flow MRI, and to evaluate its contribution to computed pressure maps. MethodsA method to assess both velocity and Reynolds stress using 4D flow MRI is presented and evaluated. The Reynolds stress is compared by cross-sectional integrals of the Reynolds stress invariants. Pressure maps are computed using the pressure Poisson equationboth including and neglecting the Reynolds stress. ResultGood agreement is seen for Reynolds stress between computational fluid dynamics, simulated MRI, and MRI experiment. The Reynolds stress can significantly influence the computed pressure loss for simulated (eg, -0.52% vs -15.34% error; Pamp;lt;0.001) and experimental (eg, 30611 vs 203 +/- 6 Pa; Pamp;lt;0.001) data. A 54% greater pressure loss is seen at the highest experimental flow rate when accounting for Reynolds stress (Pamp;lt;0.001). Conclusion4D flow MRI with extended motion-encoding enables quantification of both the velocity and the Reynolds stress tensor. The additional information provided by this method improves the assessment of pressure gradients across a stenosis in the presence of turbulence. Unlike conventional methods, which are only valid if the flow is laminar, the proposed method is valid for both laminar and disturbed flow, a common presentation in diseased vessels. Magn Reson Med 79:1962-1971, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.

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