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  • 301.
    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.

  • 302. 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
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    (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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  • 303.
    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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  • 304.
    Hatamie, Amir
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering. Shvrif Univ Technol, Iran.
    Angizi, Shayan
    Shvrif Univ Technol, Iran.
    Kumar, Saurabh
    Indian Inst Sci, India; Delhi Technol Univ, India.
    Pandey, Chandra Mouli
    Delhi Technol Univ, India.
    Simchi, Abdolreza
    Shvrif Univ Technol, Iran.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Malhotra, Bansi D.
    Delhi Technol Univ, India.
    Review-Textile Based Chemical and Physical Sensors for Healthcare Monitoring2020In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 167, no 3, article id 037546Article, review/survey (Refereed)
    Abstract [en]

    The emergence of textile-based wearable sensors as light-weight portable devices to monitor desired parameters, has recently gained much interest and has led to the development of flexible electronics on non-rigid substrates. The flexible biosensors may result in improved sports performance, to monitor the desired bodies for injuries, improved clinical diagnostics and monitor biological molecules and ions in biological fluids such as saliva, sweat. In addition, they could help users with different types of disorders such as blindness. In this context, new composite and nanomaterials have been found to be promising candidates to obtain improved performance of the textile based wearable devices and to optimize the structures for intimate contact with the skin for better functionality. This review aims to provide the most recent cutting-edge information on emergence, fabrication, materials, and applications of chemical and physical flexible and stretchable textile-based (bio)sensors. Besides this, we discusss the recent key innovations and applications of textile-based sensors in healthcare.

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  • 305.
    Haufe, William
    et al.
    Department of Radiology, University of California, San Diego, San Diego, CA, United states.
    Hooker, Jonathan
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Schlein, Alexandra
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Szeverenyi, Nikolaus
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Borga, Magnus
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Advanced MR Analytics AB, Linköping, Sweden.
    Dahlqvist Leinhard, Olof
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Radiation Physics. Advanced MR Analytics AB, Linköping, Sweden.
    Romu, Thobias
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Advanced MR Analytics AB, Linköping, Sweden.
    Tunón, Patrik
    Advanced MR Analytics AB, Linköping, Sweden.
    Horgan, Santiago
    Surgery, University of California, San Diego, San Diego, CA, United States.
    Jacobsen, Garth
    Surgery, University of California, San Diego, San Diego, CA, United States.
    Schwimmer, Jeffrey B
    University of California, San Diego, San Diego, CA, United States.
    Reeder, Scott B
    University of Wisconsin, Madison, Madison, WI, United States.
    Sirlin, Claude B.
    Department of Radiology, University of California, San Diego, San Diego, CA, United States.
    Feasibility of an automated tissue segmentation technique in a longitudinal weight loss study2016Conference paper (Other academic)
    Abstract [en]

    To address the problems inherent in manual methods, a novel, semi-automated tissue segmentation image analysis technique has been developed. The purpose of this study was to demonstrate the feasibility and describe preliminary observations of applying this technique to quantify and monitor longitudinal changes in abdominal adipose tissue and thigh muscle volume in obese adults during weight loss. Abdominal adipose tissue and thigh muscle volume decreased during weight loss. As a proportion of body weight, adipose tissue volumes decreased during weight loss. By comparison, as a proportion of body weight, thigh muscle volume increased.

  • 306.
    Helmersson, Teresa
    Linköping University, Department of Medical and Health Sciences.
    Evaluation of Synthetic MRI for Clinical Use2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Conventional Magnetic Resonance Imaging (MRI) is a qualitative method for obtaining images of softtissues in patients. Conventional MRI is the standard method used today and it results in gray-scaleimages in which the different magnetic properties of biological tissues determine the image contrast. However, the magnitude of the measured signal is only relative and therefore not directlycomparable between images. Synthetic MRI is a relatively new technique which can be used to postsynthesizedifferent images based on absolute measurement of several magnetic properties oftissues. Synthetic MRI can therefore provide quantitative information together with the contrastimages.

    In order to use synthetic MRI clinically an evaluation of the image quality and diagnostic ability isrequired. The purpose of this thesis is to evaluate if synthetic MRI and conventional MRI produceimages with equal contrast.

    A study was designed and conducted for statistical evaluation of contrast and Contrast-to-Noise Ratio(CNR) generated with different imaging methods. A total of 22 patients were examined using bothconventional MRI and synthetic MRI and the results were pairwise analyzed.

    The contrast and CNR could not be stated as equal for the imaging methods. Typically the contrastwas higher in the synthetic images for the T1 and T2 weighted images. This was not observed withCNR which suggests that the noise is higher in the synthetic images. The higher contrast obtained insynthetic images resulted in a better separation of different tissues using synthetic MRI. Thesynthetic T2 FLAIR images contained artifacts that are not good for clinical use. However the fact thatthe different imaging methods produce different image quality is not proven to be clinically decisive.

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  • 307.
    Hemm, Simone
    et al.
    Institute for Medical and Analytical Technologies (IMA), FHNW, Switzerland.
    Richter, Johan C.O.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Zsigmond, Peter
    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.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Optical measurements for guidance during deep brain stimulation implantation2011Conference paper (Refereed)
  • 308.
    Hemm, Simone
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Richter, Johan
    Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL. Linköping University, Department of Biomedical Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Laser doppler for guidance during DBS-typical optical trajectories toward Vim and STN2012Conference paper (Other academic)
  • 309.
    Hemmendorff, M.
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Andersson, Mats
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Kronander, T.
    SECTRA, Teknikringen 2, SE-583 30 Linköping, Sweden.
    Motion compensated digital subtraction angiography1999Conference paper (Refereed)
    Abstract [en]

    Digital subtraction angiography, whether based on traditional X-ray or MR, suers from patient motion artifacts. Until now, the usual remedy is to pixel shift by hand, or in some cases performing a global pixel shift semi-automatically. This is time consuming, and cannot handle rotations or local varying deformations over the image. We have developed a fully automatic algorithm that provides for motion compensation in the presence of large local deformations. Our motion compensation is very accurate for ordinary motions, including large rotations and deformations. It does not matter if the motions are irregular over time. For most images, it takes about a second per image to get adequate accuracy. The method is based on using the phase from lter banks of quadrature lters tuned in dierent directions and frequencies. Unlike traditional methods for optical ow and correlation, our method is more accurate and less susceptible to disturbing changes in the image, e.g. a moving contrast bolus. The implications for common practice are that radiologists' time can be significantly reduced in ordinary peripheral angiographies and that the number of retakes due to large or local motion artifacts will be much reduced.

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    Motion compensated digital subtraction angiography
  • 310.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Institute for Medical and Analytical Technologies, University of Applied Sciences and Art Northwestern Switzerland, Basel.
    Patient-specific electric field simulations and acceleration measurements for intraoperative test-stimulations2014Conference paper (Other academic)
  • 311.
    Hemm-Ode, Simone
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland.
    Pison, Daniela
    Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland.
    Alonso, Fabiola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Shah, Ashesh
    Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland.
    Coste, Jérôme
    Université Clermont Auvergne, Université d’Auvergne, EA 7282, Image Guided Clinical Neurosciences and Connectomics (IGCNC), Clermont-Ferrand, France; Service de Neurochirurgie, Hôpital Gabriel-Montpied, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France.
    Lemaire, Jean-Jacques
    Université Clermont Auvergne, Université d’Auvergne, EA 7282, Image Guided Clinical Neurosciences and Connectomics (IGCNC), Clermont-Ferrand, France; Service de Neurochirurgie, Hôpital Gabriel-Montpied, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Patient-Specific Electric Field Simulations and Acceleration Measurements for Objective Analysis of Intraoperative Stimulation Tests in the Thalamus2016In: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 10, p. 1-14, article id 577Article in journal (Refereed)
    Abstract [en]

    Despite an increasing use of deep brain stimulation (DBS) the fundamental mechanisms of action remain largely unknown. Simulation of electric entities has previously been proposed for chronic DBS combined with subjective symptom evaluations, but not for intraoperative stimulation tests. The present paper introduces a method for an objective exploitation of intraoperative stimulation test data to identify the optimal implant position of the chronic DBS lead by relating the electric field (EF) simulations to the patient-specific anatomy and the clinical effects quantified by accelerometry. To illustrate the feasibility of this approach, it was applied to five patients with essential tremor bilaterally implanted in the ventral intermediate nucleus (VIM). The VIM and its neighborhood structures were preoperatively outlined in 3D on white matter attenuated inversion recovery MR images. Quantitative intraoperative clinical assessments were performed using accelerometry. EF simulations (n = 272) for intraoperative stimulation test data performed along two trajectories per side were set-up using the finite element method for 143 stimulation test positions. The resulting EF isosurface of 0.2 V/mm was superimposed to the outlined anatomical structures. The percentage of volume of each structure’s overlap was calculated and related to the corresponding clinical improvement. The proposed concept has been successfully applied to the five patients. For higher clinical improvements, not only the VIM but as well other neighboring structures were covered by the EF isosurfaces. The percentage of the volumes of the VIM, of the nucleus intermediate lateral of the thalamus and the prelemniscal radiations within the prerubral field of Forel increased for clinical improvements higher than 50% compared to improvements lower than 50%. The presented new concept allows a detailed and objective analysis of a high amount of intraoperative data to identify the optimal stimulation target. First results indicate agreement with published data hypothesizing that the stimulation of other structures than the VIM might be responsible for good clinical effects in essential tremor. (Clinical trial reference number: Ref: 2011-A00774-37/AU905)

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  • 312.
    Hemm-Ode, Simone
    et al.
    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.
    Correlation between laser Doppler measurements and anatomy during deep brain stimulation surgery2012In: Biomedical Engineering, ISSN 0006-3398, E-ISSN 1573-8256, Vol. 57Article in journal (Refereed)
    Abstract [en]

    Introduction

    In Deep Brain Stimulation (DBS) the save, accurate and precise electrode implantation is essential. We have previously presented an optical technique for intra-operative measurements during DBS implantation. The aim of the present study was to establish the link between anatomy and total light intensity (TLI, the greyness of the tissue) and microvascular perfusion recordings.

    Methods

    Twelve patients (6 subthalamic nucleus STN, 6 ventral intermediate nucleus Vim) referred for unilateral or bilateral DBS-implantation for the treatment of essential tremor or Parkinson’s disease were included in the study. Stereotactic CT imaging was used for planning of the trajectories and targets (n=22). Measurement of the TLI and the microvascular perfusion were performed in mm-steps along the trajectory. TLI and perfusion data were post-processed to “optical trajectories” ranging from the cortex towards the target. These were compared with anatomy along the final trajectories by the use of a brain atlas and Surgiplan.

    Results

    Post-processing of the TLI signal showed a clear relationship with anatomy. Characteristic median curves were determined. The curve normally started with low values for STN and Vim patients when in cortex. When the probe entered white matter the TLI increased and stayed at this level until it passed in the vicinity to putamen, caudate nucleus or ventricle. A statistical significant difference (p<0.05) could be shown between white matter and putamen and between white matter and the target area. Concerning microvascular perfusion, high values were often seen in the cortex and low ones in white matter (significant statistical difference: p<0.05). In one case a small bleeding was suspected during surgery with the optical technique. This was confirmed with post-operative CT.

    Conclusion

    In summary the optical technique show promising results and typical trajectories were defined towards the STN and Vim, but further evaluation is necessary in order to refine the “optical bar codes” towards specific DBS-targets.

  • 313.
    Henzler, Philipp
    et al.
    Ulm University, Ulm, Germany.
    Rasche, Volker
    Ulm University, Ulm, Germany.
    Ropinski, Timo
    Ulm University, Ulm, Germany.
    Ritschel, Tobias
    University College London, London, United Kingdom.
    Single-image Tomography: 3D Volumes from 2D Cranial X-Rays2018In: Computer Graphics Forum (Proceedings of Eurographics 2018), Vol. 37, no 2, p. 377-388Article in journal (Refereed)
    Abstract [en]

    As many different 3D volumes could produce the same 2D x‐ray image, inverting this process is challenging. We show that recent deep learning‐based convolutional neural networks can solve this task. As the main challenge in learning is the sheer amount of data created when extending the 2D image into a 3D volume, we suggest firstly to learn a coarse, fixed‐resolution volume which is then fused in a second step with the input x‐ray into a high‐resolution volume. To train and validate our approach we introduce a new dataset that comprises of close to half a million computer‐simulated 2D x‐ray images of 3D volumes scanned from 175 mammalian species. Future applications of our approach include stereoscopic rendering of legacy x‐ray images, re‐rendering of x‐rays including changes of illumination, view pose or geometry. Our evaluation includes comparison to previous tomography work, previous learning methods using our data, a user study and application to a set of real x‐rays.

  • 314.
    Hernell, Frida
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, The Institute of Technology.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Smedby, Örjan
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Medical Radiology. Östergötlands Läns Landsting, Centre for Medical Imaging, Department of Radiology UHL. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    A blending technique for enhanced depth perception in medical x-ray vision applications2007In: Medicine Meets Virtual Reality 15 / [ed] James D. Westwood, Randy S. Haluck, Helene M. Hoffman, Greg T. Mogel, Roger Phillips, Richard A. Robb, Kirby G. Vosburgh, IOS Press, 2007, Vol. 125, p. 176-178Conference paper (Refereed)
    Abstract [en]

    Depth perception is a common problem for x-ray vision in augmented reality applications since the goal is to visualize occluded and embedded objects. In this paper we present an x-ray vision blending method for neurosurgical applications that intensifies the interposition depth cue in order to achieve enhanced depth perception. The proposed technique emphasizes important structures, which provides the user with an improved depth context.

  • 315.
    Hoefener, Henning
    et al.
    Fraunhofer MEVIS, Germany.
    Homeyer, Andre
    Fraunhofer MEVIS, Germany.
    Weiss, Nick
    Fraunhofer MEVIS, Germany.
    Molin, Jesper
    Sectra AB, Teknikringen 20, S-58330 Linkoping, Sweden.
    Lundström, Claes
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV). Sectra AB, Teknikringen 20, S-58330 Linkoping, Sweden.
    Hahn, Horst K.
    Fraunhofer MEVIS, Germany; Jacobs Univ, Germany.
    Deep learning nuclei detection: A simple approach can deliver state-of-the-art results2018In: Computerized Medical Imaging and Graphics, ISSN 0895-6111, E-ISSN 1879-0771, Vol. 70, p. 43-52Article in journal (Refereed)
    Abstract [en]

    Background: Deep convolutional neural networks have become a widespread tool for the detection of nuclei in histopathology images. Many implementations share a basic approach that includes generation of an intermediate map indicating the presence of a nucleus center, which we refer to as PMap. Nevertheless, these implementations often still differ in several parameters, resulting in different detection qualities. Methods: We identified several essential parameters and configured the basic PMap approach using combinations of them. We thoroughly evaluated and compared various configurations on multiple datasets with respect to detection quality, efficiency and training effort. Results: Post-processing of the PMap was found to have the largest impact on detection quality. Also, two different network architectures were identified that improve either detection quality or runtime performance. The best-performing configuration yields f1-measures of 0.816 on Hamp;E stained images of colorectal adenocarcinomas and 0.819 on Ki-67 stained images of breast tumor tissue. On average, it was fully trained in less than 15,000 iterations and processed 4.15 megapixels per second at prediction time. Conclusions: The basic PMap approach is greatly affected by certain parameters. Our evaluation provides guidance on their impact and best settings. When configured properly, this simple and efficient approach can yield equal detection quality as more complex and time-consuming state-of-the-art approaches. (C) 2018 The Authors. Published by Elsevier Ltd.

  • 316.
    Holmberg, L. Joakim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Mechanics.
    Lund Ohlsson, Marie
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Mechanics.
    Danvind, Jonas
    Mittuniversitetet.
    Can Simulations Assist in Classification Development?2013In: Equipment and Technology in Paralympic Sports, International Paralympic Committee , 2013Conference paper (Other academic)
    Abstract [en]

    There is a critical need for research that describes the extent to which impairments of varying type, severity and distribution impact performance in Paralympic sports. It is important with evidence-based judgment on how the impairments aect performance. In the following, we present a complementary evidence-based tool for classication.

    Let us start with an example. We recently presented a study (Holmberg et al., 2012)1 that utilized two full-body musculoskeletal simulation models of cross-country skiing (double-poling). The models were identical except that one carried no muscles in the right lower leg and foot; thus mimicking a lower leg prosthesis. It was hypothesized that a lower leg prosthesis would inuence muscular work throughout the whole body. Results showed that to generate the same motion and external work, an able-bodied skier only had to produce about 80% metabolic muscle work compared to a disabled skier (with a non-active right lower leg prosthesis).

    In reality there is always psychological factors present and it is probably not possible to nd two human beings (one fully functional and one impaired) with the same tness, size, strength and technique. Thus, it is hard to nd the unbiased eect of an impairment on performance in a speci c sport. The example above shows the strength of using simulations because a  musculoskeletal model yields quantitative data on the unbiased eect of dierent functional impairments.

    In cross-country skiing, athletes with functional impairments are, in 'competition format' classification, assigned to dierent categories with weight factors. Athletes perform their race and the result list is presented as race time multiplied by weight factor. In the future, musculoskeletal simulations may assist in answering how a specic functional impairment aects performance and thereby improve the fairness in assigning weight factors for classication.

    Download (pdf)
    Presentation: Can Simulations Assist in Classification Development?
  • 317.
    Hope, Michael D.
    et al.
    University of California, San Francisco, USA.
    Dyverfeldt, Petter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping. University of California, San Francisco, USA.
    Thoracic Aorta Disease: Flow Evaluation by MR2013In: MRI and CT of the Cardiovascular System / [ed] Charles B Higgins; Albert de Roos, Philadelphia, PA: Lippincott Williams & Wilkins, 2013, 3, p. -676Chapter in book (Other academic)
    Abstract [en]

    Leave no disease undetected with MRI and CT of the Cardiovascular System, your definitive guide to magnetic resonance and computed tomography for cardiovascular health. Authored by a collaboration of international experts, this vivid, four-color third edition imparts the latest technologies in a rapidly advancing field. With topics that range from anatomy, to MR in infants and children, to risk assessment in ischemic heart disease  this text includes seven new chapters to reflect the rising tide of technological discovery as it pertains to cardiology.  Thanks to its expert analysis, procedural guide to implementation, and profound understanding of the recent advances in cardiovascular imagining, MRI and CT of the Cardiovascular System gives you all the tools necessary for powerful screening, diagnosis, and  cardiovascular care. Features:

    --New chapters reflecting  technological discoveries in cardiology  --Color illustrations for heightened clarity --Companion website with fully searchable text --Units organized by pathology and disease detection --Fully updated information on application of MR and CT--Up-to-date analysis of emerging multi-detector CT

  • 318.
    Hope, Michael D.
    et al.
    University of California, San Francisco, USA.
    Dyverfeldt, Petter
    University of California, San Francisco, USA.
    Acevedo-Bolton, Gabriel
    University of California, San Francisco, USA.
    Wrenn, Jarrett
    University of California, San Francisco, USA.
    Foster, Elyse
    University of California, San Francisco, USA.
    Tseng, Elaine
    University of California, San Francisco, USA.
    Saloner, David
    University of California, San Francisco, USA.
    Post-stenotic dilation: evaluation of ascending aortic dilation with 4D flow MR imaging2012In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 156, no 2, p. e40-e42Article in journal (Other academic)
  • 319.
    Hope, Michael D.
    et al.
    University of California, San Francisco, USA.
    Sedlic, Tony
    University of California, San Francisco, USA.
    Dyverfeldt, Petter
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. University of California, San Francisco, USA.
    Cardiothoracic Magnetic Resonance Flow Imaging2013In: Journal of thoracic imaging, ISSN 0883-5993, E-ISSN 1536-0237, Vol. 28, no 4, p. 217-230Article in journal (Refereed)
    Abstract [en]

    Multidimensional blood flow imaging with magnetic resonance has rapidly evolved over the last decade. The technique, often referred to as 4-dimensional (4D) flow, can now reliably image the heart and principal vessels of the chest in ≤15 minutes. In addition to dynamic 3D flow visualization, a range of unique quantitative hemodynamic markers can be calculated from 4D flow data. In this review article, we describe some of the more promising of these hemodynamic markers, including pulse wave velocity, pressure, turbulent kinetic energy, wall shear stress, and flow eccentricity. Evaluation of a range of cardiothoracic disorders has been explored with 4D flow, and many applications have been proposed. We also review the potential clinical applications of 4D flow in 4 broad contexts: the aorta, the pulmonary artery, acquired heart disease, and complex congenital heart disease. Promising preliminary results will be highlighted, including the use of abnormal systolic blood flow to risk-stratify patients for progressive valve-related aortic disease, turbulent kinetic energy to directly assess the hemodynamic impact of a stenotic lesion, and altered intracardiac flow to identify early heart failure. We discuss ongoing research efforts in the context of the larger clinical goals of 4D flow: the use of unique hemodynamic markers to (1) identify cardiovascular disease processes early in their course before clinical manifestation so that preemptive treatment can be undertaken; (2) refine the assessment of cardiovascular disease so as to better identify optimal medical or surgical therapies; and (3) enhance the evaluation and monitoring of the hemodynamic impact of different treatment options.

  • 320.
    Hope, Michael D.
    et al.
    University of California, San Francisco, USA.
    Wrenn, S. Jarrett
    University of California, San Francisco, USA.
    Dyverfeldt, Petter
    University of California, San Francisco, USA.
    Clinical Applications of Aortic 4D Flow Imaging2013In: Current Cardiovascular Imaging Reports, ISSN 1941-9066, Vol. 6, no 2, p. 128-139Article in journal (Refereed)
    Abstract [en]

    Quantitative aortic magnetic resonance (MR) blood flow imaging is a rapidly advancing technique that is likely to impact clinical medicine in the near future. The acquisition of comprehensive 4D velocity datasets is now possible in a clinically acceptable time frame. Unique and intuitive visualization methods are available. A number of important hemodynamic biomarkers can be derived from the data, and exploited to help understand how abnormal flow is inter-related with aortic pathology. Initial data suggest that some of the derived biomarkers can refine the clinical assessment of aortic disease and predict disease progression. We provide an overview of aortic imaging with emphasis on how flow imaging is currently used, discuss the fundamental technical aspects of multidimensional MR flow imaging, introduce key hemodynamic markers, and show how this type of imaging may soon be used for the early identification of patients at risk for the development of potentially devastating aortic complications.

  • 321.
    Hult, Peter
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Science & Engineering.
    NovaMedTech2009Conference paper (Other academic)
  • 322.
    Hult, Peter
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    NovaMedTech – Innovationer för morgondagens vård genom samverkan med vård, akademi och industri2010Conference paper (Other (popular science, discussion, etc.))
    Abstract [sv]

    Med en kraftig ökning av andelen äldre i befolkningen ställs allt större krav på sjukvården. Ny medicinsk teknik utgör en möjlig väg att göra vården effektivare. Utgående från detta är NovaMedTech en innovativ miljö som stöds av EUs Strukturfond och som skall bidra till att stärka ny utveckling av medicinsk teknik inom regionen Östra Mellansverige dvs de fyra länen Sörmland, Västmanland, Örebro och Östergötland. I programmet tas ett samlat grepp genom att vård, akademi och industri samverkar mellan de olika länen. Satsningen stärks av länens kompletterande styrkor.

    NovaMedTech satsar genom ekonomiskt stöd från EU-strukturfondsprogram via Tillväxtverket på de två olika produktområden: Medicinsk teknik för distribuerad vård och personlig hälsa och Medicinsk teknik för bildbaserad diagnostik och terapi. Vi stöder ett 30-tal konkreta projekt mot klinisk testning och kommersialisering av produkter och tjänster.

    Genom NovaMedTech utvecklas även en innovativ miljö där ett brett nätverk har skapats och där dess aktörer har givits möjlighet att samverka, utbyta erfarenheter, identifiera nya idéer mm. Viktiga framgångsfaktorer för NovaMedTech har varit en god regional förankring, en mångfald av aktörer inom vård, akademi och näringsliv, att satsningen bygger på redan befintliga utvecklingsstrukturer i form av nätverk, innovationsstöd, inkubatorverksamhet, nyföretagarstöd, såddfinansiering, hälsoekonomisk analys och entreprenörskapssatsningar mm, samt att NovaMedTech har en stark koppling till näringslivet.

    Produktområdet Medicinsk teknik för distribuerad vård och personlig hälsa handlar om teknik för fysiologisk övervakning av patienter i hemmiljö samt teknik för diagnostik inom närvård/primärvård. I framtiden bör patientinformation och mätdata överföras istället för att patienter transporteras. Lösningar kan innefatta teknik för ”point of care”-diagnostik inom närvård/primärvård. Med medicinsk teknik för personlig hälsa avser vi monitorering av patienter med risk för att utveckla en viss sjukdom eller som har en kronisk sjukdom. Bland delprojekt som vi arbetar med kan nämnas: Tekniska metoder för att patienter kan bo kvar i sin hemmiljö, Informationsteknik för att underlätta patientens vardagsbestyr, Mät- och kommunikationsplattformar för fysiologiska signaler/labprover, Trådlös informationsöverföring, Journalsystem för distribuerad vård samt Monitorering/övervakning av fysiologiska parameter kopplade till kroniska sjudomar

    Medicinsk teknik för bildbaserad diagnostik och terapi blir allt viktigare i en högteknologisk sjukvård. Vi arbetar med att vidareutveckla tekniken framför allt genom att på nya sätt processa bildinformationen. Exempel på delprojket som vi driver är: Avbildning av vävnad med hjälp av mikrovågstomografi, Utveckling av ny MR-teknik för hjärtundersökning, Avancerad bildbehandling av datortomografibilder och mikroskopbilder och Medicinska bilder för att simulera och styra behandling.

    Projektet har pågått i ca 2 år och bland hittills uppnådda resultat kan nämnas ca 60 identifierade produktidéer, att 20 produktidéer har tagits till klinisk evaluering, att 9 prototyper har kommit till en kommersialiseringsfas och att 3 nya företag hittills har bildats genom NovaMedTechs medverkan.

  • 323.
    Hult, Peter
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Science & Engineering.
    NovaMedTech. Nya Medicintekniska Produkter och tjänster för Morgondagens Vård och Omsorg.2008Conference paper (Other academic)
  • 324.
    Hult, Peter
    et al.
    Linköping University, Department of Biomedical Engineering.
    Alod, Tanja
    Linköping University, Department of Biomedical Engineering.
    Rattfält, Linda
    Linköping University, Department of Biomedical Engineering.
    Textile electrodes - An alternative as ECG electrodes in home health care?2006Conference paper (Other academic)
    Abstract [en]

    The use of electrocardiogram (ECG) is a well known and widely used method. However, when the home health care is expanding, new demands for ECG equipment is seen. It would be desirable if electrodes would be more comfortable to use, especially for long-time registrations. The contact between electrodes and skin becomes worse with time and electrodes can also irritate the skin. With textile technology of today, yarns can be created with leading materials [1]. Thin threads of metal are spun into yarn and can be used for weaving or knitting fabrics. These fabrics can be used as electrodes for ECG registration, with the advantage of textile properties. By integrating such electrodes in clothes, the electrodes could become more wearable and more suitable for some ECG registrations [2, 3, 4] . The difficulty of distinguishing QRS-complexes will be used for studying signals from textile electrodes. In this study, three different textile sensors was compared in order to investigate influences in the ECG signal caused by material, size or structure. Such influences could contaminate the signal with different types of noise and make it difficult to distinguish the characteristics of the ECG [5].

  • 325.
    Hult, Peter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Fjällbrant, T
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Detection of the third heart sound using a tailored wavelet approach.2004In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 42, no 2, p. 253-258Article in journal (Refereed)
    Abstract [en]

    The third heart sound is normally heard during auscultation of younger individuals but disappears with increasing age. However, this sound can appear in patients with heart failure and is thus of potential diagnostic use in these patients. Auscultation of the heart involves a high degree of subjectivity. Furthermore, the third heart sound has low amplitude and a low-frequency content compared with the first and second heart sounds, which makes it difficult for the human ear to detect this sound. It is our belief that it would be of great help to the physician to receive computer-based support through an intelligent stethoscope, to determine whether a third heart sound is present or not. A precise, accurate and low-cost instrument of this kind would potentially provide objective means for the detection of early heart failure, and could even be used in primary health care. In the first step, phonocardiograms from ten children, all known to have a third heart sound, were analysed, to provide knowledge about the sound features without interference from pathological sounds. Using this knowledge, a tailored wavelet analysis procedure was developed to identify the third heart sound automatically, a technique that was shown to be superior to Fourier transform techniques. In the second step, the method was applied to phonocardiograms from heart patients known to have heart failure. The features of the third heart sound in children and of that in patients were shown to be similar. This resulted in a method for the automatic detection of third heart sounds. The method was able to detect third heart sounds effectively (90%), with a low false detection rate (3.7%), which supports its clinical use. The detection rate was almost equal in both the children and patient groups. The method is therefore capable of detecting, not only distinct and clearly visible/audible third heart sounds found in children, but also third heart sounds in phonocardiograms from patients suffering from heart failure.

  • 326.
    Hult, Peter
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Science & Engineering.
    Lindén, Maria
    Mälardalens högskola.
    Distribuerad vård – Möjligheter, behov och svårigheter - En diskussion om den framtida vården.2007Conference paper (Other academic)
  • 327.
    Hult, Peter
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Lindén, Maria
    Institutionen för datavetenskap och elektronik, Mälardalens högskola, Västerås, Sverige.
    Rattfält, Linda
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Distribuerad vård - Möjligheter, Behov och svårigheter.2006Conference paper (Other academic)
  • 328.
    Hult, Peter
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, Faculty of Arts and Sciences.
    Wranne, Bengt
    Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    A bioacoustic method for timing of the different phases of the breathing cycle and monitoring of breathing frequency.2000In: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 22, no 6, p. 425-433Article in journal (Refereed)
    Abstract [en]

    It is well known that the flow of air through the trachea during respiration causes vibrations in the tissue near the trachea, which propagate to the surface of the body and can be picked up by a microphone placed on the throat over the trachea. Since the vibrations are a direct result of the airflow, accurate timing of inspiration and expiration is possible. This paper presents a signal analysis solution for automated monitoring of breathing and calculation of the breathing frequency. The signal analysis approach uses tracheal sound variables in the time and frequency domains, as well as the characteristics of the disturbances that can be used to discriminate tracheal sound from noise. One problem associated with the bioacoustic method is its sensitivity for acoustic disturbances, because the microphone tends to pick up all vibrations, independent of their origin. A signal processing method was developed that makes the bioacoustic method clinically useful in a broad variety of situations, for example in intensive care and during certain heart examinations, where information about both the precise timing and the phases of breathing is crucial.

  • 329.
    Hultman, Martin
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Fredriksson, Ingemar
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Perimed AB, Järfälla-Stockholm, Sweden.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Alvandpour, Atila
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    A 15.6 frames per second 1 megapixel Multiple Exposure Laser Speckle Contrast Imaging setup2018In: Journal of Biophotonics, ISSN 1864-063X, E-ISSN 1864-0648, Vol. 11, no 2, article id e201700069Article in journal (Refereed)
    Abstract [en]

    A multiple exposure laser speckle contrast imaging (MELSCI) setup for visualizing blood perfusion was developed using a field programmable gate array (FPGA), connected to a 1000 frames per second (fps) 1-megapixel camera sensor. Multiple exposure time images at 1, 2, 4, 8, 16, 32 and 64 milliseconds were calculated by cumulative summation of 64 consecutive snapshot images. The local contrast was calculated for all exposure times using regions of 4 × 4 pixels. Averaging of multiple contrast images from the 64-millisecond acquisition was done to improve the signal-to-noise ratio. The results show that with an effective implementation of the algorithm on an FPGA, contrast images at all exposure times can be calculated in only 28 milliseconds. The algorithm was applied to data recorded during a 5 minutes finger occlusion. Expected contrast changes were found during occlusion and the following hyperemia in the occluded finger, while unprovoked fingers showed constant contrast during the experiment. The developed setup is capable of massive data processing on an FPGA that enables processing of MELSCI data in 15.6 fps (1000/64 milliseconds). It also leads to improved frame rates, enhanced image quality and enables the calculation of improved microcirculatory perfusion estimates compared to single exposure time systems.

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  • 330.
    Hultman, Martin
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Fredriksson, Ingemar
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Perimed AB, Järfälla-Stockholm, Sweden.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Evaluation of a high framerate multi-exposure laser speckle contrast imaging setup2018In: High-Speed Biomedical Imaging and Spectroscopy III: Toward Big Data Instrumentation and Management / [ed] Kevin K. Tsia, Keisuke Goda, SPIE - International Society for Optical Engineering, 2018Conference paper (Refereed)
    Abstract [en]

    We present a first evaluation of a new multi-exposure laser speckle contrast imaging (MELSCI) system for assessing spatial variations in the microcirculatory perfusion. The MELSCI system is based on a 1000 frames per second 1-megapixel camera connected to a field programmable gate arrays (FPGA) capable of producing MELSCI data in realtime. The imaging system is evaluated against a single point laser Doppler flowmetry (LDF) system during occlusionrelease provocations of the arm in five subjects. Perfusion is calculated from MELSCI data using current state-of-the-art inverse models. The analysis displayed a good agreement between measured and modeled data, with an average error below 6%. This strongly indicates that the applied model is capable of accurately describing the MELSCI data and that the acquired data is of high quality. Comparing readings from the occlusion-release provocation showed that the MELSCI perfusion was significantly correlated (R=0.83) to the single point LDF perfusion, clearly outperforming perfusion estimations based on a single exposure time. We conclude that the MELSCI system provides blood flow images of enhanced quality, taking us one step closer to a system that accurately can monitor dynamic changes in skin perfusion over a large area in real-time

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  • 331. Order onlineBuy this publication >>
    Häggblad, Erik
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    In Vivo Diffuse Reflectance Spectroscopy of Human Tissue: From Point Measurements to Imaging2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents the non-invasive use of diffuse reflectance spectroscopy (DRS) to provide information about the biochemical composition of living tissue. During DRS measurements, the incident, visible light is partially absorbed by chromophores but also scattered in the tissue before being remitted.

    Human skin and heart, the main tissue objects in this thesis, are dependent on a sufficient inflow of oxygenized blood, and outflow of metabolic byproducts. This process could be monitored by DRS using the spectral fingerprints of the most important tissue chromophores, oxyhemoglobin and deoxyhemoglobin.

    The Beer-Lambert law was used to produce models for the DRS and has thus been a foundation for the analyses throughout this work. Decomposition into the different chromophores was performed using least square fitting and tabulated data for chromophore absorptivity.

    These techniques were used to study skin tissue erythema induced by a provocation of an applied heat load on EMLA-treated skin. The absorbance differences, attributed to changes in the hemoglobin concentrations, were examined and found to be related to, foremost, an increase in oxyhemoglobin.

    To estimate UV-induced border zones between provoked and nonprovoked tissue a modified Beer-Lambert model, approximating the scattering effects, was used. An increase of chromophore content of more than two standard deviations above mean indicated responsive tissue. The analysis revealed an edge with a rather diffuse border, contradictory to the irradiation pattern.

    Measuring in the operating theater, on the heart, it was necessary to calculate absolute chromophore values in order to assess the state of the myocardium. Therefore, a light transport model accounting for the optical properties, and a calibrated probe, was adopted and used. The absolute values and fractions of the chromophores could then be compared between sites and individuals, despite any difference of the optical properties in the tissue.

    A hyperspectral imaging system was developed to visualize the spatial distribution of chromophores related to UV-provocations. A modified Beer-Lambert approximation was used including the chromophores and a baseline as an approximate scattering effect. The increase in chromophore content was estimated and evaluated over 336 hours.

    In conclusion, advancing from a restricted Beer-Lambert model, into a model estimating the tissue optical properties, chromophore estimation algorithms have been refined progressively. This has allowed advancement from relative chromophore analysis to absolute values, enabling precise comparisons and good prediction of physiological conditions.

    List of papers
    1. Reflection Spectroscopy of Analgesized Skin
    Open this publication in new window or tab >>Reflection Spectroscopy of Analgesized Skin
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    2001 (English)In: Microvascular Research, ISSN 0026-2862, E-ISSN 1095-9319, Vol. 62, no 3, p. 392-400 Article in journal (Refereed) Published
    Abstract [en]

    Analgesized skin, when subjected to heat stimuli, responds by increasing skin perfusion. This response does not originate from increased perfusion in superficial capillaries, but rather in the deeper lying vessels. The aim of this study was to assess changes in blood chromophore content, measured by reflection spectroscopy, in relation to the perfusion increase, especially regarding the chromophores oxyhemoglobin and deoxyhemoglobin. Eleven normal subjects were treated with analgesic cream (EMLA) and placebo for 20, 40, 60, 120, and 180 min. Individual reactions to local heating were classified as responses if the change in reflection data or the change in perfusion, as measured by laser Doppler blood flowmetry, exceeded 2 standard deviations of normal variation. The increase in blood perfusion or in blood content gave rise to an increased absorption, interpreted as an increase due mainly to the chromophore oxyhemoglobin. The number of responses increased with increased treatment time for EMLA-treated areas. In general, there was a good agreement between both methods; 44 of 55 classifications coincided for the two methods used. In conclusion, analgesized forearm skin, which had been exposed to local heating, responded with an elevated perfusion consisting of oxygenated blood. This strengthens the hypothesis that the flow increase occurs through dilatation of larger deeper lying skin vessels and not in the capillaries.

    Place, publisher, year, edition, pages
    ScienceDirect, 2001
    Keywords
    spectroscopy; laser Doppler flowmetry; EMLA; hemoglobin; analgesia; heat stimuli; skin microcirculation
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-15184 (URN)10.1006/mvre.2001.2358 (DOI)
    Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2017-12-14Bibliographically approved
    2. A diffuse reflectance spectroscopic study of UV-induced erythematous reaction across well-defined borders in human skin
    Open this publication in new window or tab >>A diffuse reflectance spectroscopic study of UV-induced erythematous reaction across well-defined borders in human skin
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    2010 (English)In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 16, no 3, p. 283-290Article in journal (Refereed) Published
    Abstract [en]

    Introduction The colour of tissue is often of clinicaluse in the diagnosis of tissue homeostasis andphysiological responses to various stimuli.Determining tissue colour changes and borders,however, often poses an intricate problem and visualexamination, constituting clinical praxis, does notallow them to be objectively characterized orquantified. Demands for increased inter- and intraobserverreproducibility have been incentives for theintroduction of objective methods and techniques fortissue colour (e.g. erythema) evaluation. The aim ofthe present paper was to study the border zone of anUVB provoked erythematous response of humanskin in terms of blood volume and oxygenationmeasured by means of diffuse reflectancespectroscopy using a commercial probe.

    Material and Methods A provocation model, basedon partial masking of irradiated skin areas, definestwo erythema edges at every skin site responding tothe UV irradiation. In every subject, 5 test sites wereexposed with a constant UV light irradiance (14mW/cm2), but with different exposures times (0, 3,6, 9, 12 seconds). An analysis of the spectral datameasured across the two edges was performed for every scan line. The oxygenized and deoxygenizedhemoglobin contents were estimated in everymeasurement point, using a modified Beer-Lambertmodel.

    Results The fit of the experimental data to the model derived by the modified Beer-Lambert law was excellent (R2>0.95). Analyzing data for the chromophore content showed that the erythematous response in provoked areas is dominated by the increase in oxyhemoglobin. The width for the left and right border zone was estimated to 1.81±0.93 mm and 1.90±0.88 mm respectively (M±SD). The unprovoked area between the two edges was estimated to 0.77±0.68 mm.

    Conclusion While the chosen data analysis performed satisfactory, the ability of the probe design to differentiate spatial aspects of a reaction with abrupt borders was found to be suboptimal resulting in a probable overestimation of the erythematous edge slope. Probe modification or imaging are possible solutions.

    Place, publisher, year, edition, pages
    Wiley, 2010
    Keywords
    Erythema, UV, Spectroscopy, Oxygenation, Human skin
    National Category
    Biomedical Laboratory Science/Technology
    Identifiers
    urn:nbn:se:liu:diva-15185 (URN)10.1111/j.1600-0846.2010.00424.x (DOI)
    Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2017-12-14Bibliographically approved
    3. Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting
    Open this publication in new window or tab >>Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting
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    2008 (English)In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 13, no 5, p. 054030-Article in journal (Refereed) Published
    Abstract [en]

    We present a study using a method able to assess tissue oxygenation, taking into account the absorption and the level of scattering in myocardial tissue using a calibrated fiber optic probe. With this method, interindividual comparisons of oxygenation can be made despite varying tissue optical properties during coronary artery bypass grafting (CABG). During CABG, there are needs for methods allowing continuous monitoring and prediction of the metabolism in the myocardial tissue. 14 patients undergoing CABG are investigated for tissue oxygenation during different surgical phases using a handheld fiber optic spectroscopic probe with a source-detector distance of less than 1 mm. The probe is calibrated using a light transport model, relating the absorption and reduced scattering coefficients (mu(a) and mu()(s)) to the measured spectra. By solving the inverse problem, absolute measures of tissue oxygenation are evaluated by the sum of oxygenized hemoglobin and myoglobin. Agreement between the model and measurements is obtained with an average correlation coefficient R-2 of 0.96. Oxygenation is found to be significantly elevated after aorta cross-clamping and cardioplegic infusion, as well as after reperfusion, compared to a baseline (p < 0.05). Tissue oxygenation decreases during cardiac arrest and increases after reperfusion.

    Keywords
    diffuse reflectance spectroscopy, oxygenation, myocardium, tissue, coronary artery bypass grafting
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-16251 (URN)10.1117/1.2976433 (DOI)
    Note

    Original Publication: Erik Häggblad, Tobias Lindbergh, Daniel Karlsson, Henrik Casimir-Ahn, Göran Salerud and Tomas Strömberg, Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting, Journal of Biomedical Optics, (13), 5, 054030, 2008. http://dx.doi.org/10.1117/1.2976433 Copyright 2008 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

    Available from: 2009-01-12 Created: 2009-01-09 Last updated: 2017-05-23Bibliographically approved
    4. Visible, Hyperspectral Imaging Evaluating the Cutaneous Response to Ultraviolet Radiation
    Open this publication in new window or tab >>Visible, Hyperspectral Imaging Evaluating the Cutaneous Response to Ultraviolet Radiation
    2007 (English)In: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V / [ed] Daniel L. Farkas; Robert C. Leif; Dan V. Nicolau, SPIE - International Society for Optical Engineering, 2007, p. 644103-1-644103-12Conference paper, Published paper (Other academic)
    Abstract [en]

    In vivo diagnostics of skin diseases as well as understanding of the skin biology constitute a field demanding characterization of physiological and anatomical parameters. Biomedical optics has been successfully used, to qualitatively and quantitatively estimate the microcirculatory conditions of superficial skin. Capillaroscopy, laser Doppler techniques and spectroscopy, all elucidate different aspects of microcirculation, e.g. capillary anatomy and distribution, tissue perfusion and hemoglobin oxygenation. We demonstrate the use of a diffuse reflectance hyperspectral imaging system for spatial and temporal characterization of tissue oxygenation, important to skin viability. The system comprises: light source, liquid crystal tunable filter, camera objective, CCD camera, and the decomposition of the spectral signature into relative amounts of oxy- and deoxygenized hemoglobin as well as melanin in every pixel resulting in tissue chromophore images. To validate the system, we used a phototesting model, creating a graded inflammatory response of a known geometry, in order to evaluate the ability to register spatially resolved reflectance spectra. The obtained results demonstrate the possibility to describe the UV inflammatory response by calculating the change in tissue oxygen level, intimately connected to a tissue's metabolism. Preliminary results on the estimation of melanin content are also presented.

    Place, publisher, year, edition, pages
    SPIE - International Society for Optical Engineering, 2007
    Series
    Proceedings of SPIE (Progress in biomedical optics and imaging), ISSN 1605-7422 ; 6441
    Keywords
    Hyperspectral imaging, Ultraviolet provocation, Erythema, Hemoglobin, CCD camera, Tunable filters
    National Category
    Medical Laboratory and Measurements Technologies
    Identifiers
    urn:nbn:se:liu:diva-15190 (URN)10.1117/12.698165 (DOI)000245855200002 ()9780819465542 (ISBN)
    Conference
    Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V, 20 January 2007, San Jose, CA, USA
    Available from: 2008-10-22 Created: 2008-10-22 Last updated: 2014-01-30Bibliographically approved
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  • 332.
    Härd, Victoria
    Linköping University, Department of Electrical Engineering, Computer Vision.
    Automatic Alignment of 2D Cine Morphological Images Using 4D Flow MRI Data2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cardiovascular diseases are among the most common causes of death worldwide. One of the recently developed flow analysis technique called 4D flow magnetic resonance imaging (MRI) allows an early detection of such diseases. Due to the limited resolution and contrast between blood pool and myocardium of 4D flow images, cine MR images are often used for cardiac segmentation. The delineated structures are then transferred to the 4D Flow images for cardiovascular flow analysis. Cine MR images are however acquired with multiple breath-holds, which can be challenging for some people, especially, when a cardiovascular disease is present. Consequently, unexpected breathing motion by a patient may lead to misalignments between the acquired cine MR images.

    The goal of the thesis is to test the feasibility of an automatic image registration method to correct the misalignment caused by respiratory motion in morphological 2D cine MR images by using the 4D Flow MR as the reference image. As a registration method relies on a set of optimal parameters to provide desired results, a comprehensive investigation was performed to find such parameters. Different combinations of registration parameters settings were applied on 20 datasets from both healthy volunteers and patients. The best combinations, selected on the basis of normalized cross-correlation, were evaluated using the clinical gold-standard by employing widely used geometric measures of spatial correspondence. The accuracy of the best parameters from geometric evaluation was finally validated by using simulated misalignments.

    Using a registration method consisting of only translation improved the results for both datasets from healthy volunteers and patients and the simulated misalignment data. For the datasets from healthy volunteers and patients, the registration improved the results from 0.7074 ± 0.1644 to 0.7551 ± 0.0737 in Dice index and from 1.8818 ± 0.9269 to 1.5953 ± 0.5192 for point-to-curve error. These values are a mean value for all the 20 datasets.

    The results from geometric evaluation on the data from both healthy volunteers and patients show that the developed correction method is able to improve the alignment of the cine MR images. This allows a reliable segmentation of 4D flow MR images for cardiac flow assessment.

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  • 333.
    Hård af Segerstad, Helene
    et al.
    Linköping University, Department of Behavioural Sciences and Learning. Linköping University, Faculty of Educational Sciences.
    Setterud, Helen
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Arts and Sciences.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    An alternative supervision model of Master thesis2008Conference paper (Other academic)
  • 334.
    Hård af Segerstad, Helene
    et al.
    Linköping University, Department of Behavioural Sciences and Learning. Linköping University, Faculty of Educational Sciences.
    Setterud, Helen
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Arts and Sciences.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Master students and supervisors’ conceptions and experiences of an alternative model of supervision2008Conference paper (Other academic)
  • 335.
    Högberg Mårder, Thérèse
    Linköping University, Department of Biomedical Engineering.
    Modelling breast cancer pathology reports using SNOMED CT and openEHR2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With a longer-living population and an increase in cancer incidence the health care’s workload has increased over the past decade. The treatment process of a cancer patient is dependant on clinical information collected and communicated from the pathology department. With a standardised and structured pathology report the information communicated can become easier to interpret and will fa- cilitate the search for important parameters.

    This master thesis aims to develop a template prototype to replace four static free-text templates used in the area of breast cancer pathology at the pathology department at Region Östergötland. The end product was intends to store docu- mented information in a structured manner through structured data, in order to obtain semantic interoperability.

    Semantic interoperability means that different systems are able to communicate with each other in such a way that the information is handled and interpreted equally by the systems. By using certain standards such as openEHR archetypes and SNOMED CT concepts, the data becomes uniform and unambiguous. When that is achieved, information can be sent more easily between systems such as patient health data if an individual moves between different cities where the hos- pitals have different medical records systems.

    The result of the master thesis is a single template that incorporates all the parts from the four static templates currently used at Region Östergötland. To avoid a large and cumbersome template for the end-user the template is built with con- ditions that changed the appearance of the template while it is being filled in, making it dynamic.

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    fulltext
  • 336.
    Ilias, Michail A.
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Häggblad, Erik
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Anderson, Chris
    Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology UHL.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Visible, Hyperspectral Imaging Evaluating the Cutaneous Response to Ultraviolet Radiation2007In: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues V / [ed] Daniel L. Farkas; Robert C. Leif; Dan V. Nicolau, SPIE - International Society for Optical Engineering, 2007, p. 644103-1-644103-12Conference paper (Other academic)
    Abstract [en]

    In vivo diagnostics of skin diseases as well as understanding of the skin biology constitute a field demanding characterization of physiological and anatomical parameters. Biomedical optics has been successfully used, to qualitatively and quantitatively estimate the microcirculatory conditions of superficial skin. Capillaroscopy, laser Doppler techniques and spectroscopy, all elucidate different aspects of microcirculation, e.g. capillary anatomy and distribution, tissue perfusion and hemoglobin oxygenation. We demonstrate the use of a diffuse reflectance hyperspectral imaging system for spatial and temporal characterization of tissue oxygenation, important to skin viability. The system comprises: light source, liquid crystal tunable filter, camera objective, CCD camera, and the decomposition of the spectral signature into relative amounts of oxy- and deoxygenized hemoglobin as well as melanin in every pixel resulting in tissue chromophore images. To validate the system, we used a phototesting model, creating a graded inflammatory response of a known geometry, in order to evaluate the ability to register spatially resolved reflectance spectra. The obtained results demonstrate the possibility to describe the UV inflammatory response by calculating the change in tissue oxygen level, intimately connected to a tissue's metabolism. Preliminary results on the estimation of melanin content are also presented.

  • 337.
    Ilias, Michail
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Stücker, M.
    Department of Dermatology, Ruhr University, Bochum, Germany.
    Anderson, Chris
    Linköping University, Department of Biomedicine and Surgery, Dermatology. Linköping University, Faculty of Health Sciences.
    Salerud, Göran
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Assessment of pigmented skin lesions in terms of blood perfusion estimates2004In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 10, no 1, p. 43-49Article in journal (Refereed)
    Abstract [en]

    Background/aims: Cutaneous malignant melanoma is a disease of increasing clinical and economical importance. The prognosis is good with early diagnosis. The chief differential diagnosis is benign melanocytic naevus, a common lesion in Caucasians. Attempts have been made to use bioengineering techniques to aid in the initial diagnosis. The present study proposes a method of extracting possibly discriminative blood perfusion properties in pigmented skin lesions by combining information on the lesions' blood perfusion with optical or visual information of their spatial extent.

    Methods: A total of 46 blood perfusion measurements were performed on 22 pigmented skin lesions, the ultimate diagnosis of which was three histologically proven malignant melanomas, four histologically proven benign naevi and fifteen naevi assessed by two specialist dermatologists as being benign. Laser Doppler perfusion imaging gave two different types of two-dimensional data sets (64×64 pixels), one representing the total backscattered light intensity at each measurement point (TLI image) and the second corresponding to perfusion values. The boundaries of each examined lesion were derived from the TLI image employing greyscale thresholding, thus resulting in an estimated region of interest (ROI) approximating the optical extent of the lesion. The ROI was superimposed on the perfusion image and extraction of perfusion features was then performed.

    Results: The processing of the TLI images was successful in delineating the lesions' boundaries. The first hypothesis that the mean perfusion quotients in MM and benign naevi are equal could not be rejected at the chosen 5% level of significance. The second hypothesis that the mean percent-age of elevated perfusion values (image pixels) within the ROI shows no difference between MM and benign naevi could be rejected at a 5% level of significance.

    Conclusions: This study has presented a method of extracting blood perfusion parameters of pigmented skin lesions by combining blood perfusion information with information on the lesion's optical extent. The proposed method of presenting data could prove to be a useful discriminative adjunct in the assessment of pigmented skin lesions.

  • 338.
    Imani, Roghayeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Iglič, Aleš
    Biophysics Laboratory, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia.
    Turner, Anthony P.F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Electrochemical detection of DNA damage through visible-light-induced ROS using mesoporous TiO2 microbeads2014In: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 40, p. 84-87Article in journal (Refereed)
    Abstract [en]

    Rapid detection of DNA damage could serve as a basis for genotoxicity studies of new bio-nanoconjugations. A novel TiO2 bio-nanoconjugation, consisting of mesoporous TiO2 microbeads, dopamine (DA) and ss-DNA, was constructed on fluorine-doped tin oxide-coated glass (FTO) and used for the detection of DNA damage in the photocatalytic reaction of TiO2 under visible light. Stable mesoporous TiO2 microbeads films were coated on FTO by the doctor-blade method; dopamine with oxygen containing ligands, was tightly coupled to the titanium surface prepaired under phase coordination. Specific single-strands of DNA were electronically linked to TiO2 by using a dopamine bridge. DNA damage, caused by reactive oxygen species (ROS) that were photogenerated through the photocatalytic reaction, was detected with square wave voltammetry (SWV) by recording the catalytic oxidation current of [Ru(NH3)6]3 +, an intercalated electroactive probe. The ability of antioxidant to protect DNA against damage in the photocatalytic reaction was also tested.

  • 339. Imura, Masataka
    et al.
    Kuroda, Tomohiro
    Oshiro, O
    Chihara, Kunihiro
    Brandberg, John
    Ask, Per
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Blood flow visualization in immersive environment based on color Doppler images2001In: PROCEEDINGS OF THE 23RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-4: BUILDING NEW BRIDGES AT THE FRONTIERS OF ENGINEERING AND MEDICINE, 2001, Vol. 23, p. 3167-3170Conference paper (Refereed)
    Abstract [en]

    An accurate grasp of blood flow patterns in a human heart is important to evaluate cardiac diseases of patients. Doppler ultrasound method is widely used to visualize blood flow patterns and has obtained excellent results in diagnosis. However, the output from Doppler ultrasound method is usually represented as a two-dimensional image, though blood flow patterns have three-dimensional complex structure and change dynamically. Therefore, improvement of both data acquisition and data visualization techniques is indispensable to diagnosis of cardiac faculty. It is worth mentioning that visualization also dominates the level of understanding as data acquisition, because poor visualization ruins the value of the most accurate result of measurement as if it were nothing. The authors construct an interactive visualization system suitable for three-dimensional blood flow, utilizing the immersive projection display. With the developed visualization system, which possesses interactivity and a wide field of view, users can easily understand the state of entire flow, such as the occurrence of turbulence, and the patterns of blood flow.

  • 340. Order onlineBuy this publication >>
    Iredahl, Fredrik
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Assessment of microvascular and metabolic responses in the skin2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The general aim of this project was to develop experimental in vivo models that allow for minimally invasive investigations of responses in the skin to microvascular and metabolic provocations. The cutaneous microvasculature has emerged as a valuable model and been proposed to mirror the microcirculation in other organs. Dysfunction in the cutaneous microcirculation has thus been linked to systemic diseases such as hypertension and diabetes mellitus. Models for investigating skin responses could facilitate the understanding of pathophysiological mechanisms as well as effects of drugs.

    In the first study, three optical measurement techniques (laser Doppler flowmetry (LDF), laser speckle contrast imaging (LSCI) and tissue viability imaging (TiVi)) were compared against each other and showed differences in their ability to detect microvascular responses to provocations in the skin. TiVi was found more sensitive for measurement of noradrenaline-induced vasoconstriction, while LSCI was more sensitive for measurement of vascular occlusion. In the second study, microvascular responses in the skin to iontophoresis of vasoactive drugs were found to depend on the drug delivery protocol. Perfusion half-life was defined and used to describe the decay in the microvascular response to a drug after iontophoresis. In the third study, the role of nitric oxide (NO) was assessed during iontophoresis of insulin. The results showed a NO-dependent vasodilation in the skin by insulin. In the fourth study the vasoactive and metabolic effects of insulin were studied after both local and endogenous administration. Local delivery of insulin increased skin blood flow, paralleled by increased skin concentrations of interstitial pyruvate and lactate, although no change in glucose concentration was observed. An oral glucose load resulted in an increased insulin concentration in the skin paralleled by an increase in blood flow, as measured using the microdialysis urea clearance technique, although no changes in perfusion was measured by LSCI.

    The thesis concludes that when studying skin microvascular responses, the choice of measurement technique and the drug delivery protocol has an impact on the measurement results, and should therefore be carefully considered. The thesis also concludes that insulin has metabolic and vasodilatory effects in the skin both when administered locally and as an endogenous response to an oral glucose load. The vasodilatory effect of insulin in the skin is mediated by nitric oxide.

    List of papers
    1. Non-Invasive Measurement of Skin Microvascular Response during Pharmacological and Physiological Provocations
    Open this publication in new window or tab >>Non-Invasive Measurement of Skin Microvascular Response during Pharmacological and Physiological Provocations
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    2015 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 8, p. 1-15, article id e0133760Article in journal (Refereed) Published
    Abstract [en]

    Introduction Microvascular changes in the skin due to pharmacological and physiological provocations can be used as a marker for vascular function. While laser Doppler flowmetry (LDF) has been used extensively for measurement of skin microvascular responses, Laser Speckle Contrast Imaging (LSCI) and Tissue Viability Imaging (TiVi) are novel imaging techniques. TiVi measures red blood cell concentration, while LDF and LSCI measure perfusion. Therefore, the aim of this study was to compare responses to provocations in the skin using these different techniques. Method Changes in skin microcirculation were measured in healthy subjects during (1) iontophoresis of sodium nitroprusside (SNP) and noradrenaline (NA), (2) local heating and (3) post-occlusive reactive hyperemia (PORH) using LDF, LSCI and TiVi. Results Iontophoresis of SNP increased perfusion (LSCI: baseline 40.9 +/- 6.2 PU; 10-min 100 +/- 25 PU; pless than0.001) and RBC concentration (TiVi: baseline 119 +/- 18; 10-min 150 +/- 41 AU; p = 0.011). No change in perfusion (LSCI) was observed after iontophoresis of NA (baseline 38.0 +/- 4.4 PU; 10-min 38.9 +/- 5.0 PU; p = 0.64), while RBC concentration decreased (TiVi: baseline 59.6 +/- 11.8 AU; 10-min 54.4 +/- 13.3 AU; p = 0.021). Local heating increased perfusion (LDF: baseline 8.8 +/- 3.6 PU; max 112 +/- 55 PU; pless than0.001, LSCI: baseline 50.8 +/- 8.0 PU; max 151 +/- 22 PU; pless than0.001) and RBC concentration (TiVi: baseline 49.2 +/- 32.9 AU; max 99.3 +/- 28.3 AU; pless than0.001). After 5 minutes of forearm occlusion with prior exsanguination, a decrease was seen in perfusion (LDF: p = 0.027; LSCI: pless than0.001) and in RBC concentration (p = 0.045). Only LSCI showed a significant decrease in perfusion after 5 minutes of occlusion without prior exsanguination (pless than0.001). Coefficients of variation were lower for LSCI and TiVi compared to LDF for most responses. Conclusion LSCI is more sensitive than TiVi for measuring microvascular changes during SNP-induced vasodilatation and forearm occlusion. TiVi is more sensitive to noradrenaline-induced vasoconstriction. LSCI and TiVi show lower inter-subject variability than LDF. These findings are important to consider when choosing measurement techniques for studying skin microvascular responses.

    Place, publisher, year, edition, pages
    Public Library of Science, 2015
    National Category
    Physiology
    Identifiers
    urn:nbn:se:liu:diva-121109 (URN)10.1371/journal.pone.0133760 (DOI)000359492800006 ()26270037 (PubMedID)
    Available from: 2015-09-07 Created: 2015-09-07 Last updated: 2019-04-29
    2. Modeling Perfusion Dynamics in the Skin During Iontophoresis of Vasoactive Drugs Using Single-Pulse and Multiple-Pulse Protocols
    Open this publication in new window or tab >>Modeling Perfusion Dynamics in the Skin During Iontophoresis of Vasoactive Drugs Using Single-Pulse and Multiple-Pulse Protocols
    Show others...
    2015 (English)In: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 22, no 6, p. 446-453Article in journal (Refereed) Published
    Abstract [en]

    Objective: After iontophoresis of vasoactive drugs into the skin, a decrease in perfusion is commonly observed. We delivered vasoactive drugs by iontophoresis using different delivery protocols to study how these affect this decrease in perfusion as measured using LDF. Methods: We measured skin perfusion during iontophoresis of (ACh), MCh, andNAusing a single pulse or separate pulses at different skin sites, and during repeated delivery of ACh at the same site. Results: Perfusion half-life was 6.1 (5.6-6.6) minutes for ACh and 41 (29-69) minutes for MCh (p less than 0.001). The maximum response with multiple pulses of ACh iontophoresis was lower than with a single pulse, 30 (22-37) PU vs. 43 (36-50) PU, p less than 0.001. Vasoconstriction to NA was more rapid with a single pulse than with multiple pulses. The perfusion half-life of ACh decreased with repeated delivery of ACh at the same site-first 16 (14-18), second 5.9 (5.1-6-9) and third 3.2 (2.9-3.5) minutes, p less than 0.001. Conclusions: The drug delivery protocol affects microvascular responses to iontophoresis, possibly as a result of differences in the dynamics of local drug concentrations. Perfusion half-life may be used as a measure to quantify the rate of perfusion recovery after iontophoresis of vasoactive drugs.

    Place, publisher, year, edition, pages
    Informa Healthcare / Wiley: 12 months, 2015
    Keywords
    microcirculation; iontophoresis; acetylcholine; metha choline; noradrenaline; skin
    National Category
    Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-121138 (URN)10.1111/micc.12211 (DOI)000359676500002 ()26016387 (PubMedID)
    Available from: 2015-09-08 Created: 2015-09-08 Last updated: 2017-12-04
    3. The Microvascular Response to Transdermal Iontophoresis of Insulin is Mediated by Nitric Oxide
    Open this publication in new window or tab >>The Microvascular Response to Transdermal Iontophoresis of Insulin is Mediated by Nitric Oxide
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    2013 (English)In: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 20, no 8, p. 717-723Article in journal (Refereed) Published
    Abstract [en]

    ObjectiveInsulin has direct effects on blood flow in various tissues, most likely due to endothelial NO production. We investigated whether insulin delivered to the skin by iontophoresis increases microvascular perfusion and whether this effect is partly or completely mediated by the release of NO. MethodsIn healthy subjects, regular insulin and monomeric insulin were delivered to the skin by cathodal iontophoresis. The skin was pretreated either with L-NAME or control solution (PBS) using anodal iontophoresis. Microvascular responses were measured using laser Doppler flowmetry. ResultsA dose-dependent increase in perfusion was observed during iontophoresis of regular and monomeric insulin. The maximum perfusion was significantly elevated compared with control after PBS (regular insulin 53.6 (12.7-95.6) PU vs. 4.2 (3.4-4.8) PU, p = 0.002; monomeric insulin 32.6 (8.9-92.6) PU vs. 5.9 (3.4-56.0) PU, p = 0.03). The microvascular response to insulin was abolished after L-NAME (regular insulin: 25.6 (11.6-54.4) PU vs. control: 4.7 (2.9-11.5) PU, p = 0.15; monomeric insulin 10.9 (5.4-56.8) PU vs. control: 4.7 (2.9-11.5) PU, p = 0.22). ConclusionsThe main finding is that iontophoresis of insulin induces a dose-dependent vasodilation in the skin, which could be suppressed after pretreatment with a NO synthase inhibitor. This suggests that vasodilation in the skin after iontophoresis of insulin is mediated by the NO pathway.

    Place, publisher, year, edition, pages
    WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA, 2013
    Keywords
    insulin, transdermal iontophoresis, endothelial function, vasodilation
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-102080 (URN)10.1111/micc.12071 (DOI)000326607600008 ()
    Note

    Funding Agencies|Linkoping University||County Council of Ostergotland||

    Available from: 2013-12-02 Created: 2013-11-29 Last updated: 2017-12-06
    4. Skin glucose metabolism and microvascular blood flow during local insulin delivery and after an oral glucose load
    Open this publication in new window or tab >>Skin glucose metabolism and microvascular blood flow during local insulin delivery and after an oral glucose load
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    2016 (English)In: Microcirculation, ISSN 1073-9688, E-ISSN 1549-8719, Vol. 23, no 7, p. 597-605Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVE: Insulin causes capillary recruitment in muscle and adipose tissue, but the metabolic and microvascular effects of insulin in the skin have not been studied in detail. The aim of this study was to measure glucose metabolism and microvascular blood flow in the skin during local insulin delivery and after an oral glucose load.

    METHODS: Microdialysis catheters were inserted intracutanously in human subjects. In eight subjects two microdialysis catheters were inserted, one perfused with insulin and one with control solution. First the local effects of insulin was studied, followed by a systemic provocation by an oral glucose load. Additionally, as control experiment, six subjects did not recieve local delivery of insulin or the oral glucose load. During microdialysis the local blood flow was measured by urea clearance and by laser speckle contrast imaging (LSCI).

    RESULTS: Within 15 minutes of local insulin delivery, microvascular blood flow in the skin increased (urea clearance: P=.047, LSCI: P=.002) paralleled by increases in pyruvate (P=.01) and lactate (P=.04), indicating an increase in glucose uptake. An oral glucose load increased urea clearance from the catheters, indicating an increase in skin perfusion, although no perfusion changes were detected with LSCI. The concentration of glucose, pyruvate and lactate increased in the skin after the oral glucose load.

    CONCLUSION: Insulin has metabolic and vasodilatory effects in the skin both when given locally and after systemic delivery through an oral glucose load.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2016
    National Category
    Endocrinology and Diabetes Physiology Clinical Medicine Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:liu:diva-132368 (URN)10.1111/micc.12325 (DOI)000386946300014 ()27681957 (PubMedID)
    Note

    Funding agencies: ALF grants; Region Ostergotland; Sinnescentrum; Gronberg Foundation

    Available from: 2016-11-01 Created: 2016-11-01 Last updated: 2018-01-13Bibliographically approved
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  • 341.
    Jackowski, Christian
    et al.
    Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Bolliger, Stephan
    Univ Bern, Inst Forens Med, Ctr Forens Imaging & Virtopsy, CH-3012 Bern, Switzerland.
    Thali, Michael J.
    Univ Bern, Inst Forens Med, Ctr Forens Imaging & Virtopsy, CH-3012 Bern, Switzerland.
    Scenes from the past - Common and unexpected findings in mummies from ancient Egypt and South America as revealed by CT2008In: Radiographics, ISSN 0271-5333, E-ISSN 1527-1323, Vol. 28, no 5, p. 1477-1492Article in journal (Refereed)
    Abstract [en]

    Computed tomography (CT) has proved to be a valuable investigative tool for mummy research and is the method of choice for examining mummies. It allows for noninvasive insight, especially with virtual endoscopy, which reveals detailed information about the mummy's sex, age, constitution, injuries, health, and mummification techniques used. CT also supplies three-dimensional information about the scanned object. Mummification processes can be summarized as "artificial," when the procedure was performed on a body with the aim of preservation, or as "natural," when the body's natural environment resulted in preservation. The purpose of artificial mummification was to preserve that person's morphologic features by delaying or arresting the decay of the body. The ancient Egyptians are most famous for this. Their use of evisceration followed by desiccation with natron (a compound of sodium salts) to halt putrefaction and prevent rehydration was so effective that their embalmed bodies have survived for nearly 4500 years. First, the body was cleaned with a natron solution, then internal organs were removed through the cribriform plate and abdomen. The most important, and probably the most lengthy, phase was desiccation. After the body was dehydrated, the body cavities were rinsed and packed to restore the body's former shape. Finally, the body was wrapped. Animals were also mummified to provide food for the deceased, to accompany the deceased as pets, because they were seen as corporal manifestations of deities, and as votive offerings. Artificial mummification was performed on every continent, especially in South and Central America. (C) RSNA, 2008 . radiographics.rsnajnls.org.

  • 342.
    Jager, Edwin
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Book Review: Microfluidics in Detection Science – Lab-on-a-Chip Technologies, H.O. Fatoyinbo, F.H. Labeed (Eds.). Royal Society of Chemistry, Cambridge (2015). 281 pp., £145 GBP, ISBN 978-84973-638-12015In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 71, p. 483-484Article in journal (Refereed)
  • 343.
    Janerot-Sjöberg, Birgitta
    et al.
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Ekberg, Stefan
    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.
    Areskog, M.
    Department of Clinical Physiology, Kalmar Regional Hospital.
    Nylander, Eva
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    Swahn, Eva
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Cardiology UHL.
    Quantitative digital evaluation of myocardial exercise thallium-201 single-photon emission tomography in post-menopausal women1998In: Clinical Physiology, ISSN 0144-5979, E-ISSN 1365-2281, Vol. 18, no 3, p. 169-177Article in journal (Refereed)
    Abstract [en]

    Quantitative computerized analysis of data from myocardial thallium-201 (201Tl) single-photon emission tomography (SPET) may improve the diagnostic accuracy of coronary heart disease. The reference ranges for post-menopausal women are, however, limited and obtained mainly from patients. To compare reference values from healthy post-menopausal women and to improve the quantitative analysis, 20 women (10 patients with coronary heart disease and previous infarction and 10 age-matched healthy volunteers) were examined immediately post exercise and after a delay. A nine-segment 'bull's-eye' model was used for analysis. At visual evaluation, reproducibility was high (93%), no false-positive results were obtained and in 70% of the patients the SPET was interpreted as abnormal. Using reported reference values for quantitative analysis, all the healthy women had an abnormal result. New reference values based on three different methods of 'normalization' were calculated: the relative activity of segment 3 set to 100%, the segment with the highest activity set to 100% and a least-squares method. They all differed significantly from those that had previously been reported. The frequencies of agreement between visual and quantitative analysis were 84-92% and were highest when segment 3 was used as a reference, but in this case only 40% of the patients with coronary heart disease had an abnormal SPET. Using the least-squares method for handling digital information, the SD of the normal values decreased and 90% of the patients with coronary heart disease were accurately diagnosed. These results provide quantitative digital reference values for healthy post-menopausal women. They verify that quantitative analysis is in diagnostic agreement with visual evaluation, stress the need for local verification of reference ranges and suggest a least-square normalization method for the analysis.

  • 344.
    Jankowai, Jochen
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Englund, Rickard
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ropinski, Timo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Institute of Media Informatics, Ulm University, Tyskland.
    Hotz, Ingrid
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Interactive 4D MRI blood flow exploration and analysis using line predicates2016In: Proceedings of SIGRAD 2016: May 23rd and 24th, Visby, Sweden / [ed] Masaki Hayashi, Linköping: Linköping University Electronic Press, 2016, p. 35-42Conference paper (Refereed)
    Abstract [en]

    We present an interactive exploration tool for 4D PC-MRI blood flow data that incorporates established rendering and filtering methods and combine them into one application. These methods include advanced line illumination, interactively adjustable spatial context visualization and blood flow analysis using line predicates.

  • 345.
    Jeuthe, Julius
    Linköping University, Department of Biomedical Engineering, Medical Informatics.
    Automatic Tissue Segmentation of Volumetric CT Data of the Pelvic Region2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Automatic segmentation of human organs allows more accurate calculation of organ doses in radiationtreatment planning, as it adds prior information about the material composition of imaged tissues. For instance, the separation of tissues into bone, adipose tissue and remaining soft tissues allows to use tabulated material compositions of those tissues. This approximation is not perfect because of variability of tissue composition among patients, but is still better than no approximation at all. Another use for automated tissue segmentationis in model based iterative reconstruction algorithms. An example of such an algorithm is DIRA, which is developed at the Medical Radiation Physics and the Center for Medical Imaging Science and Visualization(CMIV) at Linköpings University. DIRA uses dual-energy computed tomography (DECT) data to decompose patient tissues into two or three base components. So far DIRA has used the MK2014 algorithm which segments human pelvis into bones, adipose tissue, gluteus maximus muscles and the prostate. One problem was that MK2014 was limited to 2D and it was not very robust.

    Aim: The aim of this thesis work was to extend the MK2014 to 3D as well as to improve it. The task was structured to the following activities: selection of suitable segmentation algorithms, evaluation of their results and combining of those to an automated segmentation algorithm. Of special interest was image registration usingthe Morphon.

    Methods: Several different algorithms were tested.  For instance: Otsu's method followed by threshold segmentation; histogram matching followed by threshold segmentation, region growing and hole-filling; affine phase-based registration and the Morphon. The best-performing algorithms were combined into the newly developed JJ2016.

    Results: For the segmentation of adipose tissue and the bones in the eight investigated data sets, the JJ2016 algorithm gave better results than the MK2014. The better results of the JJ2016 were achieved by: (i) a new segmentation algorithm for adipose tissue which was not affected by the amount of air surrounding the patient and segmented smaller regions of adipose tissue and (ii) a new filling algorithm for connecting segments of compact bone. The JJ2016 algorithm also estimates a likely position for the prostate and the rectum by combining linear and non-linear phase-based registration for atlas based segmentation. The estimated position (center point) was in most cases close to the true position of the organs. Several deficiencies of the MK2014 algorithm were removed but the improved version (MK2014v2) did not perform as well as the JJ2016.

    Conclusions: JJ2016 performed well for all data sets. The JJ2016 algorithm is usable for the intended application, but is (without further improvements) too slow for interactive usage. Additionally, a validation of the algorithm for clinical use should be performed on a larger number of data sets, covering the variability of patients in shape and size.

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  • 346.
    Jin, Qiangguo
    et al.
    School of Computer Software, College of Intelligence and Computing, Tianjin University, Tianjin, China.
    Meng, Zhaopeng
    School of Computer Software, College of Intelligence and Computing, Tianjin University, Tianjin, China; Tianjin University of Traditional Chinese Medicine, Tianjin, China.
    Pham, Tuan
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Chen, Qi
    School of Computer Software, College of Intelligence and Computing, Tianjin University, Tianjin, China.
    Wei, Leyi
    School of Computer Science and Technology, College of Intelligence and Computing, Tianjin University, Tianjin, China.
    Su, Ran
    School of Computer Software, College of Intelligence and Computing, Tianjin University, Tianjin, China.
    DUNet: A deformable network for retinal vessel segmentation2019In: Knowledge-Based Systems, ISSN 0950-7051, E-ISSN 1872-7409, Vol. 178, p. 149-162Article in journal (Refereed)
    Abstract [en]

    Automatic segmentation of retinal vessels in fundus images plays an important role in the diagnosis of some diseases such as diabetes and hypertension. In this paper, we propose Deformable U-Net (DUNet), which exploits the retinal vessels’ local features with a U-shape architecture, in an end to end manner for retinal vessel segmentation. Inspired by the recently introduced deformable convolutional networks, we integrate the deformable convolution into the proposed network. The DUNet, with upsampling operators to increase the output resolution, is designed to extract context information and enable precise localization by combining low-level features with high-level ones. Furthermore, DUNet captures the retinal vessels at various shapes and scales by adaptively adjusting the receptive fields according to vessels’ scales and shapes. Public datasets: DRIVE, STARE, CHASE_DB1 and HRF are used to test our models. Detailed comparisons between the proposed network and the deformable neural network, U-Net are provided in our study. Results show that more detailed vessels can be extracted by DUNet and it exhibits state-of-the-art performance for retinal vessel segmentation with a global accuracy of 0.9566/0.9641/0.9610/0.9651 and AUC of 0.9802/0.9832/0.9804/0.9831 on DRIVE, STARE, CHASE_DB1 and HRF respectively. Moreover, to show the generalization ability of the DUNet, we use another two retinal vessel data sets, i.e., WIDE and SYNTHE, to qualitatively and quantitatively analyze and compare with other methods. Extensive cross-training evaluations are used to further assess the extendibility of DUNet. The proposed method has the potential to be applied to the early diagnosis of diseases.

  • 347.
    Jogestrand, Tomas
    et al.
    Karolinska Institute, Sweden; Karolinska University Hospital, Sweden.
    Freden-Lindqvist, Johan
    Sahlgrens University Hospital, Sweden.
    Lindqvist, Madeleine
    Karolinska University Hospital, Sweden.
    Lundgren, Susanne
    Blekingesjukhuset, Sweden.
    Tillman, Ann-Sofie
    Region Östergötland, Center for Diagnostics, Department of Clinical Physiology in Norrköping.
    Zachrisson, Helene
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Discrepancies in recommended criteria for grading of carotid stenosis with ultrasound2016In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 36, no 4, p. 326-329Article in journal (Refereed)
    Abstract [en]

    The accuracy of duplex ultrasound for grading of internal carotid artery stenosis has been widely tested and shown to be high. However, different methods for measurement of the degree of carotid stenosis with the golden standard conventional angiography have been used in the different studies. This, together with other factors, has led to some confusion regarding the relation between the ultrasonographically measured flow velocity and the angiographically measured degree of stenosis. The ultrasound criteria that are used in Sweden (and in Germany) differ in an important way from the criteria recommended in North America and the United Kingdom for the same degree of angiographic stenoses. Possible reasons for the discrepancies are discussed in this article. The authors recommend absolute agreement locally whether ECST or NASCET criteria shall be used in the communication between radiologists, clinical physiologists, vascular surgeons, neurologists and other physicians involved in patient management decisions. Angle-dependent ultrasound criteria should be used and flow velocity measurements with ultrasound should be combined with assessment of plaque burden on 2D picture.

  • 348.
    Johansson, Anders
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Sundqvist, Tommy
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology.
    Kuiper, J.-H.
    Keele University School of Medicine, Keele, UK .
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    A spectroscopic approach to imaging and quantification of cartilage lesions in human knee joints2011In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 56, no 6, p. 1865-1878Article in journal (Refereed)
    Abstract [en]

    We have previously described a technology based on diffuse reflectance of broadband light for measuring joint articular cartilage thickness, utilizing that optical absorption is different in cartilage and subchondral bone. This study is the first evaluation of the technology in human material. We also investigated the prospects of cartilage lesion imaging, with the specific aim of arthroscopic integration. Cartilage thickness was studied ex vivo in a number of sites (n = 87) on human knee joint condyles, removed from nine patients during total knee replacement surgery. A reflectance spectrum was taken at each site and the cartilage thickness was estimated using the blue, green, red and near-infrared regions of the spectrum, respectively. Estimated values were compared with reference cartilage thickness values (taken after sample slicing) using an exponential model. Two-dimensional Monte Carlo simulations were performed in a theoretical analysis of the experimental results. The reference cartilage thickness of the investigated sites was 1.60 ± 1.30 mm (mean ± SD) in the range 0–4.2 mm. Highest correlation coefficients were seen for the calculations based on the near-infrared region after normalization to the red region (r = 0.86) and for the green region (r = 0.80).

  • 349.
    Johansson, Björn
    Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Opacification of anterior part of hydrophilic acrylic IOL or a prelenticular inflammatory membrane?2012In: Journal of cataract and refractive surgery, ISSN 0886-3350, E-ISSN 1873-4502, Vol. 38, no 6, p. 1115-1116Article in journal (Refereed)
    Abstract [en]

    In their recent case report, Park and Chuck1 describe the bilateral appearance of an opacification at the plane of the anterior surface of the hydrophilic acrylic Akreos MI60 intraocular lens (IOL) (Bausch & Lomb). The patient's general history of diabetes mellitus, proliferative retinopathy, and iris rubeosis explains the limited pupil dilation preventing visualization of the capsulorhexis opening in their slitlamp images.

  • 350. Order onlineBuy this publication >>
    Johansson, Gustaf
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    A Global Linear Optimization Framework for Adaptive Filtering and Image Registration2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Digital medical atlases can contain anatomical information which is valuable for medical doctors in diagnosing and treating illnesses. The increased availability of such atlases has created an interest for computer algorithms which are capable of integrating such atlas information into patient specific dataprocessing. The field of medical image registration aim at calculating how to match one medical image to another. Here the atlas information could give important hints of which kinds of motion are plausible in different locations of the anatomy. Being able to incorporate such atlas specific information could potentially improve the matching of images and plausibility of image registration - ultimately providing a more correct information on which to base health care diagnosis and treatment decisions.

    In this licentiate thesis a generic signal processing framework is derived : Global Linear Optimization (GLO). The power of the GLO framework is first demonstrated quantitatively in a very high performing image denoiser. Important proofs of concepts are then made deriving and implementing three important capabilities regarding adaptive filtering of vector fields in medica limage registration:

    1. Global regularization with local anisotropic certainty metric.
    2. Allowing sliding motion along organ and tissue boundaries.
    3. Enforcing an incompressible motion in specific areas or volumes.

    In the three publications included in this thesis, the GLO framework is shown to be able to incorporate one each of these capabilities. In the third and final paper a demonstration is made how to integrate more and more of the capabilities above into the same GLO to perform adaptive processing on relevant clinical data. It is shown how each added capability improves the result of the image registration. In the end of the thesis there is a discussion which highlights the advantage of the contributions made as compared to previous methods in the scientific literature.

    List of papers
    1. Globally Optimal Displacement Fields Using Local Tensor Metric
    Open this publication in new window or tab >>Globally Optimal Displacement Fields Using Local Tensor Metric
    2012 (English)In: Image Processing (ICIP), 2012 19th IEEE International Conference on, 2012, p. 2957-2960Conference paper, Poster (with or without abstract) (Other academic)
    Abstract [en]

    In this paper, we propose a novel algorithm for regularizing displacement fields in image registration. The method uses the local structure tensor and gradients of the displacement field to impose a local metric, which is then used optimizing a global cost function. The method allows for linear operators, such as tensors and differential operators modeling the underlying physical anatomy of the human body in medical images. The algorithm is tested using output from the Morphon image registration algorithm on MRI data as well as synthetic test data and the result is compared to the initial displacement field. The results clearly demonstrate the power of the method and the unique features brought forth through the global optimization approach.

    Keywords
    Image Processing, Image Registration, Regularization, Optimization, Tensor
    National Category
    Medical Image Processing Signal Processing
    Identifiers
    urn:nbn:se:liu:diva-81947 (URN)10.1109/ICIP.2012.6467520 (DOI)978-1-4673-2534-9 (ISBN)
    Conference
    2012 IEEE International Conference on Image Processing, September 30 - October 3, 2012, Orlando, Florida, USA
    Projects
    Dynamic Context Atlases for Image Denoising and Patient Safety
    Funder
    Swedish Research Council, 2011-5176Swedish Research Council, 2007-4786
    Available from: 2012-09-26 Created: 2012-09-26 Last updated: 2015-04-17Bibliographically approved
    2. Motion Field Regularization for Sliding Objects using Global Linear Optimization
    Open this publication in new window or tab >>Motion Field Regularization for Sliding Objects using Global Linear Optimization
    2015 (English)Conference paper, Oral presentation only (Refereed)
    Abstract [en]

    In image registration it is often necessary to employ  regularization in one form or another to be able to find a plausible  displacement field. In medical applications, it is useful to define  different constraints for different areas of the data. For instance  to measure if organs have moved as expected after a finished  treatment. One common problem is how to find plausible motion  vectors far away from known motion. This paper introduces a new  method to build and solve a Global Linear Optimizations (GLO)  problem with a novel set of terms which enable specification of  border areas to allow a sliding motion. The GLO approach is  important especially because it allows simultaneous incorporation of  several different constraints using information from medical atlases  such as localization and properties of organs. The power and  validity of the method is demonstrated using two simple, but  relevant 2D test images. Conceptual comparisons with previous  methods are also made to highlight the contributions made in this  paper. The discussion explains important future work and experiments  as well as exciting future improvements to the GLO framework.

    Keywords
    Image Registration, Missing Data, Medical Image Processing, Global Linear Optimization
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-112210 (URN)
    Conference
    The 4th International Conference on Pattern Recognition Applications and Methods, Januari 10-12, Lisbon, Portugal
    Projects
    Dynamic Context Atlases for Image Denoising and Patient SafetyGlobal Linear Optimization
    Funder
    Swedish Research Council, 2011-5176Linnaeus research environment CADICS
    Available from: 2014-11-18 Created: 2014-11-18 Last updated: 2015-04-17Bibliographically approved
    3. Regularization in Medical Image Registration using Global Linear Optimization
    Open this publication in new window or tab >>Regularization in Medical Image Registration using Global Linear Optimization
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Common problems in image registration include having large parts of the images contain noisy, uncertain, missing or impossible motion. Regularization is the field that aims to overcome these problems. In this article, we propose a novel framework : Global Linear Optimization (GLO) which we demonstrate has the capabilities to simultaneously and globally regularize with respect to : (1) anisotropic certainty of prior motion field, (2) sliding of organ boundaries and (3) incompressibility of organ interiors. The power of the presented framework consists of being able to spatially adapt which subsets of the data each constraint should affect and then solve a large sparse linear equations system which automatically propagates a solution over the data set through an overlapping localized metric. We demonstrate the validity of the methods and the power of the GLO framework on relevant test cases and on medical data from the DIR-lab.

    Keywords
    Keywords—Image Registration, Medical Image Analysis, Regularization, Adaptive Filtering, Medical Atlases, Global Methods, Optimization, Global Linear Optimization, Structure Tensor, Anisotropic Filtering, Partial Differential Equations
    National Category
    Medical Image Processing Other Computer and Information Science
    Identifiers
    urn:nbn:se:liu:diva-117140 (URN)
    Available from: 2015-04-17 Created: 2015-04-17 Last updated: 2018-01-11Bibliographically approved
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