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Improved estimation and visualization of two-dimensional myocardial strain rate using MR velocity mapping
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.
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. (Department of Radiology, Stanford University, Stanford, California, USA)
Linköping University, Department of Medical and Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences.
Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping. (Department of Medicine, University of California San Francisco, San Francisco, California, USA)
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2008 (English)In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 28, no 3, 604-611 p.Article 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.

Place, publisher, year, edition, pages
2008. Vol. 28, no 3, 604-611 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-43136DOI: 10.1002/jmri.21471ISI: 000259106900007Local ID: 71981OAI: oai:DiVA.org:liu-43136DiVA: diva2:263994
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
In thesis
1. Assessment of Myocardial Function using Phase Based Motion Sensitive MRI
Open this publication in new window or tab >>Assessment of Myocardial Function using Phase Based Motion Sensitive MRI
2010 (English)Doctoral 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.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 53 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1341
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-60027 (URN)978-91-7393-302-5 (ISBN)
Public defence
2010-11-12, Conrad, Universitetssjukhuset, Campus US, Linköpings universitet, Linköping, 09:15 (English)
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Available from: 2010-11-16 Created: 2010-10-04 Last updated: 2016-03-14Bibliographically approved

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Haraldsson, HenrikWigström, LarsBolger, Ann FEngvall, JanEbbers, TinoEscobar Kvitting, John-Peder

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Haraldsson, HenrikWigström, LarsBolger, Ann FEngvall, JanEbbers, TinoEscobar Kvitting, John-Peder
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Center for Medical Image Science and Visualization (CMIV)Clinical PhysiologyFaculty of Health SciencesDepartment of Medical and Health SciencesDepartment of Clinical Physiology in LinköpingDepartment of Clinical PhysiologyDepartment of Thoracic and Vascular Surgery
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Journal of Magnetic Resonance Imaging
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