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Kinematics of the heart: strain-rate imaging from time-resolved three-dimensional phase contrast MRI
Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
Linköping University, Department of Biomedical Engineering. Linköping University, Department of Medicine and Care.
Linköping University, Department of Medicine and Care. Linköping University, Faculty of Health Sciences.ORCID iD: 0000-0003-1395-8296
Linköping University, Department of Biomedical Engineering. Linköping University, Department of Medicine and Care. Linköping University, Faculty of Health Sciences.
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2002 (English)In: IEEE Transactions on Medical Imaging, ISSN 0278-0062, E-ISSN 1558-254X, Vol. 21, no 9, 1105-1109 p.Article in journal (Refereed) Published
Abstract [en]

A four-dimensional mapping (three spatial dimensions + time) of myocardial strain-rate would help to describe the mechanical properties of the myocardium, which affect important physiological factors such as the pumping performance of the ventricles. Strain-rate represents the local instantaneous deformation of the myocardium and can be calculated from the spatial gradients of the velocity field. Strain-rate has previously been calculated using one-dimensional (ultrasound) or two-dimensional (2-D) magnetic resonance imaging techniques. However, this assumes that myocardial motion only occurs in one direction or in one plane, respectively. This paper presents a method for calculation of the time-resolved three-dimensional (3-D) strain-rate tensor using velocity vector information in a 3-D spatial grid during the whole cardiac cycle. The strain-rate tensor provides full information of both magnitude and direction of the instantaneous deformation of the myocardium. A method for visualization of the full 3-D tensor is also suggested. The tensors are visualized using ellipsoids, which display the principal directions of strain-rate and the ratio between strain-rate magnitude in each direction. The presented method reveals the principal strain-rate directions without a priori knowledge of myocardial motion directions.

Place, publisher, year, edition, pages
2002. Vol. 21, no 9, 1105-1109 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-26711DOI: 10.1109/TMI.2002.804431Local ID: 11305OAI: oai:DiVA.org:liu-26711DiVA: diva2:247261
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13
In thesis
1. Automated feature detection in multidimensional images
Open this publication in new window or tab >>Automated feature detection in multidimensional images
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Manual identification of structures and features in multidimensional images is at best time consuming and operator dependent. Feature identification need to be accurate, repeatable and quantitative.

This thesis presents novel methods for automated feature detection in multidimensional images that are independent on imaging modality. Feature detection is described at two abstraction levels. At the first low level the image is regionally processed to find local or regional features. In the second medium level results are taken from the low level feature detection and grouped into objects or parts that can be quantified. A key to quantification of cardiac function is delineation of the cardiac walls which is a difficult task. Two different methods are described and evaluated for delineation of the left ventricular wall from anatomical images. The results show that semi-automatic delineation is a huge time saver compared to manual delineation. To obtain a robust results as much a priori and image information as possible should be used in the delineation process. Regional cardiac wall function is further studied by deriving and analyzing strain-rate tensors from velocity encoded images. For flow encoded images novel methods to find regional flow structures such as vortex cores, flow based delineation, and flow quantification are proposed. These methods are applied to study blood flow in the human heart, but the techniques outlined are general and can be applied to a wide array of flow conditions.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2005. 70 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 917
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-29497 (URN)14852 (Local ID)91-85297-10-0 (ISBN)14852 (Archive number)14852 (OAI)
Public defence
2005-04-15, Elsa Brändströmsalen, Campus US, Linköpings Universitet, Linköping, 13:00 (English)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-12-10Bibliographically approved
2. Kinematics of the heart: strain and strain-rate using time-resolved three-dimensional phase contrast MRI
Open this publication in new window or tab >>Kinematics of the heart: strain and strain-rate using time-resolved three-dimensional phase contrast MRI
2004 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

During the cardiac cycle, the myocardium (heart muscle) undergoes large elastic deformations as a consequence of the active muscle contraction along the muscle :fibers and their relaxation, respectively. A four-dimensional (4D) description (three spatial dimensions + time) of the kinematics of the myocardium would bring increased understanding of the mechanical properties of the heart and may be of interest in assessing regional myocardial function.

The heart is a complex three-dimensional structure and therefore velocity components in three directions are necessary to accurately describe the velocities in the myocardium. The phase contrast MRI pulse sequence used in this work provides velocity vectors in a 3D spatial grid covering the entire heart throughout the cardiac cycle. The suggested method provides the strain-rate tensor in each measured voxel and time frame of the cardiac cycle, calculated from the velocity field. Coordinates for the measured voxels,obtained from the velocity data, defme the deformation of a finite element mesh. This mesh is used for calculation of myocardial strain.

The method presented in this thesis enables automated delineation of the borders of the myocardium, definition of a parametric fmite element mesh and calculation of 4D myocardial strain and strain-rate throughout the cardiac cycle. The suggested visualization method displays the full tensors, including the main direction of deformation or deformation rate without any assumptions of myocardial motion directions in the calculations.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2004. 44 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1097
Series
LiU-TEK-LIC, 24
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-33626 (URN)19661 (Local ID)91-7373-970-7 (ISBN)19661 (Archive number)19661 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2013-11-25

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Selskog, PernillaHeiberg, EinarEbbers, TinoWigström, LarsKarlsson, Matts

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Selskog, PernillaHeiberg, EinarEbbers, TinoWigström, LarsKarlsson, Matts
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IEEE Transactions on Medical Imaging
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