Motion Analysis In Three Dimensional Ultrasound Plane-Wave Excitation Imaging By Feature Tracking
Date Issued
2012
Date
2012
Author(s)
Tseng, Lin-Yi
Abstract
Echocardiographic strain imaging is a clinical tool to assess the myocardial motion. Speckle tracking is typically applied to detect displacement of speckles on endocardium and epicardium. Furthermore, it can estimate the myocardial strain to help clinicians to evaluate cardiac functions, but its clinical applications are mainly limited to two-dimensions. As the heart is the fastest-moving organ, and is associated with elongation, shortening, torsion movement patterns, it is necessary to develop real-time three-dimensional strain echocardiography image for the acquisition of complete information of such a complex deformation. In view of the fact that plane-wave excitation imaging has the highest frame rate which makes it possible to achieve real-time three-dimensional imaging, and that the other feature tracking method derived from the speckle tracking method is able to solve the problem that three-dimensional speckle tracking is too computationally intensive for practical use, the aim of this study is to combine the plane-wave excitation imaging method and the feature tracking method to construct three-dimensional echocardiographic strain images. In this study, we simulate three-dimensional plane-wave excitation (PWE) images with object motion on which speckle tracking and feature tracking methods are applied and their efficacies are compared. The results show that PWE images result in greater tracking errors in lateral displacements when compared with two-way focused images. In addition, better tracking results can be obtained if the speckle tracking algorithm is implemented in polar coordinates. Furthermore, although the feature tracking method is more computationally efficient than the traditional speckle tracking method, its tracking error is relatively large. On the other hand, when applied on the rotated images, the feature tracking method and the speckle tracking method both have good tracking accuracy, but the error in the feature tracking case is still larger. In the feature tracking algorithm, the greater the threshold or the larger kernel size is set, the higher the tracking accuracy will be, but the number of feature patterns will also decrease. According to the results above, we believe that it is feasible to combine the plane-wave excitation imaging with feature tracking to constitute three-dimensional echocardiographic strain imaging. Finally, we apply feature tracking to clinical three-dimensional echocardiographic data of a three-month-old baby. Due to limited image quality, the feature patterns of endocardium and epicardium are not representative of the overall movement of the heart. Future researches will deal with the problems of the feature tracking method in clinical applications.
Subjects
echocardiographic strain imaging
speckle tracking
feature tracking
high frame rate imaging
plane-wave excitation imaging
Type
thesis
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