  Purpose: Echocardiography is commonly used as a non-invasive imaging tool in
clinical practice for the assessment of cardiac function. However, delineation
of the left ventricle is challenging due to the inherent properties of
ultrasound imaging, such as the presence of speckle noise and the low
signal-to-noise ratio. Methods: We propose a semi-automated segmentation
algorithm for the delineation of the left ventricle in temporal 3D
echocardiography sequences. The method requires minimal user interaction and
relies on a diffeomorphic registration approach. Advantages of the method
include no dependence on prior geometrical information, training data, or
registration from an atlas. Results: The method was evaluated using
three-dimensional ultrasound scan sequences from 18 patients from the
Mazankowski Alberta Heart Institute, Edmonton, Canada, and compared to manual
delineations provided by an expert cardiologist and four other registration
algorithms. The segmentation approach yielded the following results over the
cardiac cycle: a mean absolute difference of 1.01 (0.21) mm, a Hausdorff
distance of 4.41 (1.43) mm, and a Dice overlap score of 0.93 (0.02).
Conclusions: The method performed well compared to the four other registration
algorithms.
