On the use of block matching for the estimation of arterial wall motion

Motion of the carotid artery wall is important for the quantification of arterial elasticity and contractility and can be estimated from sequences of B-mode ultrasound images. In the relatively few studies on the subject, block matching has been used to estimate displacements of selected areas of the arterial wall and of the atheromatous plaque. In this paper, we attempted a small study on the use and performance of three variations of block matching, namely forward-, backward- and combination-block-matching, in terms of estimating arterial wall motion. Simulated ultrasound image sequences, generated using (a) FIELD-II, an ultrasound simulation package and (b) a mathematical model of arterial wall displacement, were used. The warping index, defined as the mean geometric error in pixels between the true and recovered deformation, was used to evaluate the performance of the block matching techniques. Reasonably high values were obtained for all three cases; specifically, the warping index was 1.879 for forward-, 0.984 for backward- and 1.122 for combined block matching. In conclusion, block matching techniques are appropriate for estimating arterial wall motion from sequences of ultrasound images; backward tracking may be the preferred technique in such applications.