Carotid artery wall motion estimated from B-mode ultrasound using region tracking and block matching.

The motion of the carotid atheromatous plaque relative to the adjacent wall may be related to the risk of cerebral events. A quantitative method for motion estimation was applied to analyse arterial wall movement from sequences of 2-D B-mode ultrasound (US) images. Image speckle patterns were tracked between successive frames using the correlation coefficient as the matching criterion. The size of the selected region-of-interest (ROI) was shown to affect the motion analysis results; an optimal size of 3.2 x 2.5 mm(2) was suggested for tracking a region at the wall-lumen interface and of 6.3 x 2.5 mm(2) for one within the tissue. The results showed expected cyclical motion in the radial direction and some axial movement of the arterial wall. The method can be used to study further the axial motion of the carotid artery wall and plaque and, thus, provide useful insight into the mechanisms of atherosclerosis.