Figure 2. Procedure for determining plaque volumes from 3D ultrasound images.

a) An approximate axis of the vessel is selected in a longitudinal view (colored line) and the internal elastic lamina and lumen boundary are outlined (yellow). b) Using the surfaces generated by the vessel contours and the 3D ultrasound image, the position of the bifurcation (BF; yellow arrow) is determined and marked. The axis of the vessel is selected based on the bifurcation point and marked along the branch as far as the plaque can be measured (colored line). This axis will be used as a reference for distance measurements. c) All plaques within the measurable distance are outlined, different colors being used for each separate plaque to aid in identification. d) Volumes are calculated for each plaque, and surfaces of the vessel wall and plaques are generated to better visualize the plaques in relation to the carotid arteries. Reproduced by permission of Wolters Kluwer from: Ainsworth CD, Blake CC, Tamayo A, Beletsky V, Fenster A, Spence JD: 3D ultrasound measurement of change in carotid plaque volume: a tool for rapid evaluation of new therapies. Stroke 2005, 36(9): 1904–1909.