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Region-based active contours for computer-aided analysis of carotid Phase Contrast MRI

Phase-Contrast (PC) velocimetry MRI is a useful modality to explore cardiovascular pathologies, but requires the automatic segmentation of vessels. In this paper, we evaluate the ability of region-based active contours to efficiently segment carotid vessels, compared to traditionnal edge-based active contours considered in related works. Experiments are performed using both a sequence of a homemade phantom and a sequence of a patient carotid which has been manually analyzed by a radiologist expert. Results obtained on phantom sequence show that the edge-based approach leads to an underestimate of carotid lumen area and related flows of respectively 18.4 % and 3.6 %. This appears significantly larger than weak errors obtained using the region-based approach (respectively 2.3 % and 0.7 %). Benefits appear even better on the patient sequence. The edge-based approach leads to underestimates of 20.5 % for areas and 13.8 % for blood flows, compared to limited errors of 5.2 % and 4 % with our proposal. This improvement is confirmed by similarity indices used to compare segmentations.