Aortic Thrombus Segmentation using Narrow Band Active Contour Model

This paper proposes 2D active contour approach for segmenting thrombus volume from 3D CT images of abdominal aortic aneurysm (AAA). The major challenges in segmenting thrombus are in part because of lack of delineating contrast at anatomical boundaries due to overlap of other soft tissues and artifacts arising from stents and calcium deposits. In the present approach first the bone structures are removed from the image so that these nearby high intensity regions do not interfere in the segmentation process. Next morphological operation is done on the bone-removed image to reduce the effect of streak artifacts. The order of these two operations can be inter-changed. Then, a manual contour is initialized on an axial slice of the pre-processed image and deformed and subsequently propagated to the consecutive slices for deformation. The snake process is governed by force field defined by intensity-based object-ness measure within a band defined by local image properties. The proposed algorithm has been tested on 7 CT images and compared with the ground truth obtained from manual segmentation by radiologist and accuracy between the range 93.16% to 85.08% is observed