An integrated electronic colon cleansing for CT colonoscopy via MAP-EM segmentation and scale-based scatter correction

Orally administered tagging agents are usually used in CT colonography (CTC) to differentiate residual bowel content from native colonic structure. However, the high-density contrast agents tend to introduce the scatter effect on neighboring soft tissues and elevate their observed CT attenuation values toward that of the tagged materials (TMs), which may result in an excessive electronic colon cleansing (ECC) where pseudo-enhanced soft tissues are incorrectly identified as TMs. To address this issue, we integrated a scale-based scatter correction as a preprocessing procedure into our previous ECC pipeline based on the maximum a posteriori expectation-maximization (MAP-EM) partial volume segmentation. The newly proposed ECC scheme takes into account both scatter effect and partial volume effect that commonly appear in CTC images. We evaluated the new method with 10 patient CTC studies and found improved performance. Our results suggest that the proposed strategy is effective with potentially significant benefits for both clinical CTC examinations and automatic computer-aided detection (CAD) of colon polyps.