This paper presents a digital bowel cleansing (DBC) free detection method of colonic polyp from fecal tagging CT images. Virtual colonoscopy (VC) or CT colonography is a new colon diagnostic method to examine the inside of the colon. However, since the colon has many haustra and its shape is long and convoluted, there is a risk of overlooking of lesions existing in blinded areas caused by haustra. Automated polyp detection from colonic CT images will reduce the risk of overlooking. Although many methods for polyp detection have been proposed, these methods needed DBC to detect polyps surrounded by tagged fecal material (TFM). However, DBC may changes shapes of polyps or haustra while removing TFM and it adversely affect polyp detection. We propose a colonic polyp detection method that enables us to detect polyps surrounded by either the air or the TFM simultaneously without any DBC processes. CT values inside polyps surrounded by the air and polyps surrounded by the TFM regions tend to gradually increase (blob structure) and decrease (inverse-blob structure) from outward to inward, respectively. We thus employ blob and inverse-blob structure enhancement filters based on the eigenvalues of the Hessian matrix to detect polyps using intensity characteristic of polyps. False positive elimination is performed using three feature values: the volume, maximum value of the filter outputs, and the standard deviation of CT values inside polyp candidate regions. We applied the proposed method to 104 cases of abdominal CT images. Sensitivity for polyps ≥ 6 mm was 91.2% with 7.8 FPs/case.

Date Published: 27 March 2008
PDF: 10 pages
Proc. SPIE 6915, Medical Imaging 2008: Computer-Aided Diagnosis, 69152H (27 March 2008); doi: 10.1117/12.771580

Published in SPIE Proceedings Vol. 6915:
Medical Imaging 2008: Computer-Aided Diagnosis
Maryellen L. Giger; Nico Karssemeijer, Editor(s)