Virtual Dissection and Automated Polyp Detection of the Colon Based on Spiral CT - Techniques and Preliminary Experience on a Cadaveric Phantom

Abstract

Summary: Background: CT colonography was found to be sensitive and specific for detection of colonic polyps and colorectal cancer (CRC). Depending on the software used, CT colonography requires a certain amount of operator interaction, which limits it's widespread usage. The goal of this papers is to present two novel automated techniques for displaying CT colonography: virtual dissection and automated colonic polyp detection. Methods: Virtual dissection refers to a technique where the entire colon is virtually stretched and flattened thus simulating the view on the pathologist's table. Colonic folds show a ‘global outward bulging of the contour’, whereas colonic polyps exhibit the inverse (‘local inward bulging’). This feature is used to map areas of ‘local inward bulging’ with colours on 3D reconstructions. A cadaveric phantom with 13 artificially inserted polyps was used for validation of both techniques. Results: On virtual dissection all 13 inserted polyps could be identified. They appeared either as bumps or as local broadening of colonic folds. In addition, the automated colonic polyp detection algorithm was able to tag all polyps. Only 10 min of operator interaction were necessary for both techniques. Conclusions: Virtual dissection overcomes the shortcomings of CT colonography, and automated colonic polyp detection establishes a roadmap of the polyps.

Invited Commentary to: 'Virtual Dissection and Automated Polyp Detection of the Colon Based on Spiral CT - Techniques and Prelim inary Experience on a Cadaveric Phantom' (Eur. Surg. 2002;34:143 - 149)

“…This development is continued with the present paper by Sorantin et al (5). It presents two novel automated techniques for display of CT colonography: virtual dissection and automated colonic polyp detection.…”

“…In our opinion there are no advantages of virtual versus conventional colonoscopy: for both procedures accurate bowel cleansing is crucial (2), the entire colon has to be distended by air insufflation (2), and the risk of perforation is almost equal. According to Sorantin et al, the risk of perforation of virtual colonoscopy is between 0.06 % and 0.1 % (5). In three large series of diagnostic conventional colonoscopies, it was also between 0.06 % and 0.1 % (3, 6, 7).…”

Comparison of 64-Detector CT Colonography and Conventional Colonoscopy in the Detection of Colorectal Lesions

“…Today, new software algorithms that have been developed are replacing the traditional 2D and 3D endoluminal images. Virtual gross pathological imaging (virtual gross dissection) allows visualization of the colon on the long axis, so that flat lesions can be viewed in a tubular form as in actual pathological preparations ( 27 , 28 ). Computer-aided detection systems (CAD) automatically detect polyps and masses in CT images.…”