Open-source Software Increases Colon Polyp Conspicuity

Visibility of colon polyps is increased and sensitivity improved with the use of threshold-based color-coding software in virtual colonoscopy (also known as CT colonography or CTC), according to a new study from Italy. Even flat lesions were more often visible with use of the open-source 2D-based interpretation software.

Although low-dose CTC protocols with fecal tagging are effective for polyp detection, some smaller lesions -- and particularly flat polyps -- have been difficult to diagnose at CTC. Detection is even more challenging using mAs settings due to high image noise and the small CT density difference between the lesions and the colonic wall, said Dr. Lorenzo Faggioni from the University of Pisa in Italy.

To address this lack of conspicuity, some medical image processing applications, such as open-source OsiriX software (OsiriX, Geneva), generate color lookup tables (CLUT) that can enhance the contrast between lumen and wall of the colon, revealing CT density differences by means of color gradients (color coding), Faggioni explained in a presentation at the 2010 European Congress of Radiology (ECR).

Using the software's inverse thresholding function, CT values corresponding to colorectal polyps typically appear pink, tagging materials as violet, and the colonic mucosa a dark green.