Is virtual colonography useful in the diagnosis or management of inflammatory bowel diseases?

Abstract

V irtual endoscopy is an image postprocessing technique that basically employs sectional volume image data like spiral computed tomography (CT) or magnetic resonance imaging (MRI) for creating virtual 3D models of the colon. Compared to the MRI-based technique the CT-based approach represents a more robust and faster imaging process. The major drawback of CT colonography is exposure to ionizing radiation, the effective dose varying from 0.5–12 mSV.1 MRI colonography reveals superior soft tissue resolution combined with the advantage of a total lack of ionizing radiation, which is a major argument for the mostly young patients with inflammatory bowel disease (IBD). The majority of the data concerning the sensitivity and specificity of virtual colonography in comparison to conventional colonoscopy were generated using the CT technique as a new method of screening for colorectal cancer. A meta-analysis of 33 studies with over 6000 patients demonstrated a heterogeneous sensitivity of polyp detection by CT-colonography ranging from 48%–85%, which improved as polyp size increased.2 However, more recently with more advanced hardand software applications a better sensitivity and specificity especially for polyp sizes 6 mm are reported.3