Three-dimensional CT colonography

We have conducted research on three-dimensional (3D)-computed tomography (CT)-colonography with single and multi-slice helical CT scanning, a recent topic of special interest. CT provides multiple ways to detect colorectal neoplasia including standard axial CT, multiplanar reconstruction (MPR), and 3D-CT-colonography. Furthermore, 3D-CT-colonography offers several methods of visualization using volumetric CT data depending on the threshold setting of CT values. The flythrough system of virtual colonoscopy is worthy of note for computer-aided diagnosis (CAD). Virtual colonoscopy provides real-time endoscopic viewing that simulates fiber-optic endoscopy, by simply pointing at a location in the MPR view. Virtual colonoscopy makes it possible to advance confidently into the digestive tract, except for highly tortuous colons, to turn rapidly at the end of the digestive tract, and to return back along the tract. This method could potentially reduce non-visualized areas between haustra of the colon, but virtual colonoscopy sometimes has difficulty distinguishing polyps from feces. This problem is largely avoided by applying synthesized 3D and MPR images (3D-MPR-CT), which can provide information on the intraluminal orientation of focal abnormalities. Therefore, with progress in CAD, we believe that, combined with the fly-through system and 3D-MPR-CT, virtual colonoscopy might be applied in the future as first-line examinations in screening for colorectal neoplasia. (author)