Evidence-based clinical indications for CT colonography in Japan

Abstract

The purpose of this evidence-based review was to evaluate the current status of the performance of CT colonography and clinical indications in Japan. Japanese National CT Colonography Trial and UMIN6665 study revealed that the accuracy of the detection of colorectal neoplasia was as high as colonoscopy performed by board-certified colonoscopists. Interpretation by gastroenterologists and radiologists was accurate for the detection of polypoid neoplasms, but less so for nonpolypoid neoplasms. UMIN9278 study showed low-dose CTC with iterative reconstruction reduced the radiation dose by 75% (mean effective radiation exposure, 0.46mSv) without image quality degradation compared to routine-dose CTC with filtered back projection. UMIN9278 study revealed colonic distention was significantly improved by automated carbon dioxide insufflation, but not by the administration of hyoscine butylbromide. When colonoscopy is contraindicated or not possible, CT colonography is an acceptable and equally sensitive alternative for patients as a diagnostic test for colorectal neoplasia. The combination of sigmoidoscopy and barium enema is also acceptable.