Japanese National Computed Tomographic (CT) Colonography Trial

The investigators will evaluate the sensitivity of CTC in detecting colorectal polyps and cancers (at least 6 mm in diameter) in 1,500 subjects at increased risk of colorectal cancer (CRC), using optical colonoscopy as the reference standard. The primary endpoint will be sensitivity in the detection of colorectal polyps and cancers that are at least 6 mm in diameter. The secondary endpoints will include specificity and predictive values in the detection of colorectal polyps and cancers. This clinical study will also evaluate the differences of the detection accuracies between human readings with and without computer-aided detection (CAD) that automatically detects colonic lesions in CTC images and presents the detected lesions to the readers. This clinical study will also compare performance between radiologists and gastroenterologists in detecting colorectal lesions in CTC images. All the CTC images and their interpretations, optical colonoscopy reports and images, and pathology reports of resected colorectal lesion will be prospectively collected from 12 Japanese hospitals participating in the trial. All patients' information will be completely anonymized at each site before any analysis of the data takes place.