More importantly, virtual colonoscopy identified every patient with clinically significant polyps, Dr. Yee said. Once a potentially problematic lesion is identified by virtual colonoscopy, a patient must undergo a standard colonoscopy. During this exam a biopsy may be performed to give a clearer picture of whether or not the polyps might be cancerous, Dr. Yee said. In addition to its effectiveness at discovering colon cancer, virtual colonoscopy can also detect diseases and problems in other organs. The CT scan creates an image of the entire lower abdominal area, so radiologists can find problems such as kidney cancer, aneurysms in the aorta, and even lung cancers near the bottom of the lungs.
Virtual colonoscopy is also faster for the patient than traditional screening.
Whereas standard colonoscopy can take between 30 minutes to one hour, not including time required to recover from sedatives, the CT scan takes roughly a minute to perform, Dr. Yee said. Once collected, the data is transmitted via fiber-optic cable to a workstation equipped with specialized analysis software, which can create 3D images of the interior surface of the colon, and highlight some of the parts of the colon where a polyp is likely to exist. The radiologist can rotate the images, zoom in and out, and even create movie loops that look like a trip through the inside of the colon. But the time required for analysis is one of the major drawbacks for virtual colonoscopy, Dr. Yee said. This work is funded by the National Institutes of Health.