Imaging tests are also used to screen for and detect colorectal cancer. These tests use technologies that visualize your body organs and present them like a picture. Imaging tests are also used to determine how far the cancer has spread or how well it is responding, or has responded, to treatment. While some tests still use X-rays, newer technologies use radioactivity (in very tiny doses), ultrasound, or magnetic fields to obtain the pictures.
The imaging test for the initial detection of colorectal cancer is virtual colonoscopy.
Colonoscopy (koh-luh-NAH-skuh-pee) lets the physician look inside your entire large intestine, from the lowest part, the rectum, all the way up through the colon to the lower end of the small intestine. The procedure is used to diagnose the causes of unexplained blood in the stool or changes in bowel habits. It is also used to look for early signs of cancer in the colon and rectum. Colonoscopy enables the physician to see inflamed tissue, abnormal growths, ulcers, bleeding, and muscle spasms...
New technology has made it possible for a computer to take CT images of the colon and reconstruct a three-dimensional model of your colon. The inside of this model can be inspected, without causing any pain to you, to search for abnormalities. The test involves enlargement or distension of the colon with air. Early results show promise for screening the colon and detecting small polyps or asymptomatic colorectal cancers.
The main disadvantage of virtual colonoscopy is that any abnormalities have to be evaluated and treated by real-time colonoscopy. However, it is likely to have a place in screening for colorectal cancer.