What’s CT Colonography
Patient Information
CT Colonography or Virtual colonoscopy is a new method that allows doctors to look at the large bowel (colon) to detect polyps and cancers. Polyps are small growths in the colon that may become cancerous if they are not removed. Virtual colonoscopy is a recently developed technique that uses a CT scanner and computer virtual reality software to look inside the body without having to insert a long tube (Conventional Colonoscopy) into the colon or without having to fill the colon with liquid barium (Barium Enema). Research performed at Boston University and elsewhere has shown that Virtual Colonoscopy is better able to see polyps than Barium Enema and is nearly as accurate as Conventional Colonoscopy. In addition, most patients report that the Virtual Colonoscopy technique is more comfortable than either Barium Enema or Conventional Colonoscopy.
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Why is it important?
Colorectal cancer (CRC) is a leading cause of cancer-related death in the world. Colon cancer can be prevented if polyps are discovered and removed early. Tumors, masses of abnormal cells, take years to develop. Initially, a cell from the colon starts to multiply abnormally and forms a benign (non-cancerous) polyp, which can remain harmless for a long time before becoming an aggressive cancer. Polyps, when detected, can be removed preventively. Nevertheless, individuals at greatest risk of developing colorectal cancer remain largely underscreened. This is due, in part, to poor public awareness and acceptance of current screening techniques.
How is Virtual Colonoscopy done?
Virtual colonoscopy uses a standard computed tomography (CT or CAT scan) of the abdomen, which allows radiologists (special physicians with advanced training in x-ray imaging) to create pictures on the computer that look similar to those seen by Conventional Colonoscopy. Patients need a cleansing preparation of their bowel prior to the test. The day of the test, they come to the radiology department for a CT scan. The actual virtual colonoscopy procedure will begin by having a small flexible rubber tube placed in the rectum, so that air can be introduced. A CAT scan is then performed while patients lie comfortably on their back and then on their stomach. The total time required for the study is approximately 10-20 minutes. Because sedation is not required, patients are free to leave the CT suite immediately without the need for observation or recovery. Patients can resume normal activities immediately after the procedure and can eat, work or drive without a delay. Doctors (radiologists) analyze the CT data to detect colon polyps or cancers.
Is it painful?
When air is introduced in the colon some patients experience minimal temporary abdominal cramping or "gas pains". An intravenous injection of a widely used medicine to relax the bowel can also be given to help reduce gas pains, but this is usually not necessary
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Images illustrations for Virtual colonoscopy: we can evaluate your colon and whole abdomen in the same time of scanning.
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Advantages:
· less invasive and safer with no perforation or sedation risks
· no sedation needed
· substantially lower cost
· offers complete colonic exam in patients with tortuosity or tumor that may prevent passage of a colonoscope
· can assess colonic wall thickness and structures outside the colonic lumen
Disadvantages:
· not entirely noninvasive - requires rectal tube and insufflation
· same cleansing prep as for colonoscopy
· inability to perform biopsy of suspicious findings at time of exam may require additional follow-up conventional colonoscopy
· less sensitivity for detection of very small polyps and superficial mucosal abnormalities than with colonoscopy
For more information, please contact BNH Imaging Centre, BNH Hospital
Tel. 02-686-2700 ext. 1114-1115 , 1119 Fax. 02-632-0579