Virtual Colonoscopy (cont.)
Dennis Lee, MD
Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- What is colonoscopy?
- What is virtual colonoscopy?
- Comparing virtual colonoscopy and optical colonoscopy
- My personal approach to recommending virtual versus optical colonoscopies
What is virtual colonoscopy?
Virtual colonoscopy is a technique that uses a computerized tomographic (CT) scan (a type of three-dimensional x-ray) to construct virtual images of the colon that are similar to the views of the colon obtained by direct observation by optical colonoscopy.
In preparation for virtual colonoscopy, the day before the examination the colon is emptied using laxatives in a manner similar to optical colonoscopy. During the examination, a small tube is inserted into the anus to inject and fill the colon with air. Unlike with optical colonoscopy, this tube is not advanced into the colon. The CT scan then is performed, and the scans are manipulated by computer software to form virtual images of the colon. When properly performed, virtual colonoscopy can be as effective as optical colonoscopy. It can even find polyps "hiding" behind folds that occasionally are missed by optical colonoscopy. The scanning takes only 10 minutes, and usually no conscious sedation is necessary.
In October, 2007, researchers from University of Wisconsin published in the New England Journal of Medicine a study comparing traditional optical colonoscopy to virtual colonoscopy. More than six thousand patients over age 50 were evenly divided to undergo either optical or virtual colonoscopy. The researchers found that virtual colonoscopy was as effective as optical colonoscopy in detecting polyps larger than 5mm.
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