A method for examining the colon by taking a series of x-rays and then using a computer to reconstruct three-dimensional pictures (a CT scan) of the interior surfaces of the colon from these x-rays. The pictures can be saved, manipulated to better viewing angles, and reviewed after the procedure. The procedure requires a 48-hour low-fiber diet and a complete bowel cleansing. If something suspicious is noted, a regular colonoscopy is needed to biopsy or remove it. Virtual colonoscopy results in about 15% false positives (misleading readings that unnecessarily require a regular colonoscopy). It is also not yet known whether virtual colonoscopy can reliably detect flat adenomas which, like polyps, can give rise to colon cancer. Also called computed tomography or CT colography.
The ability of an agent of infection to produce disease. The virulence of a microorganism is a measure of the severity of the disease it causes.
A microorganism that is smaller than a bacterium that cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations); this ability to mutate is responsible for the ability of […]
- Virus, attenuated
a virus that is capable of stimulating an immune response and creating immunity but not of causing illness.
- Virus, human immunodeficiency (HIV)
The cause of AIDS. HIV has also been called the human lymphotropic virus type III, the lymphadenopathy-associated virus and the lymphadenopathy virus. No matter what name is applied, it is a retrovirus. (A retrovirus has an RNA genome and a reverse transcriptase enzyme. Using the reverse transcriptase, the virus uses its RNA as a template […]
- Virus, human lymphotropic, type III
Virus, human immunodeficiency.