OAK BROOK, Ill. -- Computed tomographic colonography (CTC) depictscancers and other clinically important conditions that would be missedwith standard colonoscopy and at very little additional cost, accordingto a study in the August issue of Radiology.
"The chance of finding cancer outside the colon may be assignificant as the chance of finding cancer inside the colon," saidJudy Yee, M.D., Chief of Radiology at the Veterans Affairs MedicalCenter and associate professor and Vice Chair of radiology atUniversity of California San Francisco School of Medicine.
CTC, also known as virtual colonoscopy, is a non-invasivescreening method for colon cancer. Virtual colonoscopy uses a series ofCT images to visually reconstruct the interior of the colon on acomputer. Unlike standard colonoscopy--which explores only the interiorof the colon, virtual colonoscopy depicts the surrounding areas aswell.
"Using the same amount of radiation as a non-contrast CT scan of theabdomen/pelvis, you can do a virtual colonoscopy and screen thesurrounding abdominal and pelvic area," Dr. Yee said.
To evaluate the prevalence of extracolonic findings at virtualcolonoscopy and to determine the cost of follow-up testing, Dr. Yee andcolleagues performed CTC on 500 men, including 194 (39 percent)considered average risk and 306 (61 percent) at high risk for coloncancer. The mean age of the men was 62.5. Of the 500 patients in thestudy, 315 (63 percent) had extracolonicfindings. Forty-five (9 percent) patients had clinically importantextracolonic findings.
Findings deemed clinically important included large aneurysms,suspicious lesions and masses in the solid organs of the abdomen,lymphadenopathy, pulmonary nodules and gallbladder wall thickening. Themean additional cost per CTC exam to work up the important findings was$28.12.
"The fact that the additional cost was so low indicates that thisprocedure is potentially cost effective, not only in regards to thecolonoscopy but for other conditions as well," Dr. Yee said.
Dr. Yee's research represents the longest follow-up (3.6 years)of patients after CTC and is one of the first to include average-riskpatients among the study cohort. There was no significant differencebetween the numbers of clinically important findings in average- andhigh-risk patients.
Radiology is a monthly scientific journal devoted to clinicalradiology and allied sciences. The journal is edited by Anthony V.Proto, M.D., School of Medicine, Virginia Commonwealth University,Richmond, Va. Radiology is owned and published by the RadiologicalSociety of North America, Inc. (RSNA.org/radiologyjnl)
The Radiological Society of North America (RSNA) is anassociation of more than 37,000 radiologists, radiation oncologists,medical physicists and related scientists committed to promotingexcellence in radiology through education and by fostering research,with the ultimate goal of improving patient care. The Society is basedin Oak Brook, Ill. (RSNA.org)
"Incidentally Discovered Extracolonic Abnormalities at CTColonography in a Male Population." Naveen N. Kumar, M.D., SuchitraGodara, M.B.B.S., Janice Casamina, M.D., Robert Hom, M.D., GregoryGaldino, M.D., Peter Dell, M.D., and Darice Liu, M.D., collaboratedwith Dr. Yee on this paper.
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