Measurement of aortic calcification during computed-tomographic colonography (virtual colonoscopy) for colon cancer risk identifies patients at risk for myocardial infarction, according to a presentation at the annual meeting of the Radiological Society of North America (RSNA).

"This early study points to the possibility of multiple diagnostic benefits for patients participating in certain colon cancer screenings," said lead author and presenter Jesse A. Davila, MD.

Computed-tomographic colonography, or virtual colonoscopy, is a minimally invasive procedure that tests for colon cancer by creating two- and three-dimensional fly-through images that identify abnormalities such as precancerous polyps. Virtual colonoscopy requires no sedation and is less costly than conventional colonoscopy.

"With virtual colonoscopy providing a less invasive approach to diagnosing colon cancer, we wanted to measure whether additional information could be gained during the scan," Davila said. "Because cardiovascular disease is often asymptomatic prior to a major event, we hoped that we could use the scan to measure calcium deposit levels within the aorta and its branching vessels without the need for additional testing."

According to the Centers for Disease Control and Prevention, cardiovascular disease is the leading cause of death in the United States, followed closely by cancer. Colon cancer is the second leading cause of cancer deaths.

In the current study, researchers reviewed the records of 480 patients who received virtual colonoscopy exams at the Mayo Clinic in Rochester, Minn. from 1995 to 1998. Medical records showed a direct correlation between high aortic calcium scores measured during the procedure and the 9 patients who had myocardial infarctions subsequent to the screening.

By noting calcification scores during virtual colonoscopy procedures, physicians may have an additional means of identifying patients at risk for cardiovascular disease, according to Davila.

"While larger, follow-up studies are necessary to help verify our results, we hope that identifying the possible synergies in medical testing will encourage individuals to take advantage of the diagnostic tools available to them," Davila said. "As a leading cause of death, colon cancer should be identified as early as possible. The potential benefits from additional diagnostic uses for virtual colonoscopy should encourage individuals to undergo this very important procedure."