CT colonography can screen for both colorectal cancer and osteoporosis reliably at minimal additional cost and time, according to a study at San Francisco VA Hospital.
Given the nature of CT colonography, radiologists may construct scans into 3D models of the spine, which can then be used to measure bone mineral density, according to lead author of the study Dr. Rizwan Aslam, an assistant clinical professor of radiology at the University of California, San Francisco. Radiologists can then use the information to determine the risk or presence of osteoporosis.
"We wanted to look at the ability of CT to not only screen for colon cancer but also allow identification of patients with osteoporosis, and we thought we could crack both of them with this test," Aslam said.
The retrospective study compared dual x-ray absorptiometry (DXA) scores with CT colonography results in 30 men and five women ranging in age from 54 to 79. All CT scans were performed on a 16-slice scanner.
Results showed excellent agreement between the DXA bone mineral density scores and the data obtained through the CT colonography study. The researchers found a correlation of 0.41 and 0.39 for the CT and DXA BMD readings per vertebral body level and 0.5 and 0.51 for the CT and DXA T-score per vertebral body. The ability to perform colonography and bone densitometry simultaneously could be especially valuable because colon cancer and osteoporosis both affect adults older than 50. Doubling up the exams also means avoiding radiation exposure from a second scan.
"Virtual colonoscopy can successfully evaluate patients for osteoporosis, and colonoscopy provides valuable information on osteoporosis risk with no additional radiation or cost," Aslam said.