November 2001 • POST-ASSEMBLY EDITION
Do total body scans have clinical value?
One ad reads, "What you don't know may be killing you." Another says, "It's easy, fast and painless. It's really fun."
These are not ads for a health lecture or an aerobic exercise program. Instead, they're campaigns promoting total body computed tomography scanning as a screening tool for disease.
"Are media hype and the profit motive getting ahead of the curve of what we know about the science of screening?" asked family physician Mark Needham, M.D., in his Oct. 5 lecture on total body scans at the Scientific Assembly. Needham, in private practice with the Santa Monica Bay Physicians in Santa Monica, Calif., talked about the proliferation of commercial centers dedicated to total body scans. He has a special interest in radiology and has been teaching family practice residents and family physicians about advanced imaging for several years.
The scanning centers, called "stores" in the industry, are slowly becoming popular additions to malls across the country because there's a lot of money to be made from them. Aging baby boomers are increasingly concerned about their health, and most Americans just love technology, Needham said.
But is there any clinical value to body scanning? Controlled, randomized trials are needed to answer that question definitively -- and some are now under way for various human organ systems. The currently available scientific evidence, however, shows mixed results.
Needham described what is known about the clinical value of electron-beam CT and spiral CT scanning in various organs and body areas.
- Brain. "There is no clinical benefit in asymptomatic people," he said. Magnetic resonance imaging and magnetic resonance angiography are better methods to detect potential problems in those patients, according to Needham.
- Lungs. Body scanning is a promising technique in lung cancer screening, Needham said, but it results in many false positives that require long-term follow-up studies. One of the major criticisms of total body scanning is that it generates additional studies for false positives that drive up the cost of health care, he added. Also, more invasive testing may create unnecessary risks for patients.
- Heart. CT scanning is useful in detecting coronary artery calcification, the hardened plaque that often underlies coronary artery disease. "I think CT body scanning has its greatest clinical utility in assessing the risk of coronary artery disease," Needham said. One drawback, however, is that it does not detect soft plaque, which can also cause coronary events, such as heart attacks, as it builds up in the arteries. Manufacturers are currently developing scanners that will detect soft plaque as well, he said.
- Bone.CT scanning is useful in determining bone density in the spine, Needham said, but there are better alternatives available, such as the dual energy X-ray absorptiometry test.
- Abdomen and pelvis. Body scans are not indicated in screening for disease in the abdomen and pelvis because they have a low yield and produce many false positives, Needham noted.
- Colon. Finally, Needham said, virtual CT colonoscopy is a promising technique, compared with conventional colonoscopy, in detecting larger polyps. "In fact, conventional colonoscopy fails to reach the cecum 5 percent of the time, so virtual colonoscopy may actually be superior," he said.
FP Report is published by the AAFP News Department.
Copyright © 2001 by American Academy of Family Physicians.
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