Back in the 1940s, when plain old X rays were considered high tech, shoe salesclerks would often determine children's shoe size by X-raying their feet. Never mind that the same thing could have been done with a wooden ruler. Fluoroscopes, as the X-ray devices were called, were promoted as the scientific way to guarantee a proper fit. By the mid-1950s, however, it was clear that many fluoroscopes were badly maintained and ended up subjecting customers--not to mention salesclerks--to potentially dangerous amounts of radiation. Soon the machines were banned.
I was reminded of this bit of medical lore when I heard about the latest health craze in Southern California--full-body CT scans of otherwise healthy people. The goal is to find any budding tumors or other internal problems long before they would show up in a regular physical--and without exploratory surgery. Though this sounds like a good idea, in reality the same sort of technology envy that fueled the fluoroscope frenzy seems largely responsible for this latest craze as well. Only this time around, folks who get caught up in the hype could wind up losing peace of mind and a lot of money as well as damaging their health.
I'm not suggesting that today's multimillion dollar CT-scan machines are poorly maintained or that they routinely bathe you in excessive amounts of radiation. The issues are more subtle than that. We all have the sense that CT scans give you incredibly precise images that illuminate every nook and cranny of your body. But the truth is that CT scans, like MRIS, ultrasounds or other types of medical imaging, still require interpretation by radiologists who have trained for at least six years to figure out what those patches of light and dark mean. Otherwise, as Dr. Alec Megibow of New York University puts it, "we would have all been replaced by computers long ago."
Far from always providing definitive answers, CT scans often produce ambiguity, particularly when healthy people are subjected to them. Most of the time the scans turn up harmless stuff--a little scar tissue, a benign growth. But when they do, doctors have to perform more medical tests, frequently including invasive procedures, just to make sure that the spot is really harmless. "There certainly will be some people whose lives are saved [by the screening]," says Dr. Ron Arenson at the University of California, San Francisco. "But you have to weigh that against maybe thousands of patients who have had to undergo unnecessary procedures, each with its own attendant risks."
That is why most insurers and employers refuse to pay for whole-body CT scans for healthy people. So the "worried well" wind up paying $500 to $600 out of pocket for their imaging tests. Call me cynical, but in this era of managed care, I can't help noticing how that income stream also serves to pay for a lot of very expensive equipment. I'm more concerned, though, that some folks might consider a "clean" CT scan an excuse to forget about doing the things that we know improve health, like quitting smoking, shedding excess pounds or exercising more.
Still, there's no doubt that CT scans offer great potential as a screening tool. They're already providing useful snapshots of the coronary arteries, colon and lungs. Someday they may even replace more invasive tests. We're just not there yet.