Cheryl Weinstein's left knee bothered her for years, but when it started clicking and hurting when she straightened it, she told her internist that something was definitely wrong.
It was the start of her medical odyssey, a journey that led her to specialists, physical therapy, Internet searches and, finally, an M.R.I. scan that showed a torn cartilage and convinced her that her only hope for relief was to have surgery to repair it. But in fact, fixing the torn cartilage that was picked up on the scan was not going to solve her problem, which, eventually, she found was caused by arthritis.
Scans — more sensitive and easily available than ever — are increasingly finding abnormalities that may not be the cause of the problem for which they are blamed. It's an issue particularly for the millions of people who go to doctors' offices in pain.
The scans are expensive — Medicare and its beneficiaries pay about $750 to $950 for an M.R.I. scan of a knee or back, for example. Many doctors own their own scanners, which can provide an incentive to offer scans to their patients.
And so, in what is often an irresistible feedback loop, patients who are in pain often demand scans hoping to find out what is wrong, doctors are tempted to offer scans to those patients, and then, once a scan is done, it is common for doctors and patients to assume that any abnormalities found are the reason for the pain.
But in many cases it is just not known whether what is seen on a scan is the cause of the pain. The problem is that all too often, no one knows what is normal.
"A patient comes in because he's in pain," said Dr. Nelda Wray, a senior research scientist at the Methodist Institute for Technology in Houston. "We see something in a scan, and we assume causation. But we have no idea of the prevalence of the abnormality in routine populations."
Now, as more and more people have scans for everything from headaches to foot aches, more are left in a medical lurch, or with unnecessary or sometimes even harmful treatments, including surgery.