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Last reviewed and revised February 27, 2013
Wondering what to give that special someone who already has everything? How about an MRI test? In recent years, magnetic resonance imaging (MRI), other forms of whole-body scanning and sophisticated heart tests are being offered to anyone willing to pay the price. During the holiday season, they are being recommended as “stocking stuffers,” a unique gift to provide “peace of mind.” The technology that allows an MRI to provide pictures inside our bodies relies on the fact that the chemical building blocks of our organs respond to strong magnets. The atoms within our tissues “line up” when a strong magnet is applied, and when the magnetic field is released, the atoms “relax” and give rise to energy signals; a computer then interprets these signals into images of our anatomy. What was once unseen and impossible to evaluate short of surgery can now readily be measured, analyzed, and monitored over time. Among the most common and helpful applications of MRI is imaging of the brain, spine and spinal cord, knee, and organs of the abdomen and pelvis. At first glance, getting a peek inside the body before there are symptoms of trouble may seem like a good idea. However, the belief that “knowledge is power” is sometimes untrue, a medical myth that relies on intuition rather than facts. Although it is true that a normal MRI result could provide reassurance, there are several reasons to think twice about buying the test for someone (or for yourself):
Knowledge Is Power — Or Is It? I once cared for a patient who had fevers day after day without an identifiable reason; the usual and appropriate tests for infection and other common causes of fever were inconclusive or unhelpful. A medical student asked why we were not performing even more tests since, “after all, tests will give us more information and information is power.” It dawned on me then how that statement is only true if the information is good information. There are times when information is not power — in fact, bad information is often worse than no information at all. My patient turned out to have malaria — the key was ordering the right test, not ordering more tests simply because they're available. It is a statistical fact that for imperfect tests (which include almost all medical tests), screening large numbers of seemingly healthy persons will usually produce more false-positive results (abnormal results that turn out to be meaningless) than true-positive results (abnormal results that truly represent a disease). For this reason, it is best to understand the limitations of the test and try hard to prove that it provides benefit in excess of risk, before offering the test as a screen for reassurance or early detection of disease. That has not yet happened for screening MRIs. In recent years, companies that own expensive imaging instruments have begun to promote the tests directly to consumers. This is a new phenomenon — 20 years ago, you needed a good reason and an order from your doctor to have a CT (computed tomography) scan or even a regular X-ray. If you walked into your doctor’s office requesting a total body scan or other sophisticated imaging, your doctor probably would have explained how there was no reason to have the test and would not have ordered it. Now, in many locations, your own health-care provider can be bypassed. Perhaps it will turn out that this approach is useful and will lead to earlier disease detection, earlier treatment and better outcomes. For now, however, if you give someone an MRI test for the holidays and the results are not normal, they may have been better off with the gift of another sweater this year instead. Robert H. Shmerling, M.D., is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing primary-care physician and rheumatologist for 17 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.
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