REDWOOD CITY, Calif., July 21 (San Francisco News Online) — A dramatic story about a brain tumor found during a preventive scan can make full-body MRI sound like an easy way to stay ahead of disease. But for most healthy adults, federal agencies and major medical groups still say the test should not be routine. Their concern is straightforward: the scan can find things, but it has not been shown to improve health enough to outweigh false alarms, extra testing and cost.
What a full-body MRI is
A full-body MRI uses magnetic fields to create images of many parts of the body at once. Unlike CT scans, MRI does not use ionizing radiation, the American Cancer Society says.
That difference is one reason the test can sound safer than other imaging. But the absence of radiation does not make it a proven screening tool for everyone. The Food and Drug Administration says it knows of no scientific evidence showing that scanning people without symptoms provides more benefit than harm.
Why doctors are cautious
The American College of Radiology says there is not enough evidence to recommend total-body screening for people who do not have symptoms, risk factors or a family history that points to disease. The American College of Preventive Medicine says doctors should not use whole-body scans for early tumor detection in people without symptoms of illness. The American Academy of Family Physicians also advises against routine use.
In San Francisco, UCSF radiology researcher Dr. Rebecca Smith-Bindman has warned that there is no evidence the scan helps people live longer or better.
What the scan can find — and why that can be a problem
Because a full-body MRI looks at so much of the body at once, it can turn up unexpected findings. The American Cancer Society says those may be harmless differences in normal anatomy, or they may be abnormalities that need more testing. The society describes some of these findings as “spots” or “shadows” that may turn out to be normal variation.
That is where the downside often starts. A suspicious-looking result can lead to more imaging, blood tests, biopsies or even surgery. Matthew Davenport, a radiologist at the University of Michigan, has said the harms come from invasive testing and follow-up of findings that are of uncertain benefit.
Those extra steps can also cause anxiety. The American Cancer Society lists false positives, incidental findings, unnecessary procedures, overdiagnosis and overtreatment among the main concerns. In overdiagnosis, a scan finds something that would never have caused symptoms or death but still leads to treatment.
Can the scan give false reassurance?
Yes. A normal result does not mean a person has no health problems. Cleveland Clinic says full-body MRI can miss disease and can produce false negatives.
That matters because a person may feel reassured by a clean scan and delay care for symptoms or problems that the test did not catch. For that reason, the scan is not a substitute for regular medical care or for screening tests that have already been studied and recommended for specific conditions.
What about cost?
The American Cancer Society says insurance companies rarely pay for full-body MRI because it is not part of standard medical care. That leaves many people to pay out of pocket for a test whose value is still uncertain.
The bottom line
For people without symptoms or specific risk factors, the message from the FDA, radiology groups and preventive-care experts is consistent: full-body MRI is not a routine screening test. It may find something important, but current evidence does not show that the scan improves outcomes enough to outweigh the chance of false alarms, follow-up tests and expense.
A single dramatic case can make the technology sound lifesaving. The broader medical question is different: whether scanning healthy people from head to toe actually helps more than it harms. So far, major medical groups say that answer has not been proven.
