REDWOOD CITY, Calif., July 21 (San Francisco News Online) — A preventive whole-body MRI can sound like a powerful safety check. A recent Fox News report about a former “Bachelor” contestant who said a scan found a brain tumor before symptoms started has pushed that idea back into the spotlight. But for most healthy adults, major medical groups say the scans are not routine screening tools, and the evidence has not shown that they improve health enough to outweigh the downsides.
That debate matters in San Francisco, where UCSF radiology researcher Dr. Rebecca Smith-Bindman has been among the clinicians warning that more scanning is not always better.
What is a full-body MRI?
A full-body MRI uses magnetic fields and radio waves to create images of many organs and tissues at once. Unlike CT scans, MRI does not use ionizing radiation, according to the American Cancer Society.
Companies that sell the scans promote them as a way to spot cancer, heart disease and other problems early. Prenuvo has said its scan can detect more than 500 conditions, including tumors at an early stage.
Why are doctors cautious?
The Food and Drug Administration says it knows of no scientific evidence that scanning people without symptoms offers more benefit than harm. The American College of Radiology says there is not enough evidence to recommend total-body screening for people with no symptoms, risk factors or family history suggesting serious disease.
Other medical groups have said the same in different ways. The American Academy of Family Physicians and the American College of Preventive Medicine advise against using whole-body scans for early tumor detection in people without symptoms. The U.S. Preventive Services Task Force has also given pancreatic cancer screening in asymptomatic adults who are not known to be high risk a D rating, meaning the harms outweigh the benefits.
The concern is not that MRI is dangerous in the way radiation can be. The concern is what happens after the scan.
What can go wrong?
The American Cancer Society says the biggest risk is the “downstream effects” of a scan that finds something unclear. Those findings can be harmless normal variations, but they may still lead to more imaging, biopsies, specialist visits and worry.
Doctors call these unexpected findings incidental findings or incidentalomas. They can trigger false positives, which means the scan looks suspicious even when nothing serious is wrong. They can also cause overdiagnosis, when a condition is found that would not have gone on to cause symptoms or death.
Dr. Rebecca Smith-Bindman told CBS San Francisco that there is “not a stitch of evidence” that the scan helps people live longer or better. She also warned that there could be large numbers of false positives and more testing that follows.
The American Cancer Society says a scan can also give false reassurance. A negative result does not guarantee that no disease is present.
Does catching something earlier always help?
Not necessarily. That is the heart of the debate.
A JAMA editorial by Matthew Davenport of the University of Michigan and Dr. Scott Reeder said no major medical group recommends whole-body MRI for the general population because the benefits are still unproven. Davenport has said the harms can come from invasive testing or surgery after findings that are of uncertain value.
In other words, a scan can find more. That does not always mean it helps more.
What about cost?
The American Cancer Society says insurance companies rarely pay for full-body MRI because it is not standard medical care. When people buy the scan on their own, they may face high out-of-pocket costs.
Should a healthy person get one?
For now, the answer from major medical groups is generally no, unless there is a specific medical reason or risk profile that changes the picture. The FDA, the American College of Radiology and other professional groups all say routine whole-body screening of people without symptoms has not been shown to provide enough benefit.
That is why the brain-tumor story has cut both ways. It shows why the scans are appealing. It also shows why doctors say a dramatic success story is not the same as proof that screening helps most people.
For Bay Area patients, the question is not just whether a scan can find something. It is whether finding more would truly improve health, or mostly create more uncertainty.
