REDWOOD CITY, Calif., July 21 (San Francisco News Online) — A preventive scan that found a brain tumor in a former “Bachelor” contestant has put full-body MRI screenings back in the spotlight, but the broader medical debate is less about rare success stories and more about what the scans mean for ordinary people who feel fine.
For most healthy adults, major medical groups and federal regulators say full-body MRI screening is not recommended. The Food and Drug Administration says it knows of no scientific evidence showing that scanning people without symptoms does more good 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 disease. The American Academy of Family Physicians and the American College of Preventive Medicine also advise against using whole-body scans to look for early tumors in people without symptoms.
What is a full-body MRI?
A full-body MRI is a magnetic resonance scan that images large parts of the body in one session. Unlike CT scans, MRI does not use ionizing radiation. That difference matters because one reason some people seek out whole-body MRI is to avoid repeated radiation exposure from other kinds of scans.
Companies that sell the scans often market them as a way to find disease early. In a recent CBS San Francisco report, Prenuvo said its scan can detect more than 500 conditions, including cancers at an early stage. But UCSF radiology researcher Dr. Rebecca Smith-Bindman told CBS San Francisco that there is not proof the scans help people live longer or better, and she warned that false positives can set off more testing.
Why are doctors cautious?
The biggest concern is not that MRI cannot find anything. It can. The concern is that it often finds things that are not dangerous, not related to symptoms, or not even clearly understood.
The American Cancer Society says the risk comes from the downstream effects: a scan may show spots or shadows that turn out to be normal variation, but still lead to follow-up tests, biopsies, procedures and anxiety. It also says whole-body scans can create false reassurance if they miss a problem that is already there but too small or subtle to see.
That is why the FDA says the core question is not whether a scan can produce images, but whether those images improve health outcomes. Right now, the agency says it knows of no scientific evidence that whole-body screening of people without symptoms provides more benefit than harm.
The evidence gap shows up in professional guidance too. In an April 2023 statement, the American College of Radiology said there is insufficient evidence to justify recommending total-body screening for people with no clinical symptoms, risk factors or relevant family history. A JAMA editorial discussed by ABC News said no major medical group recommends whole-body MRI for the general population because the benefits remain unproven.
What can happen after an abnormal result?
An abnormal result does not always mean cancer. It can mean a benign cyst, a harmless spot, or a finding that is too vague to interpret right away. Medical reviews summarized by professional publications say that incidental findings — sometimes called incidentalomas — are common enough to create a chain reaction of more imaging and tests.
That chain reaction is one reason experts worry about overdiagnosis, which means finding a condition that would never have caused symptoms or death. It can also lead to overtreatment, meaning treatment that was not needed in the first place.
Dr. Matthew Davenport, a University of Michigan radiology professor and urology professor, told ABC News that the harms come from invasive testing, surgery or follow-up of findings whose benefit is uncertain. Cleveland Clinic similarly warns that full-body MRI can uncover abnormalities that may never matter, while also missing some disease.
Do the scans ever help?
Yes, in some people with symptoms or a specific risk profile, imaging can be useful. The controversy is about screening large numbers of people who do not have symptoms and are not known to be at high risk.
The U.S. Preventive Services Task Force gives pancreatic cancer screening in asymptomatic adults who are not known to be at high risk a D rating, meaning harms outweigh benefits. That does not mean every MRI is unnecessary. It means broad screening of healthy people is not supported the way some companies suggest.
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 means people who choose the scan often pay out of pocket.
For Bay Area readers, the local debate has a familiar face: UCSF. Dr. Smith-Bindman, who works in San Francisco, has been one of the clearest local critics of the trend. In CBS San Francisco’s coverage, she said there is no evidence the scans prolong life or improve outcomes and warned about the risk of false positives.
Why the debate keeps coming back
The appeal of a full-body MRI is easy to understand: one scan, one answer, maybe a hidden problem caught early. But the medical groups weighing in say the tradeoff is uncertain. A scan can uncover something important, yet it can also trigger a cascade of worry and medical follow-up without proving that a healthier life will follow.
That is why the current debate is less about whether MRI can see the body and more about whether seeing more leads to better care. For now, the FDA and major medical organizations say that question remains unanswered for people without symptoms.
