Is a full-body MRI scan useful as a preventive measure?
For healthy people without an elevated hereditary risk a preventive full-body MRI is not useful: the chance of unnecessary follow-up investigations is high, and evidence of genuine health benefit is lacking. If you do have a proven hereditary cancer risk, such a scan is in fact recommended.
A full-body MRI sounds appealing: one scan, the entire body in view. But for healthy people without a specifically elevated risk there is no evidence that this is useful. Added value, reliability and cost-effectiveness have not been demonstrated for the general population1.
The problem is not that the scan finds too little, but rather too much -- and that rarely works out well. A meta-analysis of 12 studies (5,373 participants) found that roughly one third of healthy participants had a critical or unclear finding. A substantial proportion turned out to be false-positive: 16% on average, but with an uncertainty range of 1.9% to 65.8%. Long-term data of five years or more on a negative result are entirely absent2.
A second review of 12 studies (6,214 scans) confirms this. Almost everyone -- 95% of participants -- had at least one abnormal finding. In 30% of cases further investigation was needed, yet in the end cancer was actually confirmed in only 1.1%3. A study of 576 people without symptoms paints a slightly more nuanced picture: in 11.2% the scan led to a treatment, and cancers (2.6%) and brain aneurysms (bulges in blood vessels in the head, 4.8%) were detected. At the same time the scan missed relevant findings in 2.8% of participants, including five cancer patients. For colorectal, thyroid and breast cancer the scan proved to have limited suitability4.
There is one group for whom a full-body MRI does clearly offer added value: people with a proven hereditary elevated cancer risk. For them a broad recommendation applies, both for adults and children with such a predisposition5,3. The scan is also a recognised tool in a known condition such as multiple myeloma6. That is something fundamentally different from preventive scanning in healthy people.
Finally: how satisfied you are with the scan says little about its medical value. People who have high expectations of its usefulness are more satisfied with the outcome -- as shown by a small study of 154 people7. That helps explain why people can experience such a scan as worthwhile, even when science does not support that for most people.
Based on two systematic reviews with meta-analyses, one retrospective cohort study and multiple guideline and review publications (together covering more than 11,000 scanned individuals in the quantitative studies). The studies vary considerably among themselves and include no randomised trials examining long-term health outcomes.