When doctors scan someone’s whole body for research, they sometimes find unexpected things — and more than half the time, they can’t tell if those things are harmless or dangerous without doing more tests.

When doctors scan healthy people’s whole bodies with MRI and find unexpected issues, most of those findings turn out to be important enough to check further—only about 1 in 10 are harmless.

When healthy people without symptoms get a full-body MRI scan, about 1 in 3 people end up with some unexpected finding on the scan — and almost 6 out of 10 of those surprises don’t clearly mean anything medically important.

Using a full-body MRI scan on people who feel fine can sometimes find hidden health problems they didn’t know they had—and some of those problems might need a doctor’s attention.

In a study where people got full-body MRI scans for research, about 1 in 3 were told they had some unexpected health finding that might need attention.

Getting a full-body MRI often finds weird little things that aren’t actually a problem, which can lead to more tests and stress — but we don’t yet know if all this causes more harm than good.