If a whole-body MRI scan comes back negative, there’s a 99.8% chance you don’t have any new cancer developing in the short term—especially if you didn’t need a biopsy after the scan.

If a child gets a whole-body MRI and it comes back negative, there’s a 99.1% chance they don’t have cancer — so doctors can be very confident the child is cancer-free based on this scan.

When people got a full-body MRI scan and then had a biopsy done just to check if something was wrong, more than half of them turned out to have cancer — so the biopsy seems to be a good way to find real cancer cases in this group.

If you have Li-Fraumeni syndrome and get a whole-body MRI that shows no cancer, there’s a 97.4% chance you really don’t have any right now — but it doesn’t mean you won’t get cancer before your next scan.

If you get a full-body MRI scan and have no symptoms or known cancer risks, about 1 in 60 people might be found to have cancer they didn’t know about — so it’s kind of helpful, but not super reliable, for finding hidden cancers in healthy people.

When doctors use whole-body MRI scans on people who feel fine and aren’t sick, they find cancer in only about 1.57 out of every 100 people — so it’s not very good at catching cancer early in healthy folks.