Whole-body MRI screening

In people without symptoms, whole-body MRI finds confirmed cancer in about 1.6% of scans, pooled across 10 studies and 9,024 people [1]. It finds something much more often. In a review of 12 studies, about a third of people had a critical or uncertain finding, and where studies reported it, about 16% of findings turned out to be false alarms [2]. A larger review put potentially serious findings at about 4% of brain and body scans, half of them suspected cancers, rising to about 13% when uncertain findings were counted [3].

Those findings have consequences. In a German population study of 2,500 adults, 36% had a potentially relevant finding, and most were of unclear nature [4]. People who had the scan then spent about 12% more on outpatient care over two years than similar people who did not, mostly on more imaging and specialist visits [5].

No trial has tested whether screening healthy people this way prevents deaths, and none follows people long enough to count missed cancers. The American College of Radiology says there is no evidence that it is cost-efficient or prolongs life [6]. The case is different in people with inherited cancer risk: in carriers of a TP53 mutation (Li-Fraumeni syndrome), a first scan found new, treatable cancers in 7% [7]. A scan does not change how a body ages; any benefit would come from treating disease earlier.

• MRI uses no radiation, but most people screened have at least one finding, and checking harmless findings can lead to more scans, biopsies, cost and worry.
• A normal scan does not rule out cancer and does not replace recommended screening such as colonoscopy, mammography or cervical screening.
• People with pacemakers or other implanted devices, metal fragments or severe claustrophobia need to check with the clinic or a doctor before a scan.
• The American College of Radiology does not recommend whole-body screening for people without symptoms, risk factors or a family history of disease.
• Scans are usually paid out of pocket, from about $500 to several thousand dollars, and insurers rarely cover them or the follow-up of findings.