Incidental findings on brain imaging are defined as previously undetected abnormalities of potential clinical relevance that are unexpectedly discovered and unrelated to the purpose of the imaging. Incidental findings are increasingly detected in clinical practice, with screening, and in the research setting. Data on the prevalence of these abnormalities are scarce, the clinical course of the findings is often unknown, and—as a result—the management of such lesions is not clear. As a community, we need to set standards on how to deal with such findings.

In the linked study (doi:10.1136/bmj.b3016), Morris and colleagues systematically reviewed the literature on incidental findings on brain magnetic resonance imaging (MRI) and found a prevalence of 0.7% (95% confidence interval 0.47% to 0.98%) for neoplastic lesions including meningeoma (0.3%), and 2.0% (1.1% to 3.1%) for non-neoplastic lesions including aneurysms (0.4%).1 The authors state that they have increased the precision of existing estimates on the prevalence of incidental findings.

However, the findings have merely touched the tip of the iceberg. The 16 included studies were published between 1989 and 2008, and the incidental findings were detected on scanners with different field strengths and using …