Incidental findings common on brain MRI in adults

Clinical Question

How common are incidental brain findings in the general population?

Bottom Line

Incidental brain findings, especially asymptomatic brain infarcts, benign tumors, and aneurysms, are relatively common (> 10%) in a population of older adults. Having this information may lead to a beneficial intervention (for example, the repair of a 15-mm aneurysm) or it may worsen quality of life and increase healthcare costs (for example, by causing worry and repeat imaging for a small aneurysm or meningioma that is unlikely to become symptomatic). Longitudinal studies are needed to better delineate when we should worry and when we should reassure our patients. (LOE = 1b)


Vernooij MW, Ikram MA, Tanghe HL, et al. Incidental findings on brain MRI in the general population. N Engl J Med 2007;357(18):1821-1828.  [PMID:17978290]

Study Design







As our imaging technologies improve, we are increasingly faced with the problem of what to do when a patient's test shows an incidental finding. This study provides a baseline, telling us how common various brain findings are in a cross section of the population. Since 2005 the authors have performed a brain MRI on participants in the Rotterdam Study, a prospective cohort study of dementia. Almost all participants in the Rotterdam study agreed to imaging (91%). Participants had a mean age of 63 years (range = 45 years to 96 years) and 52% were women. Incidental findings were common, including: asymptomatic lacunar (5.6%) or cortical (2.0%) infarct; benign tumors (1.6%); aneurysms (1.8%); arachnoid cysts (1.1%); Chiari malformations Type I (0.9%); major vessel stenosis (0.5%); and cavernous angioma (0.4%). Malignancy or metastasis was rare, and was seen in only 2 patients. Infarcts and meningiomas became more common with age. Although aneurysms were relatively common, 32 of 35 were smaller than 7 mm and had a very low risk of rupture.