Cerebral microbleeds: a magnetic resonance imaging review of common and less common causes.

Cerebral microbleeds (CMBs) are small foci of (acute, subacute or chronic) blood products, best seen using magnetic resonance imaging (MRI) techniques sensitive to iron deposits (i.e. gradient-echo T2*-weighted and susceptibility-weighted imaging), frequently encountered in small vessel disease (SVD) (with hypertensive vasculopathy and cerebral amyloid angiopathy as the most frequent conditions) and also in other disorders. In this review, the MRI characteristics of CMBs and the associated MRI abnormalities encountered in common and less common SVD and non-SVD conditions are the main focus. Identification of the origin of CMBs depends on their localization, the presence of other associated MRI abnormalities, and the patient's history and clinical state.