Clinical associations of cerebral microbleeds on magnetic resonance neuroimaging.

Susceptibility-weighted and gradient-recalled echo T2* magnetic resonance imaging have enabled the detection of very small foci of blood within the brain, which have been termed "cerebral microbleeds." These petechial intraparenchymal hemorrhages have begun to emerge as diagnostically and prognostically useful markers in a variety of disease states. Severe hypertension and cerebral amyloid angiopathy are perhaps the best established microhemorrhagic conditions from neuroimaging literature; however, many others are also recognized including cerebral autosomal dominant arteriopathy, subcortical infarcts, and leukoencephalopathy (CADASIL), moyamoya disease, fat embolism, cerebral malaria, and infective endocarditis. Microbleeds are also a common finding in the setting of trauma and stroke. The purpose of this review is to broadly describe the neuroimaging of cerebral microbleeds in a wide variety of conditions, including the differences in their appearance and distribution in different disease states. In a few situations, the presence of microbleeds may influence clinical management, and we discuss these situations in detail. The major importance of this emerging field in neuroimaging is the potential to identify microvascular pathology at an asymptomatic or minimally symptomatic stage and create a window of therapeutic opportunity.