title: Cerebral microhemorrhage.
abstract: OBJECTIVE
  With the advent of modern MRI imaging techniques, cerebral microhemorrhages have been increasingly recognized on gradient-echo (GE) or T2*-weighted MRI sequences in different populations. However, in clinical practice, their diagnostic value, associated risk, and prognostic significance are often unclear. This review summarizes the pathophysiology, differential diagnosis, epidemiology, and clinical significance of cerebral microhemorrhages.
  
  
  RESULTS
  Focal areas of signal loss on GE MRI imaging pathologically represent focal hemosiderin deposition associated with previous hemorrhagic events. Cerebral microhemorrhages have been noted in healthy elderly, ischemic cerebrovascular disease, intracerebral hemorrhage (ICH), cerebral amyloid angiopathy (CAA), and in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. Microhemorrhages have been associated with older age, hypertension, smoking, white matter disease, lacunar infarcts, previous ischemic stroke, or ICH. In CAA, microhemorrhages predict both the risk of recurrent lobar ICH and future clinical decline. In patients with ischemic cerebrovascular disease, microhemorrhage number and location may be associated with executive dysfunction and may predict the occurrence of ICH and lacunar infarction.
  
  
  CONCLUSIONS
  When cerebral microhemorrhages are diagnosed on MRI, conclusions regarding their significance and associated risks should be made based on the population examined. Further studies to characterize the associated risks of cerebral microhemorrhages in different stroke populations are needed to use this new imaging marker in therapeutic decisions.
authors.affiliation: Department of Neurology, CHU Lariboisière, Assistance Publique des Hôpitaux de Paris, France.
authors.forename: Anand
authors.initials: A
authors.lastname: Viswanathan
authors.forename: Hugues
authors.initials: H
authors.lastname: Chabriat
mesh_terms: D000368:Aged; D046589:CADASIL / Q000150:complications / Q000175:diagnosis; D016657:Cerebral Amyloid Angiopathy / Q000150:complications / Q000175:diagnosis; D005260:Female; D006801:Humans; D020300:Intracranial Hemorrhages / Q000175:diagnosis* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012306:Risk; D012307:Risk Factors; D020521:Stroke / Q000150:complications / Q000175:diagnosis; D013997:Time Factors; D016896:Treatment Outcome