title: Silent cerebral microbleeds on T2*-weighted MRI: correlation with stroke subtype, stroke recurrence, and leukoaraiosis.
abstract: OBJECTIVE
  Gradient-echo T2*-weighted MRI is uniquely sensitive to detect silent, old hemosiderin deposits, but the clinical significance of such "microbleeds" remains to be determined. Therefore, we investigated the incidence and the number of microbleeds among different stroke subtypes and the correlation with stroke recurrence and the severity of leukoaraiosis.
  
  
  METHODS
  This study consisted of 213 patients (73.5+/-9.1 years old, 104 men and 109 women), who were classified according to stroke subtypes into atherothrombotic infarction (24 patients), cardioembolic infarction (23 patients), lacunar infarction (66 patients), intracerebral hemorrhage (35 patients), and control (65 patients) groups. Gradient-echo T2*-weighted MRI was performed with a 1.5 T system, and asymptomatic microbleeds were located and counted.
  
  
  RESULTS
  The incidence and the number of microbleeds were significantly greater in patients with intracerebral hemorrhage (71.4% and 9.1+/-13.8, respectively) and lacunar infarction (62.1% and 7.4+/-16.1) compared with patients with cardioembolic infarction (30.4% and 2.5+/-5.6), atherothrombotic infarction (20.8% and 0.63+/-1.53), and controls (7.7% and 0.09+/-0.34). There was a correlation between the number of microbleeds and the severity of periventricular hyperintensity (r=0.626, P<0.0001). There was also a correlation between the number of microbleeds and the number of intracerebral hemorrhages (r=0.689, P<0.0001) or lacunar infarctions (r=0.514, P<0.0001). The locations of microbleeds were subcortical white matter (31.8%), thalamus (24.8%), basal ganglia (19.8%), brain stem (12.0%), and cerebellum (11.7%).
  
  
  CONCLUSIONS
  The findings suggest that microbleeds on T2*-weighted MRI are an indicator of advanced small artery disease of the brain with an increased risk for bleeding. This result should be taken into consideration when treating patients with stroke, and further studies are required.
authors.affiliation: Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan. katoh@mail.cc.tohoku.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kato
authors.forename: Masahiro
authors.initials: M
authors.lastname: Izumiyama
authors.forename: Kimiaki
authors.initials: K
authors.lastname: Izumiyama
authors.forename: Akira
authors.initials: A
authors.lastname: Takahashi
authors.forename: Yasuto
authors.initials: Y
authors.lastname: Itoyama
mesh_terms: D000368:Aged; D001921:Brain / Q000098:blood supply; D002544:Cerebral Infarction / Q000150:complications / Q000175:diagnosis; D005260:Female; D006485:Hemosiderin; D006801:Humans; D020300:Intracranial Hemorrhages / Q000150:complications / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008833:Microcirculation; D011237:Predictive Value of Tests; D012008:Recurrence; D020521:Stroke / Q000145:classification* / Q000150:complications / Q000175:diagnosis*
chemical_list: D006485:Hemosiderin