Silent cerebral microbleeds on susceptibility-weighted imaging of patients with ischemic stroke and leukoaraiosis.

OBJECTIVE: Cerebral microbleeds (CMBs) are an increasingly recognized in patients with cerebrovascular disease who undergo the new MRI techniques. Susceptibility-weighted MRI is sensitive to detect silent microbleeds which are associated with microangiopathy from atherosclerosis, amyloid angiopathy or asymptomatic elderly individuals. CMBs are intracerebral old hemosiderin deposits in the perivascular space, and the clinical significance of such 'microbleeds' remains controversy. We investigated the incidence of microbleeds among different ischemic stroke subtypes and the severity of leukoaraiosis.
METHODS: In this study, we collected 137 patients (73.5 +/- 9.1 years old, 84 men and 53 women) who were divided into five groups: atherothrombotic infarction (34 patients), cardioembolic infarction (24 patients), lacunar infarction (35 patients), other determined or undetermined infarction (21 patients) and control (23 patients), in which 52 had primary stroke and 62 had recurrent stroke. Microbleeds were counted and leukoaraiosis was graded using susceptibility-weighted, T1-, T2- and FLAIR MRI with a 3.0 T system.
RESULTS: Microbleeds were high in lacunar infarction (25.7%) and atherothrombotic infarction patients (20.6%). Microbleeds were low in patients with cardioembolic infarction (4.2%). Both microbleeds (> or =grade 2) and leukoaraiosis in severity (> or =grade 2) were higher in the recurrent stroke group (14.5 and 48.4%) than those in the primary stroke group (3.8 and 7.7%). Leukoaraiosis (r=0.803, p<0.05) and recurrent stroke (r=0.708, p<0.05) were significantly associated with microbleeds.
CONCLUSIONS: Asymptomatic CMBs are observed with a markedly higher frequency in recurrent stroke, and are closely associated with the severity of leukoaraiosis.