title: Microembolic signals within 24 hours of stroke onset and diffusion-weighted MRI abnormalities.
abstract: BACKGROUND
  The clinical relevance of the microembolic signals (MES) detected by transcranial Doppler sonography (TCD) in acute stroke remains unclear. In a prospective study the authors analyzed the relationship between MES and the findings on diffusion-weighted magnetic resonance imaging (DWI) in acute stroke patients.
  
  
  METHODS
  We performed TCD for a period of 30 min to detect MES in patients within 24 h of stroke onset, and DWI was done within the initial 7 days. MES were assessed from Doppler waves obtained from the middle cerebral artery contralateral to the side of the neurological deficits. The acute ischemic lesions observed on DWI were classified by their diameter (small, medium or large) and by their site (cortical, superficial perforator territory, internal borderzone or deep perforator territory).
  
  
  RESULTS
  We obtained Doppler waves from 39 vessels in 37 patients; 2 patients had bilateral deficits. MES were detected in 12 vessels (MES-positive group) and not detected in 27 vessels (MES-negative group). No significant differences in clinical features were observed between the 2 groups. The number of small lesions was significantly higher in the MES-positive group than in the MES-negative group (p = 0.02). The numbers of cortical and superficial perforator infarcts were significantly higher in the MES-positive group than in the MES-negative group (p = 0.002 and 0.02, respectively).
  
  
  CONCLUSIONS
  In acute ischemic stroke, MES detected by TCD in the acute phase may produce small cortical and subcortical lesions found on DWI.
authors.affiliation: Cerebrovascular Division, Department of Medicine, National Cardiovascular Center, Osaka, Japan. rosainakazima@ybb.ne.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakajima
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kimura
authors.forename: Atsuko
authors.initials: A
authors.lastname: Shimode
authors.forename: Fumio
authors.initials: F
authors.lastname: Miyashita
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchino
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Naritomi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Minematsu
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000150:complications / Q000175:diagnosis / Q000209:etiology / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D020766:Intracranial Embolism / Q000150:complications / Q000175:diagnosis / Q000473:pathology*; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000209:etiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000473:pathology*; D011446:Prospective Studies; D020521:Stroke / Q000175:diagnosis / Q000209:etiology / Q000473:pathology*; D013687:Telencephalon / Q000473:pathology; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial