title: Rapid appearance of new cerebral microbleeds after acute ischemic stroke.
abstract: BACKGROUND
  It is unknown whether the development of cerebral microbleeds (MBs), small areas of signal loss on T2*-weighted gradient-echo imaging (GRE), follows a slow or a rapid process. We hypothesized that MBs may develop rapidly after certain critical events, such as strokes, and investigated the frequency, location, and factors associated with the formation of new MBs after acute ischemic stroke.
  
  
  METHODS
  We retrospectively examined 237 consecutive acute ischemic stroke patients who underwent MRI within 24 hours and follow-up MRI during the week after symptom onset. We defined new MBs as MBs that newly appeared on follow-up GRE outside the infarcted area. We examined the association of new MBs with demographics, risk factors, laboratory data, baseline MBs, and small vessel disease (SVD; leukoaraiosis and lacunar infarctions).
  
  
  RESULTS
  Seventy-five patients (31.6%) had baseline MBs, and 30 (12.7%) developed new MBs. Multiple logistic regression analysis indicated that the presence of baseline MBs (odds ratio [OR] 5.72, 95% confidence interval [CI] 2.12-15.42, p = 0.001) and severe SVD (OR 2.94, 95% CI 1.12-7.77, p = 0.03) independently predicted the development of new MBs. Of the 56 new MBs, 29 (51.8%) appeared in the lobar location, 17 (30.4%) appeared in the deep location, and 10 (17.9%) appeared in the infratentorial location.
  
  
  CONCLUSIONS
  This study suggests that new microbleeds (MBs) can develop rapidly after acute ischemic stroke. Baseline MBs and severe small vessel disease are predictors for the development of new MBs. Further studies will be needed to investigate the clinical implications and mechanisms of these findings.
authors.affiliation: Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Songpa-gu, Seoul, Republic of Korea.
authors.forename: S-B
authors.initials: SB
authors.lastname: Jeon
authors.forename: S U
authors.initials: SU
authors.lastname: Kwon
authors.forename: A-H
authors.initials: AH
authors.lastname: Cho
authors.forename: S-C
authors.initials: SC
authors.lastname: Yun
authors.forename: J S
authors.initials: JS
authors.lastname: Kim
authors.forename: D-W
authors.initials: DW
authors.lastname: Kang
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply* / Q000473:pathology / Q000503:physiopathology*; D002545:Brain Ischemia / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology*; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors; D055815:Young Adult