title: Extensive blooming artifact predicts no recanalization after intravenous thrombolysis.
abstract: OBJECTIVE
  Hemosiderin exhibits a stronger T2 shortening effect than deoxyhemoglobin. The extent of the 'blooming artifact' may therefore reflect a composition of different iron forms. Our aim was to investigate the relationship between extent of susceptibility vessel sign (SVS) width beyond the lumen and middle cerebral artery (MCA) recanalization.
  
  
  METHODS
  Clinical and imaging data from consecutive acute ischaemic stroke patients with MCA occlusion who underwent susceptibility-weighted imaging (SWI) before intravenous thrombolysis were examined. The source images of magnitude and angiography were used to obtain the width of SVS and MCA at the interface, respectively.
  
  
  RESULTS
  The presence of MCA SVS was observed in 64 patients on initial SWI scans and recanalization was observed in 30 (46.9%) patients. The overestimation ratio of thrombus width on SWI was an acceptable predictor for no recanalization [odds ratio 1.360 per 0.1; 95% confidence interval (CI) 1.093-1.691; P = 0.006]. The optimal cut-off point was identified at 1.943, and this yielded a sensitivity of 67.6% and a specificity of 86.7%. Extensive blooming artifact, defined as overestimation ratio ≥2, independently predicted no recanalization (odds ratio 9.687, 95% CI 1.974-47.545; P = 0.005) and unfavorable outcome (odds ratio 4.916, 95% CI 1.049-23.051; P = 0.043).
  
  
  CONCLUSIONS
  The extent of SVS width beyond the lumen might reflect the content of hemosiderin. An extreme overestimation ratio might indicate aged thrombus, which may be resistant to thrombolysis.
authors.affiliation: Department of Neurology, School of Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou, China.
authors.forename: S
authors.identifier: http://orcid.org/0000-0001-6425-0672
authors.initials: S
authors.lastname: Yan
authors.affiliation: Department of Neurology, School of Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Neurology, School of Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Neurology, School of Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou, China.
authors.forename: M
authors.initials: M
authors.lastname: Xu
authors.affiliation: Department of Neurology, School of Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Han
authors.affiliation: Department of Neurosurgery, School of Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou, China.
authors.forename: A
authors.initials: A
authors.lastname: Shao
authors.affiliation: University of California - Los Angeles Stroke Center, Los Angeles, CA, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Liebeskind
authors.affiliation: Department of Neurology, School of Medicine, Second Affiliated Hospital of Zhejiang University, Hangzhou, China.
authors.forename: M
authors.initials: M
authors.lastname: Lou
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000188:drug therapy; D020767:Intracranial Thrombosis / Q000000981:diagnostic imaging* / Q000188:drug therapy; D018810:Magnetic Resonance Angiography / Q000592:standards*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D012680:Sensitivity and Specificity; D015912:Thrombolytic Therapy / Q000379:methods*
keywords: magnetic resonance imaging; recanalization; stroke; thrombolytic therapy