title: Validity and reliability of a quantitative computed tomography score in predicting outcome of hyperacute stroke before thrombolytic therapy. ASPECTS Study Group. Alberta Stroke Programme Early CT Score.
abstract: BACKGROUND
  Computed tomography (CT) must be done before thrombolytic treatment of hyperacute ischaemic stroke, but the significance of early ischaemic change on CT is unclear. We tested a quantitative CT score, the Alberta Stroke Programme Early CT Score (ASPECTS).
  
  
  METHODS
  203 consecutive patients with ischaemic stroke were treated with intravenous alteplase within 3 h of symptom onset in two North American teaching hospitals. All pretreatment CT scans were prospectively scored. The score divides the middle-cerebral-artery territory into ten regions of interest. Primary outcomes were symptomatic intracerebral haemorrhage and 3-month functional outcome. The sensitivity and specificity of ASPECTS for the primary outcomes were calculated. Logistic regression was used to test the association between the score on ASPECTS and the primary outcomes.
  
  
  RESULTS
  Ischaemic changes on the baseline CT were seen in 117 (75%) of 156 treated patients with anterior-circulation ischaemia included in the analysis (23 had ischaemia in the posterior circulation and 24 were treated outside the protocol). Baseline ASPECTS value correlated inversely with the severity of stroke on the National Institutes of Health Stroke Scale (r=-0.56, p<0.001). Baseline ASPECTS value predicted functional outcome and symptomatic intracerebral haemorrhage (p<0.001, p=0.012, respectively). The sensitivity of ASPECTS for functional outcome was 0.78 and specificity 0.96; the values for symptomatic intracerebral haemorrhage were 0.90 and 0.62. Agreement between observers for ASPECTS, with knowledge of the affected hemisphere, was good (kappa statistic 0.71-0.89).
  
  
  CONCLUSIONS
  This CT score is simple and reliable and identifies stroke patients unlikely to make an independent recovery despite thrombolytic treatment.
authors.affiliation: Department of Clinical Neurosciences, University of Calgary, Canada.
authors.forename: P A
authors.initials: PA
authors.lastname: Barber
authors.forename: A M
authors.initials: AM
authors.lastname: Demchuk
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: A M
authors.initials: AM
authors.lastname: Buchan
mesh_terms: D000208:Acute Disease; D000368:Aged; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000188:drug therapy; D002543:Cerebral Hemorrhage / Q000000981:diagnostic imaging; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D011446:Prospective Studies; D015203:Reproducibility of Results; D015912:Thrombolytic Therapy; D010959:Tissue Plasminogen Activator / Q000009:adverse effects / Q000627:therapeutic use*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D016896:Treatment Outcome
chemical_list: D010959:Tissue Plasminogen Activator