title: Attributing hypodensities on CT to angiographic vasospasm is not sensitive and unreliable.
abstract: OBJECTIVE
  The presence of low-density areas on CT is used in clinical decision-making regarding treatment of angiographic vasospasm as well as in research as a surrogate marker for severity of angiographic vasospasm. We assess the interobserver variability in attributing hypodensities on CT to angiographic vasospasm-related delayed ischemic neurological deficit.
  
  
  METHODS
  Three experienced reviewers, 2 neurosurgeons, and a neuroradiologist independently reviewed CT scans of 413 patients enrolled in the Clazosentan to Overcome Neurological iSChemia and Infarction OccUrring after Subarachnoid hemorrhage (CONSCIOUS-1) trial, who universally underwent catheter angiography to determine severity of angiographic vasospasm. Interobserver variability was calculated using the κ statistic and the χ(2) test was used to determine associations between dichotomized outcomes.
  
  
  RESULTS
  There was considerable interobserver variability in attributing CT hypodensities to vasospasm-related delayed ischemic neurological deficit (κ=0.51-0.78; 95% CI, 0.35-0.90). Patients with hypodensities attributed to delayed ischemic neurological deficit were significantly more likely to have severe angiographic vasospasm (P=0.001), but a substantial proportion of these patients (19%) also had mild or no spasm. CT hypodensities had a sensitivity and specificity of 41% and 93%, respectively, in identifying patients with severe angiographic vasospasm, even with expert consensus that these represent angiographic vasospasm-related delayed ischemic neurological deficit.
  
  
  CONCLUSIONS
  We find considerable interobserver variability in attributing CT hypodensities to angiographic vasospasm and propose that they may not be a robust marker of severity of angiographic vasospasm, even with unanimous expert agreement that they are a result of vasospasm-related delayed ischemic neurological deficit.
  
  
  BACKGROUND
  URL: www.clinicaltrials.gov. Unique identifier: NCT00111085.
authors: Division of Neurosurgery, St Michael's Hospital, Toronto, ON M5B 1W8, Canada.
authors: George M
authors: GM
authors: Ibrahim
authors: Stephan
authors: S
authors: Weidauer
authors: Hartmut
authors: H
authors: Vatter
authors: Andreas
authors: A
authors: Raabe
authors: R Loch
authors: RL
authors: Macdonald
mesh_terms: D000328:Adult; D003657:Decision Making; D004146:Dioxanes / Q000627:therapeutic use; D006801:Humans; D011725:Pyridines / Q000627:therapeutic use; D011743:Pyrimidines / Q000627:therapeutic use; D011859:Radiography; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging* / Q000188:drug therapy; D013449:Sulfonamides / Q000627:therapeutic use; D013777:Tetrazoles / Q000627:therapeutic use; D020301:Vasospasm, Intracranial / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000517:prevention & control
chemical_list: D004146:Dioxanes; D011725:Pyridines; D011743:Pyrimidines; D013449:Sulfonamides; D013777:Tetrazoles; C109641:clazosentan