title: Effect of Collaterals on Clinical Presentation, Baseline Imaging, Complications, and Outcome in Acute Stroke.
abstract: OBJECTIVE
  Good CTA collaterals independently predict good outcome in acute ischemic stroke. Our aim was to evaluate the role of collateral circulation and its added benefit over CTP-derived total ischemic volume as a predictor of baseline NIHSS score, total ischemic volume, hemorrhagic transformation, final infarct size, and a modified Rankin Scale score >2.
  
  
  METHODS
  This was a retrospective study of 395 patients with stroke dichotomized by recanalization (recanalization positive/recanalization negative) and collateral status. Clot burden score was quantified on baseline CTA. Total ischemic volumes were derived from thresholded CTP maps. Final infarct size was assessed on follow-up CT/MRI. We performed uni-/multivariate analyses for each outcome, adjusting for rtPA status, using general linear (continuous variables) and logistic (binary variables) regression. Model comparison with collateral score and total ischemic volume was performed using the F or likelihood ratio test.
  
  
  RESULTS
  Collateral presence independently and inversely predicted all outcomes except hemorrhagic transformation in patients who were recanalization negative and mRS >2 in patients who were recanalization positive. The greatest collateral benefit occurred in patients who were recanalization negative, contributing 16.5% and 19.2% of the variability for final infarct size and mRS >2. The collateral score model is superior to the total ischemic volume for mRS >2 prediction, but a combination of total ischemic volume and collateral score is superior for mRS >2 and final infarct prediction (24% and 28% variability, respectively). In patients who were recanalization positive, a model including collateral score and total ischemic volume was superior to that of total ischemic volume for hemorrhagic transformation and final infarct prediction but was muted compared with patients who were recanalization negative (11.3% and 16.9% variability).
  
  
  CONCLUSIONS
  Collateral circulation is an independent predictor of all outcomes, but the magnitude of significance varies, greater in patients who were recanalization negative versus recanalization positive. Total ischemic volume assessment is complementary to collateral score in many cases.
authors.affiliation: From the Division of Neuroradiology (E.M.F., J.K., R.I.A., S.-P.H., S.P.S., L.Z.), Department of Medical Imaging, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: E M
authors.initials: EM
authors.lastname: Fanou
authors.affiliation: From the Division of Neuroradiology (E.M.F., J.K., R.I.A., S.-P.H., S.P.S., L.Z.), Department of Medical Imaging, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: J
authors.identifier: http://orcid.org/0000-0002-0455-5455
authors.initials: J
authors.lastname: Knight
authors.affiliation: From the Division of Neuroradiology (E.M.F., J.K., R.I.A., S.-P.H., S.P.S., L.Z.), Department of Medical Imaging, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada richard.aviv@sunnybrook.ca.
authors.forename: R I
authors.initials: RI
authors.lastname: Aviv
authors.affiliation: From the Division of Neuroradiology (E.M.F., J.K., R.I.A., S.-P.H., S.P.S., L.Z.), Department of Medical Imaging, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: S-P
authors.initials: SP
authors.lastname: Hojjat
authors.affiliation: From the Division of Neuroradiology (E.M.F., J.K., R.I.A., S.-P.H., S.P.S., L.Z.), Department of Medical Imaging, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: S P
authors.initials: SP
authors.lastname: Symons
authors.affiliation: From the Division of Neuroradiology (E.M.F., J.K., R.I.A., S.-P.H., S.P.S., L.Z.), Department of Medical Imaging, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Division of Neuroradiology (M.W.), Department of Radiology, Stanford University, California.
authors.forename: M
authors.identifier: http://orcid.org/0000-0002-6726-3951
authors.initials: M
authors.lastname: Wintermark
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply*; D002533:Cerebral Angiography / Q000379:methods; D003097:Collateral Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012189:Retrospective Studies; D020521:Stroke / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome
chemical_list: D010959:Tissue Plasminogen Activator