title: Multiphase CT Angiography: A New Tool for the Imaging Triage of Patients with Acute Ischemic Stroke.
abstract: OBJECTIVE
  To describe the use of an imaging selection tool, multiphase computed tomographic (CT) angiography, in patients with acute ischemic stroke (AIS) and to demonstrate its interrater reliability and ability to help determine clinical outcome.
  
  
  METHODS
  The local ethics board approved this study. Data are from the pilot phase of PRoveIT, a prospective observational study analyzing utility of multimodal imaging in the triage of patients with AIS. Patients underwent baseline unenhanced CT, single-phase CT angiography of the head and neck, multiphase CT angiography, and perfusion CT. Multiphase CT angiography generates time-resolved images of pial arteries. Pial arterial filling was scored on a six-point ordinal scale, and interrater reliability was tested. Clinical outcomes included a 50% or greater decrease in National Institutes of Health Stroke Scale (NIHSS) over 24 hours and 90-day modified Rankin Scale (mRS) score of 0-2. The ability to predict clinical outcomes was compared between single-phase CT angiography, multiphase CT angiography, and perfusion CT by using receiver operating curve analysis, Akaike information criterion (AIC), and Bayesian information criterion (BIC).
  
  
  RESULTS
  A total of 147 patients were included. Interrater reliability for multiphase CT angiography is excellent (n = 30, κ = 0.81, P < .001). At receiver operating characteristic curve analysis, the ability to predict clinical outcome is modest (C statistic = 0.56, 95% confidence interval [CI]: 0.52, 0.63 for ≥50% decrease in NIHSS over 24 hours; C statistic = 0.6, 95% CI: 0.53, 0.68 for 90-day mRS score of 0-2) but better than that of models using single-phase CT angiography and perfusion CT (P < .05 overall). With AIC and BIC, models that use multiphase CT angiography are better than models that use single-phase CT angiography and perfusion CT for a decrease of 50% or more in NIHSS over 24 hours (AIC = 166, BIC = 171.7; values were lowest for multiphase CT angiography) and a 90-day mRS score of 0-2 (AIC = 132.1, BIC = 137.4; values were lowest for multiphase CT angiography).
  
  
  CONCLUSIONS
  Multiphase CT angiography is a reliable tool for imaging selection in patients with AIS.
authors: From the Calgary Stroke Program, Department of Clinical Neurosciences (B.K.M., C.D.d.E., E.M.Q., M.A., A.M.D., M.G.), Department of Radiology (B.K.M., C.D.d.E., M.A., L.H., A.M.D., M.G.), Department of Community Health Sciences (B.K.M.), Hotchkiss Brain Institute (B.K.M., A.M.D., M.G.); and Seaman Family MR Research Centre, Foothills Medical Centre (B.K.M., C.D.d.E., A.M.D., M.G.), University of Calgary, 1403-29th St NW, Calgary, AB, Canada T2N 2T9.
authors: Bijoy K
authors: BK
authors: Menon
authors: Christopher D
authors: CD
authors: d'Esterre
authors: Emmad M
authors: EM
authors: Qazi
authors: Mohammed
authors: M
authors: Almekhlafi
authors: Leszek
authors: L
authors: Hahn
authors: Andrew M
authors: AM
authors: Demchuk
authors: Mayank
authors: M
authors: Goyal
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000150:complications / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D020521:Stroke / Q000000981:diagnostic imaging* / Q000209:etiology; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000706:statistics & numerical data; D014218:Triage / Q000379:methods