title: Optimal MRI sequence for identifying occlusion location in acute stroke: which value of time-resolved contrast-enhanced MRA?
abstract: OBJECTIVE
  Identifying occlusion location is crucial for determining the optimal therapeutic strategy during the acute phase of ischemic stroke. The purpose of this study was to assess the diagnostic efficacy of MR imaging, including conventional sequences plus time-resolved contrast-enhanced MRA in comparison with DSA for identifying arterial occlusion location.
  
  
  METHODS
  Thirty-two patients with 34 occlusion levels referred for thrombectomy during acute cerebral stroke events were consecutively included from August 2010 to December 2012. Before thrombectomy, we performed 3T MR imaging, including conventional 3D-TOF and gradient-echo T2 sequences, along with time-resolved contrast-enhanced MRA of the extra- and intracranial arteries. The 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA results were consensually assessed by 2 neuroradiologists and compared with prethrombectomy DSA results in terms of occlusion location. The Wilcoxon test was used for statistical analysis to compare MR imaging sequences with DSA, and the κ coefficient was used to determine intermodality agreement.
  
  
  RESULTS
  The occlusion level on the 3D-TOF and gradient-echo T2 images differed significantly from that of DSA (P < .001 and P = .002, respectively), while no significant difference was observed between DSA and time-resolved contrast-enhanced MRA (P = .125). κ coefficients for intermodality agreement with DSA (95% CI, percentage agreement) were 0.43 (0.3%-0.6; 62%), 0.32 (0.2%-0.5; 56%), and 0.81 (0.6%-1.0; 88%) for 3D-TOF, gradient-echo T2, and time-resolved contrast-enhanced MRA, respectively.
  
  
  CONCLUSIONS
  The time-resolved contrast-enhanced MRA sequence proved reliable for identifying occlusion location in acute stroke with performance superior to that of 3D-TOF and gradient-echo T2 sequences.
authors.affiliation: From the Departments of Neuroradiology (A.L.B., H.R., J.-C.F., J.-Y.G.) anthony.le.bras@chu-rennes.fr.
authors.forename: A
authors.initials: A
authors.lastname: Le Bras
authors.affiliation: From the Departments of Neuroradiology (A.L.B., H.R., J.-C.F., J.-Y.G.) Unité VISAGE U746 INSERM-INRIA, IRISA UMR CNRS 6074 (H.R., J.-C.F., J.-Y.G.), University of Rennes, Rennes, France.
authors.forename: H
authors.initials: H
authors.lastname: Raoult
authors.affiliation: From the Departments of Neuroradiology (A.L.B., H.R., J.-C.F., J.-Y.G.) Unité VISAGE U746 INSERM-INRIA, IRISA UMR CNRS 6074 (H.R., J.-C.F., J.-Y.G.), University of Rennes, Rennes, France.
authors.forename: J-C
authors.initials: JC
authors.lastname: Ferré
authors.affiliation: Neurology (T.R.), Centre Hospitalier Universitaire Rennes, Rennes, France.
authors.forename: T
authors.initials: T
authors.lastname: Ronzière
authors.affiliation: From the Departments of Neuroradiology (A.L.B., H.R., J.-C.F., J.-Y.G.) Unité VISAGE U746 INSERM-INRIA, IRISA UMR CNRS 6074 (H.R., J.-C.F., J.-Y.G.), University of Rennes, Rennes, France.
authors.forename: J-Y
authors.initials: JY
authors.lastname: Gauvrit
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography / Q000379:methods*; D002544:Cerebral Infarction / Q000175:diagnosis* / Q000601:surgery; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008536:Meglumine; D008875:Middle Aged; D009942:Organometallic Compounds; D012680:Sensitivity and Specificity; D017131:Thrombectomy
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D008536:Meglumine; C072417:gadoterate meglumine