title: Six-minute magnetic resonance imaging protocol for evaluation of acute ischemic stroke: pushing the boundaries.
abstract: OBJECTIVE
  If magnetic resonance imaging (MRI) is to compete with computed tomography for evaluation of patients with acute ischemic stroke, there is a need for further improvements in acquisition speed.
  
  
  METHODS
  Inclusion criteria for this prospective, single institutional study were symptoms of acute ischemic stroke within 24 hours onset, National Institutes of Health Stroke Scale ≥3, and absence of MRI contraindications. A combination of echo-planar imaging (EPI) and a parallel acquisition technique were used on a 3T magnetic resonance (MR) scanner to accelerate the acquisition time. Image analysis was performed independently by 2 neuroradiologists.
  
  
  RESULTS
  A total of 62 patients met inclusion criteria. A repeat MRI scan was performed in 22 patients resulting in a total of 84 MRIs available for analysis. Diagnostic image quality was achieved in 100% of diffusion-weighted imaging, 100% EPI-fluid attenuation inversion recovery imaging, 98% EPI-gradient recalled echo, 90% neck MR angiography and 96% of brain MR angiography, and 94% of dynamic susceptibility contrast perfusion scans with interobserver agreements (k) ranging from 0.64 to 0.84. Fifty-nine patients (95%) had acute infarction. There was good interobserver agreement for EPI-fluid attenuation inversion recovery imaging findings (k=0.78; 95% confidence interval, 0.66-0.87) and for detection of mismatch classification using dynamic susceptibility contrast-Tmax (k=0.92; 95% confidence interval, 0.87-0.94). Thirteen acute intracranial hemorrhages were detected on EPI-gradient recalled echo by both observers. A total of 68 and 72 segmental arterial stenoses were detected on contrast-enhanced MR angiography of the neck and brain with k=0.93, 95% confidence interval, 0.84 to 0.96 and 0.87, 95% confidence interval, 0.80 to 0.90, respectively.
  
  
  CONCLUSIONS
  A 6-minute multimodal MR protocol with good diagnostic quality is feasible for the evaluation of patients with acute ischemic stroke and can result in significant reduction in scan time rivaling that of the multimodal computed tomographic protocol.
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.). kambiznael@gmail.com.
authors.forename: Kambiz
authors.initials: K
authors.lastname: Nael
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Rihan
authors.initials: R
authors.lastname: Khan
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Gagandeep
authors.initials: G
authors.lastname: Choudhary
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Arash
authors.initials: A
authors.lastname: Meshksar
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Pablo
authors.initials: P
authors.lastname: Villablanca
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Jennifer
authors.initials: J
authors.lastname: Tay
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Kendra
authors.initials: K
authors.lastname: Drake
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Coull
authors.affiliation: From the Departments of Medical Imaging (K.N., R.K., G.C., A.M., C.S.K.) and Neurology (J.T., K.D., B.M.C., C.S.K.), University of Arizona, Tucson; and Department of Radiological Sciences, University of California, Los Angeles (P.V.).
authors.forename: Chelsea S
authors.initials: CS
authors.lastname: Kidwell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000175:diagnosis*; D002544:Cerebral Infarction / Q000175:diagnosis*; D002985:Clinical Protocols / Q000592:standards*; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods / Q000592:standards; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods / Q000592:standards; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods / Q000592:standards; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020521:Stroke / Q000175:diagnosis*
keywords: magnetic resonance angiography; magnetic resonance imaging; perfusion imaging; stroke