title: Automated perfusion imaging for the evaluation of transient ischemic attack.
abstract: OBJECTIVE
  Diffusion-weighted imaging (DWI) is recommended for the evaluation of transient ischemic attack. Perfusion imaging can increase the yield of MRI in transient ischemic attack. We evaluated automated bolus perfusion (the time when the residue function reaches its maximum [TMax] and mean transit time [MTT]) and arterial spin labeling (ASL) sequences for the detection of ischemic lesions in patients with transient ischemic attack.
  
  
  METHODS
  We enrolled consecutive patients evaluated for suspicion of acute transient ischemic attack by multimodal MRI within 36 hours of symptom onset. Two independent raters assessed the presence and location of ischemic lesions blinded to the clinical presentation. The prevalence of ischemic lesions and the interrater agreement were 1,410 assessed.
  
  
  RESULTS
  From January 2010 to 2011, 93 patients were enrolled and 90 underwent perfusion imaging (69 bolus perfusion and 76 ASL). Overall, 25 of 93 patients (27%) were DWI-positive and 14 (15%) were perfusion-positive but DWI-negative (ASL n=9; TMax n=9; MTT n=2). MTT revealed an ischemic lesion in fewer patients than TMax (7 versus 20, P=0.004). Raters agreed on 89% of diffusion-weighted imaging cases, 89% of TMax, 87% o10f010 MTT, and 90% of ASL cases. The interrater agreement was good for DWI, TMax, and ASL (κ=0.73, 0.72, and 0.74, respectively) and fair for MTT (κ=0.43). Diffusion and/or perfusion were positive in 39 of 69 (57%) patients with a discharge diagnosis of possible ischemic event.
  
  
  CONCLUSIONS
  Our results suggest that in patients referred for suspicion of transient ischemic attack, automated TMax is more sensitive than MTT, and both ASL and TMax increase the yield of MRI for the detection of ischemic lesions.
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, 780 Welch Road, Suite 205, Palo Alto, CA 94304, USA.
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Kleinman
authors.forename: Greg
authors.initials: G
authors.lastname: Zaharchuk
authors.forename: Michael
authors.initials: M
authors.lastname: Mlynash
authors.forename: Alyshia A
authors.initials: AA
authors.lastname: Ogdie
authors.forename: Matus
authors.initials: M
authors.lastname: Straka
authors.forename: Maarten G
authors.initials: MG
authors.lastname: Lansberg
authors.forename: Neil E
authors.initials: NE
authors.lastname: Schwartz
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kemp
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Albers
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Olivot
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000175:diagnosis*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors