title: Yield of CT perfusion for the evaluation of transient ischaemic attack.
abstract: BACKGROUND
  Magnetic resonance diffusion-weighted imaging and perfusion-weighted imaging are able to identify ischaemic 'footprints' in transient ischaemic attack. Computed tomography perfusion (CTP) may be useful for patient triage and subsequent management. To date, less than 100 cases have been reported, and none have compared computed tomography perfusion to perfusion-weighted imaging (PWI). We sought to define the yield of computed tomography perfusion for the evaluation of transient ischaemic attack.
  
  
  METHODS
  Consecutive patients with a discharge diagnosis of possible or definite transient ischaemic event who underwent computed tomography perfusion were included in this study. The presence of an ischaemic lesion was assessed on noncontrast computed tomography, automatically deconvolved CTPTMax (Time till the residue function reaches its maximum), and when available on diffusion-weighted imaging and PWITMax maps.
  
  
  RESULTS
  Thirty-four patients were included and 17 underwent magnetic resonance imaging. Median delay between onset and computed tomography perfusion was 4·4 h (Interquartile range [IQR]: 1·9-9·6), and between computed tomography perfusion and magnetic resonance imaging was 11 h (Interquartile range: 3·8-22). Noncontrast computed tomography was negative in all cases, while CTPTMax identified an ischaemic lesion in 12/34 patients (35%). In the subgroup of patients with multimodal magnetic resonance imaging, an ischaemic lesion was found in six (35%) patients using CTPTMax versus nine (53%) on magnetic resonance imaging (five diffusion-weighted imaging, nine perfusion-weighted imaging). The additional yield of CTPTMax over computed tomography angiography was significant in the evaluation of transient ischaemic attack (12 vs. 3, McNemar, P = 0·004).
  
  
  CONCLUSIONS
  CTPTMax found an ischaemic lesion in one-third of acute transient ischaemic attack patients. Computed tomography perfusion may be an acceptable substitute when magnetic resonance imaging is unavailable or contraindicated, and has additional yield over computed tomography angiography. Further studies evaluating the outcome of patients with computed tomography perfusion lesions in transient ischaemic attack are justified at this time.
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Kleinman
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Mlynash
authors.affiliation: Department of Radiology, Lucas Magnetic Resonance Spectroscopy and Imaging Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Zaharchuk
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Alyshia A
authors.initials: AA
authors.lastname: Ogdie
authors.affiliation: Department of Radiology, Lucas Magnetic Resonance Spectroscopy and Imaging Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Matus
authors.initials: M
authors.lastname: Straka
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Maarten G
authors.initials: MG
authors.lastname: Lansberg
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Schwartz
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Singh
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kemp
authors.affiliation: Department of Radiology, Lucas Magnetic Resonance Spectroscopy and Imaging Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Bammer
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Albers
authors.affiliation: Department of Neurology and Neurological Sciences, Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA, USA.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Olivot
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002546:Ischemic Attack, Transient / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed