title: CT cerebral blood flow maps optimally correlate with admission diffusion-weighted imaging in acute stroke but thresholds vary by postprocessing platform.
abstract: OBJECTIVE
  Admission infarct core lesion size is an important determinant of management and outcome in acute (<9 hours) stroke. Our purposes were to: (1) determine the optimal CT perfusion parameter to define infarct core using various postprocessing platforms; and (2) establish the degree of variability in threshold values between these different platforms.
  
  
  METHODS
  We evaluated 48 consecutive cases with vessel occlusion and admission CT perfusion and diffusion-weighted imaging within 3 hours of each other. CT perfusion was acquired with a "second-generation" 66-second biphasic cine protocol and postprocessed using "standard" (from 2 vendors, "A-std" and "B-std") and "delay-corrected" (from 1 vendor, "A-dc") commercial software. Receiver operating characteristic curve analysis was performed comparing each CT perfusion parameter-both absolute and normalized to the contralateral uninvolved hemisphere-between infarcted and noninfarcted regions as defined by coregistered diffusion-weighted imaging.
  
  
  RESULTS
  Cerebral blood flow had the highest accuracy (receiver operating characteristic area under the curve) for all 3 platforms (P<0.01). The maximal areas under the curve for each parameter were: absolute cerebral blood flow 0.88, cerebral blood volume 0.81, and mean transit time 0.82 and relative Cerebral blood flow 0.88, cerebral blood volume 0.83, and mean transit time 0.82. Optimal receiver operating characteristic operating point thresholds varied significantly between different platforms (Friedman test, P<0.01).
  
  
  CONCLUSIONS
  Admission absolute and normalized "second-generation" cine acquired CT cerebral blood flow lesion volumes correlate more closely with diffusion-weighted imaging-defined infarct core than do those of CT cerebral blood volume or mean transit time. Although limited availability of diffusion-weighted imaging for some patients creates impetus to develop alternative methods of estimating core, the marked variability in quantification among different postprocessing software limits generalizability of parameter map thresholds between platforms.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Gray B285, 55 Fruit Street, Boston, MA 02114, USA.
authors.forename: Shahmir
authors.initials: S
authors.lastname: Kamalian
authors.forename: Shervin
authors.initials: S
authors.lastname: Kamalian
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Maas
authors.forename: Greg V
authors.initials: GV
authors.lastname: Goldmacher
authors.forename: Seyedmehdi
authors.initials: S
authors.lastname: Payabvash
authors.forename: Adnan
authors.initials: A
authors.lastname: Akbar
authors.forename: Pamela W
authors.initials: PW
authors.lastname: Schaefer
authors.forename: Karen L
authors.initials: KL
authors.lastname: Furie
authors.forename: R Gilberto
authors.initials: RG
authors.lastname: Gonzalez
authors.forename: Michael H
authors.initials: MH
authors.lastname: Lev
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002545:Brain Ischemia / Q000473:pathology; D002560:Cerebrovascular Circulation; D004058:Diffusion; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D012372:ROC Curve; D015203:Reproducibility of Results; D020521:Stroke / Q000473:pathology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*