title: Quantitative cerebral MR perfusion imaging: preliminary results in stroke.
abstract: OBJECTIVE
  To evaluate quantitative cerebral blood flow (qCBF) with traditional time-based measurements or metrics of cerebral perfusion: time to peak (Tmax) and mean transit time (MTT) in stroke patients.
  
  
  METHODS
  Nine ischemic stroke patients (four male, five female, 63 ± 16 years old) were included in the study which was Health Insurance Portability and Accountability Act compliant and institutional review board approved. Cerebral perfusion was quantified using the Bookend method. Mean values of qCBF, Tmax, and MTT were determined in regions of interest (ROIs). ROIs were drawn on diffusion weighted images in diffusion positive, critically ischemic (CI), in ipsilateral normal region immediately surrounding the critically ischemic region, the presumed penumbra (PP), and in contralateral diffusion negative control, presumed normal region (PN) of gray and white matter separately (GM and WM).
  
  
  RESULTS
  In both GM and WM, qCBF measures distinguished the studied brain regions with the most markedly reduced values in regions corresponding to extent of likely ischemic injury. In planned comparisons, only qCBF measurements differed significantly between CI and PP tissues. ROC analysis supported the utility of qCBF for discriminating brain regions differing in the likely extent of ischemic injury (CI and PN regions - qCBF: area under the curve [AUC] = 0.96, Tmax: AUC = 0.96, MTT: AUC = 0.72). Importantly, qCBF afforded the best discrimination of CI and PP regions (qCBF: AUC = 0.82, Tmax: AUC = 0.65, MTT: AUC = 0.52).
  
  
  CONCLUSIONS
  This initial evaluation indicates that quantitative MRI perfusion is feasible in ischemic stroke patients. qCBF derived with this strategy provide enhanced discrimination of CI and PP compared to time-based imaging metrics. This approach merits investigation in larger clinical studies.
authors.affiliation: Department of Biomedical Engineering, Northwestern University, Evanston, Illinois 60611, USA.
authors.forename: Maulin K
authors.initials: MK
authors.lastname: Shah
authors.forename: Wanyong
authors.initials: W
authors.lastname: Shin
authors.forename: Vishal S
authors.initials: VS
authors.lastname: Parikh
authors.forename: Ann
authors.initials: A
authors.lastname: Ragin
authors.forename: Jessy
authors.initials: J
authors.lastname: Mouannes
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bernstein
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Walker
authors.forename: Hem
authors.initials: H
authors.lastname: Bhatt
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Carroll
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D020521:Stroke / Q000175:diagnosis / Q000503:physiopathology*; D016896:Treatment Outcome