title: CT perfusion quantification of small-vessel ischemic severity.
abstract: OBJECTIVE
  Cerebral blood flow (CBF) abnormalities are previously demonstrated in white matter disease. A gradation of change may exist between patients with mild and more severe white matter disease. An association between blood brain barrier dysfunction, increasing age and white matter disease is also suggested. The purpose of this study was to quantify and correlate white matter disease severity and CT perfusion (CTP)-derived CBF and to determine whether permeability surface abnormality increases with white matter disease severity.
  
  
  METHODS
  One hundred twenty patients with strokelike symptoms underwent CTP and MR imaging. Of these, 35 patients (15 women, 20 men; age, 66 +/- 15.7 years) with rapidly resolving symptoms and normal imaging characteristics consistent with transient ischemic attack were retrospectively reviewed and constituted the study cohort. Two blinded neurologists rated white matter severity, assigning age-related white matter change (ARWMC) scores. Patients were dichotomized a priori into mild and moderate-to-severe. CBF, cerebral blood volume (CBV), mean transit time (MTT), and permeability surface product maps were calculated for periventricular and subcortical white matter regions and average white and gray matter. Associations with white matter severity were tested by uni- and multivariate logistic regression analyses. Receiver operating characteristic analysis was performed.
  
  
  RESULTS
  White matter disease was mild in 26 patients and moderate-to-severe in 9. Age was associated with increased likelihood of having moderate-to-severe white matter disease (P = .02). ARWMC correlated with subcortical (r = -0.50, P < .001) and average CBF (r = -0.55, P < .001). White matter severity was associated with subcortical (P = .03) and average (P = .03) white matter CBF, with a trend toward periventricular white matter CBF (P = .05). Uni- and multivariate analysis controlling for the confounding effect of age demonstrated significant association between white matter severity and subcortical (P = .032) white matter CBF. Area under the curve was 0.82. No permeability surface abnormality was found.
  
  
  CONCLUSIONS
  CTP-derived subcortical white matter CBF is independently associated with white matter disease severity.
authors.affiliation: Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: T J
authors.initials: TJ
authors.lastname: Huynh
authors.forename: B
authors.initials: B
authors.lastname: Murphy
authors.forename: J A
authors.initials: JA
authors.lastname: Pettersen
authors.forename: H
authors.initials: H
authors.lastname: Tu
authors.forename: D J
authors.initials: DJ
authors.lastname: Sahlas
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: S P
authors.initials: SP
authors.lastname: Symons
authors.forename: S
authors.initials: S
authors.lastname: Black
authors.forename: T-Y
authors.initials: TY
authors.lastname: Lee
authors.forename: R I
authors.initials: RI
authors.lastname: Aviv