title: Cerebral perfusion and cerebrovascular reactivity are reduced in white matter hyperintensities.
abstract: OBJECTIVE
  There is growing evidence that white matter hyperintensities (WMH) should not be considered as benign age-dependent changes on MR images but indicate pathological changes with clinical consequences. Previous studies comparing subjects with WMH to normal controls have reported global reductions in cerebral blood flow (CBF) and cerebral vascular reactivity. In this study, we examined localized hemodynamic status to compare WMH to normal appearing white matter (NAWM).
  
  
  METHODS
  A group of 21 normal 85-year-old subjects were studied using dynamic contrast-enhanced MRI together with administration of acetazolamide. From a combination of anatomic images with different signal weighting, regions of interest were generated corresponding to gray and white matter and WMH. Localized measurements of CBF and cerebral blood volume (CBV) and mean transit time were obtained directly within WMH and NAWM.
  
  
  RESULTS
  When comparing WMH to NAWM, measurements showed significantly lower CBF (P=0.004) and longer mean transit time (P< 0.001) in WMH but no significant difference in CBV (P=0.846). The increases in CBF and CBV induced by acetazolamide were significantly smaller in WMH than in NAWM (P=0.026, P<0.001).
  
  
  CONCLUSIONS
  These results show that a change in the hemodynamic status is present within the WMH, making these areas more likely to be exposed to transient ischemia inducing myelin rarefaction. In the future, MRI may be used to examine the effect of therapeutic strategies designed to prevent or normalize vascular changes.
authors.affiliation: Danish Research Centre for Magnetic Resonance, Hvidovre Hospital, Hvidovre, Denmark. marstrand@dadlnet.dk
authors.forename: J R
authors.initials: JR
authors.lastname: Marstrand
authors.forename: E
authors.initials: E
authors.lastname: Garde
authors.forename: E
authors.initials: E
authors.lastname: Rostrup
authors.forename: P
authors.initials: P
authors.lastname: Ring
authors.forename: S
authors.initials: S
authors.lastname: Rosenbaum
authors.forename: E L
authors.initials: EL
authors.lastname: Mortensen
authors.forename: H B W
authors.initials: HB
authors.lastname: Larsson
mesh_terms: D000086:Acetazolamide / Q000008:administration & dosage; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008955:Models, Cardiovascular; D011237:Predictive Value of Tests; D012016:Reference Values
chemical_list: D000086:Acetazolamide