title: Vasoreactivity and peri-infarct hyperintensities in stroke.
abstract: OBJECTIVE
  It is unknown if impaired cerebral vasoreactivity recovers after ischemic stroke, and whether it compromises perfusion in regions surrounding infarct and other vascular territories. We investigated the regional differences in CO2 vasoreactivity (CO2 VR) and their relationships to peri-infarct T2 hyperintensities (PIHs), chronic infarct volumes, and clinical outcomes.
  
  
  METHODS
  We studied 39 subjects with chronic large middle cerebral artery territory infarcts and 48 matched controls. Anatomic and three-dimensional continuous arterial spin labeling imaging at 3-Tesla MRI were used to measure regional cerebral blood flow (CBF) and CO2 VR during normocapnia, hypercapnia, and hypocapnia in main arteries distributions.
  
  
  RESULTS
  Stroke patients showed a significantly lower augmentation of blood flow at increased CO2 but greater reduction of blood flow with decreased CO2 than the control group. This altered vasoregulatory response was observed both ipsilateral and contralateral to the stroke. Lower CO2 VR on the stroke side was associated with PIHs, greater infarct volume, and worse outcomes. The cases with PIHs (n = 27) had lower CBF during all conditions bilaterally (p < 0.0001) compared to cases with infarct only.
  
  
  CONCLUSIONS
  Perfusion augmentation is inadequate in multiple vascular territories in patients with large artery ischemic infarcts, but vasoconstriction is preserved. Peri-infarct T2 hyperintensities are associated with lower blood flow. Strategies aimed to preserve vasoreactivity after an ischemic stroke should be tested for their effect on long-term outcomes.
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
authors.forename: P
authors.initials: P
authors.lastname: Zhao
authors.forename: D C
authors.initials: DC
authors.lastname: Alsop
authors.forename: A
authors.initials: A
authors.lastname: Abduljalil
authors.forename: M
authors.initials: M
authors.lastname: Selim
authors.forename: L
authors.initials: L
authors.lastname: Lipsitz
authors.forename: P
authors.initials: P
authors.lastname: Novak
authors.forename: L
authors.initials: L
authors.lastname: Caplan
authors.forename: K
authors.initials: K
authors.lastname: Hu
authors.forename: V
authors.initials: V
authors.lastname: Novak
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000473:pathology / Q000503:physiopathology*; D014661:Vasoconstriction / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*