title: Measurement of cerebrovascular changes in cats after transient ischemia using dynamic magnetic resonance imaging.
abstract: OBJECTIVE
  Hemodynamic changes associated with acute ischemia cannot be measured with conventional nuclear magnetic resonance imaging. In this study, we used dynamic susceptibility-contrast magnetic resonance imaging to measure the changes in vascular transit time and relative cerebral blood volume in a feline occlusion-reperfusion model.
  
  
  METHODS
  Dynamic susceptibility-contrast measurements were obtained before and during 10 minutes of global cerebral ischemia and for up to 3 hours after the onset of reperfusion. A cerebral blood flow index was calculated from the vascular transit time and relative cerebral blood volume measurements. Functional maps were constructed to demonstrate the regional hemodynamic differences resulting from the induced ischemia.
  
  
  RESULTS
  During the early phase after reperfusion, both the relative cerebral blood volume and blood flow index rose sharply, followed by a fall to near-basal levels at 45 minutes (1 x control and 1.3 x control, respectively). Thereafter, the volume rose slowly, whereas the flow index continued to drop. At 3 hours, cerebral blood volume had reached 1.6 times its control value, whereas the flow index had returned to its base value.
  
  
  CONCLUSIONS
  The hemodynamic behavior we observed in our model reflects the independent responses of the cerebral blood volume and flow index to ischemic insult. Measurements acquired by our method were consistent with the temporal behavior reported in previous radionuclide studies. Susceptibility-contrast nuclear magnetic resonance tomographic imaging proved to be valuable in detecting and quantifying both immediate and subsequent changes in the hemodynamic state of the ischemic and hyperemic feline brain.
authors.affiliation: Massachusetts General Hospital NMR Center, Department of Radiology, Charlestown 02129.
authors.forename: L M
authors.initials: LM
authors.lastname: Hamberg
authors.forename: R
authors.initials: R
authors.lastname: Macfarlane
authors.forename: E
authors.initials: E
authors.lastname: Tasdemiroglu
authors.forename: P
authors.initials: P
authors.lastname: Boccalini
authors.forename: G J
authors.initials: GJ
authors.lastname: Hunter
authors.forename: J W
authors.initials: JW
authors.lastname: Belliveau
authors.forename: M A
authors.initials: MA
authors.lastname: Moskowitz
authors.forename: B R
authors.initials: BR
authors.lastname: Rosen
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000503:physiopathology*; D002415:Cats; D002533:Cerebral Angiography; D002536:Cerebral Arteries / Q000503:physiopathology*; D003287:Contrast Media / Q000008:administration & dosage; D004195:Disease Models, Animal; D006439:Hemodynamics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012039:Regional Blood Flow
chemical_list: D003287:Contrast Media