title: Positron emission tomograghy with [¹³N]ammonia evidences long-term cerebral hyperperfusion after 2h-transient focal ischemia.
abstract: OBJECTIVE
  It is well known that after cerebral ischemia, brain suffers blood flow changes over time that have been correlated with inflammation, angiogenesis and functional recovery processes. Nevertheless, post-ischemic spatiotemporal changes of brain perfusion have not been fully investigated to date. Here we tested whether PET with [¹³N]ammonia would evidence the perfusion changes presented by different brain regions in an experimental model of brain ischemia.
  
  
  METHODS
  Seven rats were subjected to a 2-h transient middle cerebral artery occlusion with reperfusion. PET studies were performed longitudinally using [¹³N]ammonia at 1, 3, 7, 14, 21 and 28 days after cerebral ischemia.
  
  
  RESULTS
  In vivo PET imaging showed a significant increase in [¹³N]ammonia uptake at 7 days after cerebral ischemia with respect to one day after the occlusion in the cerebral territory irrigated by the MCA in both the ischemic and contralateral hemispheres. This increase was followed by a return to control values at day 28 after ischemia onset. Brain regions located both inside and outside the primary infarct areas showed similar perfusion changes after cerebral ischemia.
  
  
  CONCLUSIONS
  [¹³N]ammonia shows hemodynamic changes after stroke involving hyperperfusion that might be related to angiogenesis and functional recovery. Long-term blood hyperperfusion is found both in ischemic and remote areas to infarction. These results may contribute to a better understanding of the evolution of cerebral ischemic lesion in animal models.
authors.affiliation: Molecular Imaging Unit, CIC biomaGUNE, Spain. amartin@cicbiomagune.es
authors.forename: A
authors.initials: A
authors.lastname: Martín
authors.forename: E
authors.initials: E
authors.lastname: San Sebastián
authors.forename: V
authors.initials: V
authors.lastname: Gómez-Vallejo
authors.forename: J
authors.initials: J
authors.lastname: Llop
mesh_terms: D000641:Ammonia; D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000503:physiopathology; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019275:Radiopharmaceuticals; D000641:Ammonia