title: Changes in Cerebral Perfusion with Induced Hypertension in Aneurysmal Subarachnoid Hemorrhage: A Pilot and Feasibility Study.
abstract: BACKGROUND
  The effects of induced hypertension (IH) on cerebral perfusion after subarachnoid hemorrhage (SAH) are unclear. The objectives of this investigation are to: (1) determine whether there are differences in cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) measured with computed tomography perfusion (CTP) before and after IH; (2) evaluate differences in the presence of infarction and clinical outcome between patients with and without IH.
  
  
  METHODS
  We performed a retrospective cohort analysis of 25 aneurysmal SAH patients. IH was initiated as per the standard institutional protocol when patients showed clinical symptoms of delayed cerebral ischemia (DCI). Differences in CBF, CBV, and MTT between early (<72 h after aneurysm rupture) and late (7-10 days after aneurysm rupture) CTP were quantified in patients with (n = 13) and without IH (n = 12). Outcome measures included cerebral infarction and clinical outcome at 3 months.
  
  
  RESULTS
  Early MTT was significantly greater in the IH group compared to the no-IH group. There was no difference in early or late CBV or CBF between the two groups. In patients that received IH, there was a significant decrease in MTT between the early (7.0 ± 1.2 s) and late scans (5.8 ± 1.6 s; p = 0.005). There was no difference in the incidence of infarction (5/13 vs. 2/11) or poor outcome (3/11 vs. 6/13) between the IH and no-IH groups, respectively (p > 0.05).
  
  
  CONCLUSIONS
  Elevated MTT is a significant factor for the development of DCI in patients eventually requiring IH therapy and is improved by IH treatment. Therapies to prevent DCI and improve clinical outcome may need to be initiated earlier, when cerebral perfusion abnormalities are first identified.
authors.affiliation: Department of Medical Imaging, University of Toronto, 30 Bond Street, Room 3-077CC, Toronto, ON, M5B 1W8, Canada. amanda.murphy@mail.utoronto.ca.
authors.forename: Amanda
authors.identifier: http://orcid.org/0000-0002-1792-8847
authors.initials: A
authors.lastname: Murphy
authors.affiliation: St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Airton Leonardo
authors.initials: AL
authors.lastname: de Oliveira Manoel
authors.affiliation: Department of Neurosurgery, St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: R Loch
authors.initials: RL
authors.lastname: Macdonald
authors.affiliation: Department of Critical Care, St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Baker
authors.affiliation: Robarts Research Institute, London, ON, Canada.
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
authors.affiliation: Department of Medical Imaging, St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Marotta
authors.affiliation: Department of Medical Imaging, St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Walter
authors.initials: W
authors.lastname: Montanera
authors.affiliation: Department of Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Aviv
authors.affiliation: Department of Medical Imaging, St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Aditya
authors.initials: A
authors.lastname: Bharatha
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000517:prevention & control*; D002533:Cerebral Angiography; D000071937:Cerebral Blood Volume / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D000072226:Computed Tomography Angiography; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000139:chemically induced*; D002532:Intracranial Aneurysm / Q000150:complications; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012189:Retrospective Studies; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome
keywords: CT perfusion; Induced hypertension; Subarachnoid hemorrhage