title: Serial Quantitative Computed Tomography Perfusion in Aneurysmal Subarachnoid Hemorrhage.
abstract: OBJECTIVE
  Computed tomography perfusion (CTP) has been performed to predict which patients with aneurysmal subarachnoid hemorrhage are at risk of developing delayed cerebral ischemia (DCI). Patients with severe arterial narrowing may have significant reduction in perfusion. However, many patients have less severe arterial narrowing. There is a paucity of literature evaluating perfusion changes which occur with mild to moderate narrowing. The purpose of our study was to investigate serial whole-brain CTP/computed tomography angiography in aneurysm-related subarachnoid hemorrhage (aSAH) patients with mild to moderate angiographic narrowing.
  
  
  METHODS
  We retrospectively studied 18 aSAH patients who had baseline and follow-up whole-brain CTP/computed tomography angiography. Thirty-one regions of interest/hemisphere at six levels were grouped by vascular territory. Arterial diameters were measured at the circle of Willis. The correlation between arterial diameter and change in CTP values, change in CTP in with and without DCI, and response to intra-arterial vasodilator therapy in DCI patients was evaluated.
  
  
  RESULTS
  There was correlation among the overall average cerebral blood flow (CBF; R=0.49, p<0.04), mean transit time (R=-0.48, p=0.04), and angiographic narrowing. In individual arterial territories, there was correlation between changes in CBF and arterial diameter in the middle cerebral artery (R=0.53, p=0.03), posterior cerebral artery (R=0.5, p=0.03), and anterior cerebral artery (R=0.54, p=0.02) territories. Prolonged mean transit time was correlated with arterial diameter narrowing in the middle cerebral artery territory (R=0.52, p=0.03). Patients with DCI tended to have serial worsening of CBF compared with those without DCI (p=0.055).
  
  
  CONCLUSIONS
  Our preliminary study demonstrates there is a correlation between mild to moderate angiographic narrowing and serial changes in perfusion in patients with aSAH. Patients developing DCI tended to have progressively worsening CBF compared with those not developing DCI.
authors.affiliation: 1Department of Diagnostic Medical Imaging,Neurointerventional & Neuroradiology Section,Ottawa Hospital,Ottawa,Ontario,Canada.
authors.forename: Cheemun
authors.initials: C
authors.lastname: Lum
authors.affiliation: 2Department of Medicine,Division of Neurology,Ottawa Hospital,Ottawa,Ontario,Canada.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hogan
authors.affiliation: 3Department of Surgery,Division of Neurosurgery,Ottawa Hospital,Ottawa,Ontario,Canada.
authors.forename: John
authors.initials: J
authors.lastname: Sinclair
authors.affiliation: 4Department of Medicine,Ottawa Hospital,Ottawa,Ontario,Canada.
authors.forename: Shane
authors.initials: S
authors.lastname: English
authors.affiliation: 3Department of Surgery,Division of Neurosurgery,Ottawa Hospital,Ottawa,Ontario,Canada.
authors.forename: Howard
authors.initials: H
authors.lastname: Lesiuk
authors.affiliation: 5Department of Radiology QEII Health Sciences Centre,Halifax,Halifax,Nova Scotia.
authors.forename: Jai
authors.initials: J
authors.lastname: Shankar
authors.affiliation: 1Department of Diagnostic Medical Imaging,Neurointerventional & Neuroradiology Section,Ottawa Hospital,Ottawa,Ontario,Canada.
authors.forename: Hala
authors.initials: H
authors.lastname: Ayoub
mesh_terms: D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D012189:Retrospective Studies; D013223:Statistics as Topic; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Aneurysm; CT perfusion; Subarachnoid hemorrhage