title: Mean transit time as an index of cerebral perfusion pressure in experimental systemic hypotension.
abstract: Early diagnosis of cerebrovascular disease requires the accurate identification of brain regions with compromised cerebral perfusion pressure (CPP). Current clinical measures of CPP are invasive and lack regional information. Dynamic contrast-enhanced imaging provides a means of looking at regional cerebral hemodynamics. The purpose of this study was to determine if any of the parameters associated with dynamic contrast-enhanced imaging could be used as an index for CPP under graded systemic hypotension in a rabbit model. Cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT), and cerebrovascular reserve (CVR) were measured using Computed Tomography Perfusion in three groups: normotensive (n = 14), mild hypotensive (n = 9), and moderate hypotensive (n = 6). MTT demonstrated the strongest correlation with CPP (ρ = -0.642, P < 0.05). CBF was the only other parameter to demonstrate a statistically significant correlation (ρ = 0.575, P < 0.05). CVR is gaining momentum for diagnosing cerebrovascular disease; however, the technique requires patients to be given a hemodynamic challenge, which could aggravate symptoms and even trigger stroke. The results of this study suggest that the use of MTT, not requiring hemodynamic manipulation, is more sensitive to subtle changes in CPP, as would occur in the early stages of cerebrovascular disease.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, PO Box 5015, 100 Perth Drive, London, Ontario N6A 5K8, Canada.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Murphy
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Tichauer
authors.forename: Louise
authors.initials: L
authors.lastname: Sun
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Chen
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000098:blood supply* / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D004195:Disease Models, Animal; D006973:Hypertension / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007427:Intracranial Pressure / Q000187:drug effects; D008297:Male; D011817:Rabbits; D015203:Reproducibility of Results; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D000086:Acetazolamide