title: MRI mapping of cerebrovascular reactivity using square wave changes in end-tidal PCO2.
abstract: Cerebrovascular reactivity can be quantified by correlating blood oxygen level dependent (BOLD) signal intensity with changes in end-tidal partial pressure of carbon dioxide (PCO2). Four 3-min cycles of high and low PCO2 were induced in three subjects, each cycle containing a steady PCO2 level lasting at least 60 sec. The BOLD signal closely followed the end-tidal PCO2. The mean MRI signal intensity difference between high and low PCO2 (i.e., cerebrovascular reactivity) was 4.0 +/- 3.4% for gray matter and 0.0 +/- 2.0% for white matter. This is the first demonstration of the application of a controlled reproducible physiologic stimulus, i.e., alternating steady state levels of PCO2, to the quantification of cerebrovascular reactivity.
authors.affiliation: Department of Anesthesia, University Health Network, University of Toronto, Toronto, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Vesely
authors.forename: H
authors.initials: H
authors.lastname: Sasano
authors.forename: G
authors.initials: G
authors.lastname: Volgyesi
authors.forename: R
authors.initials: R
authors.lastname: Somogyi
authors.forename: J
authors.initials: J
authors.lastname: Tesler
authors.forename: L
authors.initials: L
authors.lastname: Fedorko
authors.forename: J
authors.initials: J
authors.lastname: Grynspan
authors.forename: A
authors.initials: A
authors.lastname: Crawley
authors.forename: J A
authors.initials: JA
authors.lastname: Fisher
authors.forename: D
authors.initials: D
authors.lastname: Mikulis
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply*; D001931:Brain Mapping; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide