title: Oxygen challenge magnetic resonance imaging in healthy human volunteers.
abstract: Oxygen challenge imaging involves transient hyperoxia applied during deoxyhaemoglobin sensitive (T2*-weighted) magnetic resonance imaging and has the potential to detect changes in brain oxygen extraction. In order to develop optimal practical protocols for oxygen challenge imaging, we investigated the influence of oxygen concentration, cerebral blood flow change, pattern of oxygen administration and field strength on T2*-weighted signal. Eight healthy volunteers underwent multi-parametric magnetic resonance imaging including oxygen challenge imaging and arterial spin labelling using two oxygen concentrations (target FiO2of 100 and 60%) administered consecutively (two-stage challenge) at both 1.5T and 3T. There was a greater signal increase in grey matter compared to white matter during oxygen challenge (p < 0.002 at 3T, P < 0.0001 at 1.5T) and at FiO2= 100% compared to FiO2= 60% in grey matter at both field strengths (p < 0.02) and in white matter at 3T only (p = 0.0314). Differences in the magnitude of signal change between 1.5T and 3T did not reach statistical significance. Reduction of T2*-weighted signal to below baseline, after hyperoxia withdrawal, confounded interpretation of two-stage oxygen challenge imaging. Reductions in cerebral blood flow did not obscure the T2*-weighted signal increases. In conclusion, the optimal protocol for further study should utilise target FiO2= 100% during a single oxygen challenge. Imaging at both 1.5T and 3T is clinically feasible.
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Queen Elizabeth University Hospital Glasgow, Glasgow.
authors.forename: Krishna A
authors.initials: KA
authors.lastname: Dani
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Queen Elizabeth University Hospital Glasgow, Glasgow.
authors.forename: Fiona C
authors.initials: FC
authors.lastname: Moreton
authors.affiliation: Department of Neuroradiology, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow.
authors.forename: Celestine
authors.initials: C
authors.lastname: Santosh
authors.affiliation: Department of Clinical Physics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow.
authors.forename: Rosario
authors.initials: R
authors.lastname: Lopez
authors.affiliation: Department of Clinical Physics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow.
authors.forename: David
authors.initials: D
authors.lastname: Brennan
authors.affiliation: University of Applied Sciences Munich, School of Applied Sciences and Mechatronics, München.
authors.forename: Christian
authors.initials: C
authors.lastname: Schwarzbauer
authors.affiliation: Department of Anaesthetics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow.
authors.forename: Colin
authors.initials: C
authors.lastname: Goutcher
authors.affiliation: Department of Anaesthetics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow.
authors.forename: Kevin
authors.initials: K
authors.lastname: O'Hare
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow.
authors.forename: I Mhairi
authors.initials: IM
authors.lastname: Macrae
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Queen Elizabeth University Hospital Glasgow, Glasgow keith.muir@glasgow.ac.uk.
authors.forename: Keith W
authors.initials: KW
authors.lastname: Muir
mesh_terms: D000328:Adult; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D066128:Gray Matter / Q000000981:diagnostic imaging; D064368:Healthy Volunteers; D006801:Humans; D018496:Hyperoxia / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008722:Methods; D010100:Oxygen / Q000378:metabolism; D013113:Spin Labels; D066127:White Matter / Q000000981:diagnostic imaging
chemical_list: D013113:Spin Labels; D010100:Oxygen
keywords: Magnetic resonance imaging; cerebral blood flow; hyperoxia; metabolism; oxygen challenge imaging