title: Organ-specific effects of oxygen and carbogen gas inhalation on tissue longitudinal relaxation times.
abstract: Molecular oxygen has been previously shown to shorten longitudinal relaxation time (T1) in the spleen and renal cortex, but not in the liver or fat. In this study, the magnitude and temporal evolution of this effect were investigated. Medical air, oxygen, and carbogen (95% oxygen/5% CO2) were administered sequentially in 16 healthy volunteers. T1 maps were acquired using spoiled gradient echo sequences (TR=3.5 ms, TE=0.9 ms, alpha=2 degrees/8 degrees/17 degrees) with six acquisitions on air, 12 on oxygen, 12 on carbogen, and six to 12 back on air. Mean T1 values and change in relaxation rate were compared between each phase of gas inhalation in the liver, spleen, skeletal muscle, renal cortex, and fat by one-way analysis of variance. Oxygen-induced T1-shortening occurred in the liver in fasted subjects (P<0.001) but not in non-fasted subjects (P=0.244). T1-shortening in spleen and renal cortex (both P<0.001) were greater than previously reported. Carbogen induced conflicting responses in different organs, suggesting a complex relationship with organ vasculature. Shortening of tissue T1 by oxygen is more pronounced and more complex than previously recognized. The effect may be useful as a biomarker of arterial flow and oxygen delivery to vascular beds.
authors.affiliation: Imaging Science and Biomedical Engineering, University of Manchester, and Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester, UK. james.o'connor@manchester.ac.uk
authors.forename: James P B
authors.initials: JP
authors.lastname: O'Connor
authors.forename: Alan
authors.initials: A
authors.lastname: Jackson
authors.forename: Giovanni A
authors.initials: GA
authors.lastname: Buonaccorsi
authors.forename: David L
authors.initials: DL
authors.lastname: Buckley
authors.forename: Caleb
authors.initials: C
authors.lastname: Roberts
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Watson
authors.forename: Sue
authors.initials: S
authors.lastname: Cheung
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: McGrath
authors.forename: Josephine H
authors.initials: JH
authors.lastname: Naish
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Rose
authors.forename: Paul M
authors.initials: PM
authors.lastname: Dark
authors.forename: Gordon C
authors.initials: GC
authors.lastname: Jayson
authors.forename: Geoff J M
authors.initials: GJ
authors.lastname: Parker
mesh_terms: D000005:Abdomen / Q000098:blood supply*; D000280:Administration, Inhalation; D000328:Adult; D001158:Arteries / Q000502:physiology; D002245:Carbon Dioxide / Q000008:administration & dosage*; D005215:Fasting / Q000502:physiology; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007672:Kidney Cortex / Q000098:blood supply; D008099:Liver / Q000098:blood supply; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D013154:Spleen / Q000098:blood supply; D050507:Subcutaneous Fat, Abdominal / Q000098:blood supply
chemical_list: D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen