title: The effect of dissolved oxygen on the relaxation rates of blood plasma: Implications for hyperoxia calibrated BOLD.
abstract: To determine the contribution of paramagnetic dissolved oxygen in blood plasma to blood-oxygenation-level-dependent (BOLD) signal changes in hyperoxic calibrated BOLD studies.
  
  
  
  Bovine blood plasma samples were prepared with partial pressures of oxygen (pO2) ranging from 110 to 600 mmHg. R1, R2, and R2*of the plasma with dissolved oxygen were measured using quantitative MRI sequences at 3 Tesla. Simulations were performed to predict the relative effects of dissolved oxygen and deoxyhemoglobin changes in hyperoxia calibrated BOLD.
  
  
  
  The relaxivities of dissolved oxygen in plasma were found to be r1,O2=1.97 ± 0.09 ×10-4s-1mmHg-1, r2,O2=2.3 ± 0.7 ×10-4s-1mmHg-1, and r2,O2*= 2.3 ± 0.7 ×10-4s-1mmHg-1. Simulations predict that neither the transverse nor longitudinal relaxation rates of dissolved oxygen contribute significantly to the BOLD signal during hyperoxia.
  
  
  
  During hyperoxia, the increases in R2and R2*of blood from dissolved oxygen in plasma are considerably less than the decreases in R2and R2*from venous deoxyhemoglobin. R1effects due to dissolved oxygen are also predicted to be negligible. As a result, dissolved oxygen in arteries should not contribute significantly to the hyperoxic calibrated BOLD signal. Magn Reson Med 76:1905-1911, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Ma
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.|Department of Radiology and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Avery J L
authors.initials: AJ
authors.lastname: Berman
authors.affiliation: Department of Radiology and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
authors.forename: G Bruce
authors.initials: GB
authors.lastname: Pike
mesh_terms: D000818:Animals; D016477:Artifacts; D001769:Blood / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002138:Calibration; D018496:Hyperoxia / Q000097:blood*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine
chemical_list: D010100:Oxygen
keywords: BOLD; dissolved oxygen; hyperoxia; relaxation rates