title: Empirical model of human blood transverse relaxation at 3 T improves MRI T2oximetry.
abstract: We sought a human blood T2-oximetery calibration curve over the wide range of hematocrits commonly found in anemic patients applicable with T2relaxation under spin tagging (TRUST).
  
  
  
  Blood was drawn from five healthy control subjects. Ninety-three in vitro blood transverse relaxation (T2b) measurements were performed at 37°C over a broad range of hematocrits (10-55%) and oxygen saturations (14-100%) at 3 Tesla (T). In vivo TRUST was performed on 35 healthy African American control subjects and 11 patients with chronic anemia syndromes.
  
  
  
  1/T2rose linearly with hematocrit (r2= 0.96), for fully saturated blood. Upon desaturation, 1/T2rose linearly with the square of the oxygen extraction, (1-Y)2, and the slope was linearly proportional to hematocrit (r2= 0.88). The resulting bilinear model between 1/T2, (1-Y)2, and hematocrit had a combined r2of 0.96 and a coefficient of variation of 6.1%. Using the in vivo data, the bilinear model had significantly lower bias and variability than existing calibrations, particularly for low hematocrits. In vivo Bland Altman analysis demonstrated clinically relevant bias that was -6% (absolute saturation) for hematocrits near 30% and rose to + 6% for hematocrits near 45%.
  
  
  
  This work introduces a robust bilinear calibration model that should be used for MRI oximetry. Magn Reson Med 77:2364-2371, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA.|Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Bush
authors.affiliation: Division of Neonatology, Children's Hospital Los Angeles, Los Angeles, California, USA.|Department of Radiology, Children's Hospital Los Angeles, Los Angeles, California, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Borzage
authors.affiliation: Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA.
authors.forename: John
authors.initials: J
authors.lastname: Detterich
authors.affiliation: Division of Pulmonary, Children's Hospital Los Angeles, Los Angeles, California, USA.
authors.forename: Roberta M
authors.initials: RM
authors.lastname: Kato
authors.affiliation: Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Meiselman
authors.affiliation: Division of Hematology/Oncology, Children's Hospital Los Angeles, Los Angeles, California, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Coates
authors.affiliation: Division of Cardiology, Children's Hospital Los Angeles, Los Angeles, California, USA.|Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Wood
mesh_terms: D003198:Computer Simulation; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D010100:Oxygen
keywords: Blood Oxygenation; Blood Relaxometry; T2 Relaxation Under Spin Tagging; Transverse Relaxation