title: Vessel-specific quantification of blood oxygenation with T2-relaxation-under-phase-contrast MRI.
abstract: OBJECTIVE
  Measurement of venous oxygenation (Yv) is a critical step toward quantitative assessment of brain oxygen metabolism, a key index in many brain disorders. The present study aims to develop a noninvasive, rapid, and reproducible method to measure Yv in a vessel-specific manner.
  
  
  BACKGROUND
  The method, T2-Relaxation-Under-Phase-Contrast MRI, utilizes complex subtraction of phase-contrast to isolate pure blood signal, applies nonslice-selective T2-preparation to measure T2, and converts T2 to oxygenation using a calibration plot.
  
  
  METHODS
  Following feasibility demonstration, several technical aspects were examined, including validation with an established global Yv technique, test-retest reproducibility, sensitivity to detect oxygenation changes due to hypoxia and caffeine challenges, applicability of echo-planar-imaging (EPI) acquisition to shorten scan duration, and ability to study veins with a caliber of 1-2 mm.
  
  
  RESULTS
  T2-Relaxation-Under-Phase-Contrast was able to simultaneously measure Yv in all major veins in the brain, including sagittal sinus, straight sinus, great vein, and internal cerebral vein. T2-Relaxation-Under-Phase-Contrast results showed an excellent agreement with the reference technique, high sensitivity to oxygenation changes, and test-retest variability of 3.5 ± 1.0%. The use of segmented-EPI was able to reduce the scan duration to 1.5 minutes. It was also feasible to study pial veins and deep veins.
  
  
  CONCLUSIONS
  T2-Relaxation-Under-Phase-Contrast MRI is a promising technique for vessel-specific oxygenation measurement.
authors.affiliation: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Department of Biomedical Engineering, University of Texas at Arlington, Arlington, Texas, USA.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Krishnamurthy
authors.forename: Peiying
authors.initials: P
authors.lastname: Liu
authors.forename: Yulin
authors.initials: Y
authors.lastname: Ge
authors.forename: Hanzhang
authors.initials: H
authors.lastname: Lu
mesh_terms: D000328:Adult; D002536:Cerebral Arteries / Q000378:metabolism*; 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; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D010100:Oxygen