title: Simultaneous measurement of tissue oxygen level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) effects in abdominal tissue oxygenation level studies.
abstract: OBJECTIVE
  To assess oxygenation in abdominal organs with magnetic resonance imaging (MRI), a novel approach is presented to simultaneously measure both T1 - and T2*-maps serially during a single dynamic MRI scan in response to an oxygen challenge.
  
  
  METHODS
  The proposed acquisition scheme consists of a multishot multiecho gradient echo planar imaging sequence (ms-GEPI) interleaved with a multishot inversion recovery echo planar imaging (ms-IR-EPI) sequence. Respiratory motion compensation was accomplished with standard belt triggering and by acquiring all image data at the same phase of expiration. This respiratory-triggered, free-breathing, interleaved tissue oxygenation level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) acquisition technique was validated on phantoms and seven healthy volunteers in response to an oxygen challenge.
  
  
  RESULTS
  Measurements of relaxation times both in vitro and in vivo were in good agreement with those obtained using conventional pulse sequences and reported in the literature. The interleaved sequence was able to measure oxygen-induced relaxation time changes in human abdominal organs.
  
  
  CONCLUSIONS
  The free-breathing respiratory-triggered interleaved T1 and T2* sequence successfully provided relaxation time maps of abdominal organs in a dynamic scan without the need for image registration. The simultaneous monitoring of tissue and blood oxygenation improves time efficiency and should enhance studies comparing dynamic T1 and T2* data within the abdomen.
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Yao
authors.initials: Y
authors.lastname: Ding
authors.forename: Ralph P
authors.initials: RP
authors.lastname: Mason
authors.forename: Roderick W
authors.initials: RW
authors.lastname: McColl
authors.forename: Qing
authors.initials: Q
authors.lastname: Yuan
authors.forename: Rami R
authors.initials: RR
authors.lastname: Hallac
authors.forename: Robert D
authors.initials: RD
authors.lastname: Sims
authors.forename: Paul T
authors.initials: PT
authors.lastname: Weatherall
mesh_terms: D000005:Abdomen / Q000502:physiology*; D000328:Adult; D000465:Algorithms; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage / Q000493:pharmacokinetics*; D010101:Oxygen Consumption / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014781:Viscera / Q000187:drug effects / Q000378:metabolism*
chemical_list: D010100:Oxygen
keywords: BOLD; TOLD; kidney; oxygen challenge; spleen