title: Non-invasive multiparametric qBOLD approach for robust mapping of the oxygen extraction fraction.
abstract: BACKGROUND
  The quantitative blood oxygenation level-dependent (qBOLD) method has not become clinically established yet because long acquisition times are necessary to achieve an acceptable certainty of the parameter estimates. In this work, a non-invasive multiparametric (nimp) qBOLD approach based on a simple analytical model is proposed to facilitate robust oxygen extraction fraction (OEF) mapping within clinically acceptable acquisition times by using separate measurements.
  
  
  METHODS
  The protocol consisted of a gradient-echo sampled spin-echo sequence (GESSE), a T2-weighted Carr-Purcell-Meiboom-Gill (CPMG) sequence, and a T2(*)-weighted multi-slice multi-echo gradient echo (MMGE) sequence. The GESSE acquisition time was less than 5 minutes and the extra measurement time for CPMG/MMGE was below 2 minutes each. The proposed nimp-qBOLD approach was validated in healthy subjects (N = 5) and one patient.
  
  
  RESULTS
  The proposed nimp-qBOLD approach facilitated more robust OEF mapping with significantly reduced inter- and intra-subject variability compared to the standard qBOLD method. Thereby, an average OEF in all subjects of 27±2% in white matter (WM) and 29±2% in gray matter (GM) using the nimp-qBOLD method was more stable compared to 41±10% (WM) and 46±10% (GM) with standard qBOLD. Moreover, the spatial variance in the image slice (i.e. standard deviation divided by mean) was on average reduced from 35% to 25%. In addition, the preliminary results of the patient are encouraging.
  
  
  CONCLUSIONS
  The proposed nimp-qBOLD technique provides a promising tool for robust OEF mapping within clinically acceptable acquisition times and could therefore provide an important contribution for analyzing tumors or monitoring the success of radio and chemo therapies.
authors.affiliation: Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany. Electronic address: sebastian.domsch@medma.uni-heidelberg.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Domsch
authors.affiliation: Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Moritz B
authors.initials: MB
authors.lastname: Mie
authors.affiliation: Department of Radiation Oncology, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Wenz
authors.affiliation: Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Lothar R
authors.initials: LR
authors.lastname: Schad
mesh_terms: D000328:Adult; D000465:Algorithms; D001931:Brain Mapping / Q000379:methods*; D002536:Cerebral Arteries / Q000033:anatomy & histology* / Q000378:metabolism*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen
keywords: GESSE; Gewebe-Modell; Quantitative BOLD; Quantitative BOLD-Bildgebung (qBOLD); Sauerstoff-Extraktionskoeffizient; oxygen extraction fraction; tissue model