title: Test-retest analysis of multiple31P magnetization exchange pathways using asymmetric adiabatic inversion.
abstract: A31P-MR inversion transfer (IT) method with a short adiabatic inversion pulse is proposed and its test-retest reliability was evaluated for two spectral fitting strategies.
  
  
  
  Assessment in a test-retest design (3 Tesla, vastus muscles, 12 healthy volunteers, 14 inversion times, 22 ms asymmetric adiabatic inversion pulse, adiabatic excitation); spectral fitting in Fitting Tool for Interrelated Arrays of Datasets (FitAID) and Java Magnetic Resonance User Interface (jMRUI); least squares solution of the Bloch-McConnell-Solomon matrix formalism including all 14 measured time-points with equal weighting.
  
  
  
  The cohort averages of k[PCr→γ-ATP] (phosphocreatine, PCr; adenosine triphosphate, ATP) are 0.246 ± 0.050s-1versus 0.254 ± 0.050s-1, and k[Pi→γ-ATP] 0.086 ± 0.033s-1versus 0.066 ± 0.034s-1(average ± standard deviation, jMRUI versus FitAID). Coefficients of variation of the differences between test and retest are lowest (9.5%) for k[PCr→γ-ATP] fitted in FitAID, larger (15.2%) for the fit in jMRUI, and considerably larger for k[Pi→γ-ATP] fitted in FitAID (43.4%) or jMRUI (47.9%). The beginning of the IT effect can be observed with magnetizations above 92% for noninverted lines while inversion of the ATP resonances is better than -72%.
  
  
  
  The performance of the asymmetric adiabatic pulse allows an accurate observation of IT effects even in the early phase; the least squares fit of the Bloch-McConnell-Solomon matrix formalism is robust; and the type of spectral fitting can influence the results significantly. Magn Reson Med 78:33-39, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Clinical Research and Department of Radiology, University of Bern, Switzerland.|Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Pouymayou
authors.affiliation: Department of Clinical Research and Department of Radiology, University of Bern, Switzerland.
authors.forename: Tania
authors.initials: T
authors.lastname: Buehler
authors.affiliation: Department of Clinical Research and Department of Radiology, University of Bern, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Kreis
authors.affiliation: Department of Clinical Research and Department of Radiology, University of Bern, Switzerland.
authors.forename: Chris
authors.initials: C
authors.lastname: Boesch
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods*; D018482:Muscle, Skeletal / Q000378:metabolism*; D015588:Observer Variation; D010725:Phosphocreatine / Q000031:analogs & derivatives* / Q000378:metabolism; D010758:Phosphorus / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014018:Tissue Distribution
chemical_list: D010725:Phosphocreatine; D010758:Phosphorus; C025403:phosphocreatinine
keywords: 31P MRS; ATP synthesis; creatine kinase; inversion transfer; skeletal muscle