title: Proton magnetic resonance spectroscopy of skeletal muscle: a comparison of two quantitation techniques.
abstract: OBJECTIVE
  The aim of this study was to develop and compare two methods for quantification of metabolite concentrations in human skeletal muscle using phased-array receiver coils at 3T.
  
  
  METHODS
  Water suppressed and un-suppressed spectra were recorded from the quadriceps muscle (vastus medialis) in 8 healthy adult volunteers, and from a calibration phantom containing 69mM/L N-acetyl aspartate. Using the phantom replacement technique, trimethylamine specifically [TMA] and creatine [Cr] concentrations were estimated, and compared to those values obtained by using the water reference method.
  
  
  RESULTS
  Quadriceps [TMA] concentrations were 9.5±2.4 and 9.6±4.1mmol/kg wet weight using the phantom replacement and water referencing methods respectively, while [Cr] concentrations were 26.8±12.2 and 24.1±5.3mmol/kg wet weight respectively.
  
  
  CONCLUSIONS
  Reasonable agreement between water referencing and phantom replacement methods was found, although for [Cr] variation was significantly higher for the phantom replacement technique. The relative advantages and disadvantages of each approach are discussed.
authors.affiliation: Department of Radiation Oncology, Weill Cornell Medical College, New York, NY 10021, United States. Electronic address: xiw2007@med.cornell.edu.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Siemens Medical Solutions, Malvern, PA 19355, United States.
authors.forename: Nouha
authors.initials: N
authors.lastname: Salibi
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Fayad
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21205, United States.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Barker
mesh_terms: D000328:Adult; D000465:Algorithms; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D003198:Computer Simulation; D003401:Creatine / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008744:Methylamines / Q000378:metabolism*; D008954:Models, Biological; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D008744:Methylamines; D001224:Aspartic Acid; C000179:N-acetylaspartate; C023336:trimethylamine; D003401:Creatine
keywords: MR spectroscopy; Muscle; Phantom replacement; Quantitation