title: Dynamic PCr and pH imaging of human calf muscles during exercise and recovery using (31) P gradient-Echo MRI at 7 Tesla.
abstract: Simultaneous acquisition of spatially resolved (31) P-MRI data for evaluation of muscle specific energy metabolism, i.e., PCr and pH kinetics.
  
  
  
  A three-dimensional (3D) gradient-echo sequence for multiple frequency-selective excitations of the PCr and Pi signals in an interleaved sampling scheme was developed and tested at 7 Tesla (T). The pH values were derived from the chemical shift-induced phase difference between the resonances. The achieved spatial resolution was ∼2 mL with image acquisition time below 6 s. Ten healthy volunteers were studied performing plantar flexions during the delay between (31) P-MRI acquisitions, yielding a temporal resolution of 9-10 s.
  
  
  
  Signal from anatomically matched regions of interest had sufficient signal-to-noise ratio to allow single-acquisition PCr and pH quantification. The Pi signal was clearly detected in voxels of actively exercising muscles. The PCr depletions were in gastrocnemius 42 ± 14% (medialis), 48 ± 17% (lateralis) and in soleus 20 ± 11%. The end exercise pH values were 6.74 ± 0.18 and 6.65 ± 0.27 for gastrocnemius medialis and lateralis, respectively, and 6.96 ± 0.12 for soleus muscle.
  
  
  
  Simultaneous acquisition of PCr and Pi images with high temporal resolution, suitable for measuring PCr and pH kinetics in exercise-recovery experiments, was demonstrated at 7T. This study presents a fast alternative to MRS for quantifying energy metabolism of posterior muscle groups of the lower leg. Magn Reson Med 75:2324-2331, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Albrecht Ingo
authors.initials: AI
authors.lastname: Schmid
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Meyerspeer
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.|Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria.
authors.forename: Simon Daniel
authors.initials: SD
authors.lastname: Robinson
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Sigrun
authors.initials: S
authors.lastname: Goluch
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Wolzt
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Georg Bernd
authors.initials: GB
authors.lastname: Fiedler
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.|Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bogner
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Elmar
authors.initials: E
authors.lastname: Laistler
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.|Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria.|Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Krššák
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Ewald
authors.initials: E
authors.lastname: Moser
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.|Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.affiliation: MR Centre of Excellence, Medical University of Vienna, Vienna, Austria.|Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.|Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria.|Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia.
authors.forename: Ladislav
authors.initials: L
authors.lastname: Valkovič
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000502:physiology; D010725:Phosphocreatine / Q000032:analysis / Q000378:metabolism*; D010759:Phosphorus Isotopes / Q000378:metabolism; D059629:Signal-To-Noise Ratio; D055815:Young Adult
chemical_list: D010759:Phosphorus Isotopes; D010725:Phosphocreatine
keywords: X-nuclei imaging; dynamic imaging; high energy phosphate; pH; skeletal muscle