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Dynamic PCr and pH imaging of human calf muscles during exercise and recovery using 31 P gradient‐Echo MRI at 7 Tesla
Author(s) -
Schmid Albrecht Ingo,
Meyerspeer Martin,
Robinson Simon Daniel,
Goluch Sigrun,
Wolzt Michael,
Fiedler Georg Bernd,
Bogner Wolfgang,
Laistler Elmar,
Krššák Martin,
Moser Ewald,
Trattnig Siegfried,
Valkovič Ladislav
Publication year - 2016
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25822
Subject(s) - gradient echo , voxel , nuclear magnetic resonance , chemistry , phosphocreatine , temporal resolution , signal (programming language) , calf muscle , nuclear medicine , magnetic resonance imaging , energy metabolism , biomedical engineering , physics , medicine , computer science , radiology , quantum mechanics , programming language
Purpose Simultaneous acquisition of spatially resolved 31 P‐MRI data for evaluation of muscle specific energy metabolism, i.e., PCr and pH kinetics. Methods A three‐dimensional (3D) gradient‐echo sequence for multiple frequency‐selective excitations of the PCr and P i 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. Results Signal from anatomically matched regions of interest had sufficient signal‐to‐noise ratio to allow single‐acquisition PCr and pH quantification. The P i 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. Conclusion Simultaneous acquisition of PCr and P i 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.