Localized semi-LASER dynamic (31)P magnetic resonance spectroscopy of the soleus during and following exercise at 7 T

• Published in: Magma (New York, N.Y.) Vol. 28; no. 5; p. 493
• Main Authors: Fiedler, Georg B, Meyerspeer, Martin, Schmid, Albrecht I, Goluch, Sigrun, Schewzow, Kiril, Laistler, Elmar, Mirzahosseini, Arash, Niess, Fabian, Unger, Ewald, Wolzt, Michael, Moser, Ewald
• Format: Journal Article
• Language: English
• Published: Germany 01.10.2015
• Subjects: Equipment Design; Equipment Failure Analysis; Exercise - physiology; Female; Humans; Lasers; Magnetic Resonance Spectroscopy - instrumentation; Male; Muscle, Skeletal - physiology; Phosphocreatine - metabolism; Phosphorus Isotopes - pharmacokinetics; Reproducibility of Results; Sensitivity and Specificity; Young Adult; Phosphocreatine; In vivo NMR spectroscopy; Soleus muscle; Physical exertion; Skeletal muscle
• ISSN: 1352-8661
• DOI: 10.1007/s10334-015-0484-5

This study demonstrates the applicability of semi-LASER localized dynamic (31)P MRS to deeper lying areas of the exercising human soleus muscle (SOL). The effect of accurate localization and high temporal resolution on data specificity is investigated. To achieve high signal-to-noise ratio (SNR) at a temporal resolution of 6 s, a custom-built human calf coil array was used at 7T. The kinetics of phosphocreatine (PCr) and intracellular pH were quantified separately in SOL and gastrocnemius medialis (GM) muscle of nine volunteers, during rest, plantar flexion exercise, and recovery. The average SNR of PCr at rest was [Formula: see text] in SOL ([Formula: see text] in GM). End exercise PCr depletion in SOL ([Formula: see text] %) was far lower than in GM ([Formula: see text] %). The pH in SOL increased rapidly and, in contrast to GM, remained elevated until the end of exercise. (31)P MRS in single-shots every 6 s localized in the deeper-lying SOL enabled quantification of PCr recovery times at low depletions and of fast pH changes, like the initial rise. Both high temporal resolution and accurate spatial localization improve specificity of Pi and, thus, pH quantification by avoiding multiple, and potentially indistinguishable sources for changing the Pi peak shape.