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Comparing localized and nonlocalized dynamic 31 P magnetic resonance spectroscopy in exercising muscle at 7T
Author(s) -
Meyerspeer Martin,
Robinson Simon,
Nabuurs Christine I.,
Scheenen Tom,
Schoisengeier Adrian,
Unger Ewald,
Kemp Graham J.,
Moser Ewald
Publication year - 2012
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.24205
Subject(s) - phosphocreatine , nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , chemistry , spectroscopy , magnetic resonance imaging , inorganic phosphate , creatine , phosphate , medicine , energy metabolism , physics , biochemistry , quantum mechanics , radiology
By improving spatial and anatomical specificity, localized spectroscopy can enhance the power and accuracy of the quantitative analysis of cellular metabolism and bioenergetics. Localized and nonlocalized dynamic 31 P magnetic resonance spectroscopy using a surface coil was compared during aerobic exercise and recovery of human calf muscle. For localization, a short echo time single‐voxel magnetic resonance spectroscopy sequence with adiabatic refocusing (semi‐LASER) was applied, enabling the quantification of phosphocreatine, inorganic phosphate, and pH value in a single muscle (medial gastrocnemius) in single shots ( T R = 6 s). All measurements were performed in a 7 T whole body scanner with a nonmagnetic ergometer. From a series of equal exercise bouts we conclude that: (a) with localization, measured phosphocreatine declines in exercise to a lower value (79 ± 7% cf. 53 ± 10%, P = 0.002), (b) phosphocreatine recovery shows shorter half time ( t 1/2 = 34 ± 7 s cf. t 1/2 = 42 ± 7 s, nonsignificant) and initial postexercise phosphocreatine resynthesis rate is significantly higher (32 ± 5 mM/min cf. 17 ± 4 mM/min, P = 0.001) and (c) in contrast to nonlocalized 31 P magnetic resonance spectroscopy, no splitting of the inorganic phosphate peak is observed during exercise or recovery, just an increase in line width during exercise. This confirms the absence of contaminating signals originating from weaker‐exercising muscle, while an observed inorganic phosphate line broadening most probably reflects variations across fibers in a single muscle. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.