Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
Magn Reson Med. 2012 Dec;68(6):1713-23. doi: 10.1002/mrm.24205. Epub 2012 Feb 14.
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.
通过提高空间和解剖学特异性，局部光谱可以提高细胞代谢和生物能量学定量分析的能力和准确性。在有氧运动和人小腿肌肉恢复期间，使用表面线圈比较了局部和非局部动态（31）P 磁共振波谱。对于定位，应用了具有绝热重聚焦（半-LASER）的短回波时间单体磁共振波谱序列，从而能够在单次拍摄中（T（R）= 6 s）对单个肌肉（内侧腓肠肌）中的磷酸肌酸，无机磷酸盐和 pH 值进行定量。所有测量均在具有非磁性测力计的 7 T 全身扫描仪中进行。从一系列相等的运动回合中，我们得出结论：（a）通过定位，运动中测量的磷酸肌酸下降到较低的值（79 ± 7％与 53 ± 10％相比，P = 0.002），（b）磷酸肌酸恢复的半衰期（t（1/2）= 34 ± 7 s 与 t（1/2）= 42 ± 7 s 相比）较短，且初始运动后磷酸肌酸再合成率明显更高（32 ± 5 mM / min 与 17 ± 4 mM / min 相比，P = 0.001），（c）与非局部（31）P 磁共振波谱相反，在运动或恢复过程中均未观察到无机磷酸盐峰的分裂，只是在运动过程中峰线变宽。这证实了不存在源自较弱运动肌肉的污染信号，而观察到的无机磷酸盐线宽变宽很可能反映了单个肌肉中纤维之间的变化。
