Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Ma 02115, USA.
Acad Radiol. 2011 Jul;18(7):917-23. doi: 10.1016/j.acra.2011.02.014. Epub 2011 May 4.
Heterogeneity of skeletal muscle structure, composition, and perfusion results in spatial differences in oxidative function between muscles and muscle regions. The simultaneous measurement of the postexercise phosphocreatine (PCr) recovery rate across all muscles of a human limb cross-section may provide new insights into normal physiology and disease states. The objective of this work was to assess the feasibility of acquiring PCr rapid acquisition with relaxation enhancement (RARE) images with sufficient temporal and spatial resolution to accurately measure PCr recovery kinetics in a cross-section of a human limb.
One normal subject performed a finger exercise until fatigued. At cessation of exercise surface coil localized pulse-and-acquire phosphorus-31 MR spectra ((31)P- magnetic resonance spectroscopy [MRS]) of the forearm were acquired at 6 S intervals for 4 minutes. The exercise protocol was repeated 7 days later and axial PCr RARE images of the forearm were acquired following exercise with 5.6 cm(3) voxels at 6-second intervals for 4 minutes.
The PCr recovery time constants for the PCr RARE and (31)P-MRS measurements were 91.0 and 91.1 seconds, respectively, based on a monoexponential fit. A Pearson correlation test showed that the PCr recovery data that resulted from the RARE PCr imaging were highly correlated with the data resulting from the (31)P-MRS (r = 0.91, P < .0001).
Data from selected regions of RARE PCr images acquired at 6-second intervals compare well to those acquired using surface coil (31)P MR spectroscopy and can provide an accurate assessment of PCr recovery kinetics.
骨骼肌肉结构、组成和灌注的异质性导致肌肉和肌肉区域之间的氧化功能存在空间差异。同时测量人体肢体横截面上所有肌肉的磷酸肌酸（PCr）恢复率，可以为正常生理和疾病状态提供新的见解。本研究的目的是评估使用弛豫增强（RARE）技术获取 PCr 快速获取图像的可行性，以获得足够的时间和空间分辨率来准确测量人体肢体横截面上的 PCr 恢复动力学。
一名正常受试者进行手指运动至疲劳。运动停止后，在 6 S 的间隔内，用表面线圈对前臂进行 4 分钟的局部脉冲采集磷-31MR 光谱（（31）P-MR 光谱）。7 天后重复运动方案，在运动后用 5.6 cm3 体素以 6 秒的间隔采集前臂的轴向 PCr RARE 图像，持续 4 分钟。
基于单指数拟合，PCr RARE 和（31）P-MRS 测量的 PCr 恢复时间常数分别为 91.0 和 91.1 秒。Pearson 相关检验显示，RARE PCr 成像的 PCr 恢复数据与（31）P-MRS 数据高度相关（r=0.91，P<0.0001）。
在 6 秒的间隔内采集 RARE PCr 图像的选定区域的数据与使用表面线圈（31）P-MR 光谱采集的数据非常吻合，可以准确评估 PCr 恢复动力学。
