Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA.
Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, New York, USA.
Magn Reson Med. 2018 Feb;79(2):974-980. doi: 10.1002/mrm.26728. Epub 2017 May 30.
To develop a high temporal resolution imaging method that measures muscle-specific phosphocreatine (PCr) resynthesis time constant (τ ) and pH changes in muscles of the lower leg following exercise on a clinical 3T MRI scanner.
We developed a frequency-selective 3D non-Cartesian FLORET sequence to measure PCr with 17-mm nominal isotropic resolution (28 mm actual resolution) and 6-s temporal resolution to capture dynamic metabolic muscle activity. The sequence was designed to additionally collect inorganic phosphate spectra for pH quantification, which were localized using sensitivity profiles of individual coil elements. Nineteen healthy volunteers were scanned while performing a plantar flexion exercise on an in-house developed ergometer. Data were acquired with a dual-tuned multichannel coil array that enabled phosphorus imaging and proton localization for muscle segmentation.
After a 90-s plantar flexion exercise at 0.66 Hz with resistance set to 40% of the maximum voluntary contraction, τ was estimated at 22.9 ± 8.8 s (mean ± standard deviation) with statistical coefficient of determination r = 0.89 ± 0.05. The corresponding pH values after exercise were in the range of 6.9-7.1 in the gastrocnemius muscle.
The developed technique allows measurement of muscle-specific PCr resynthesis kinetics and pH changes following exercise, with a temporal resolution and accuracy comparable to that of single voxel P-MRS sequences. Magn Reson Med 79:974-980, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
开发一种高时间分辨率的成像方法，用于在临床 3T MRI 扫描仪上测量运动后小腿肌肉的肌特异性磷酸肌酸（PCr）再合成时间常数（τ）和 pH 值变化。
我们开发了一种频率选择的 3D 非笛卡尔 FLORET 序列，使用具有 17-mm 标称各向同性分辨率（实际分辨率为 28-mm）和 6-s 时间分辨率的序列来测量 PCr，以捕捉动态代谢肌肉活动。该序列旨在额外收集用于 pH 值定量的无机磷谱，这是通过单独线圈元件的灵敏度分布来定位的。19 名健康志愿者在内部开发的测力计上进行足底屈曲运动时接受了扫描。使用双调谐多通道线圈阵列采集数据，该阵列能够进行磷成像和质子定位以进行肌肉分割。
在以 0.66-Hz 的频率进行 90-s 的足底屈曲运动，阻力设置为最大自主收缩的 40%后，τ 估计为 22.9±8.8 s（平均值±标准偏差），统计系数 r 为 0.89±0.05。运动后的相应 pH 值在腓肠肌中为 6.9-7.1 之间。
所开发的技术允许测量运动后肌肉特异性 PCr 再合成动力学和 pH 值变化，具有与单像素 P-MRS 序列相当的时间分辨率和准确性。磁共振医学 79:974-980,2018. © 2017 国际磁共振学会。
