Yanagisawa Osamu, Shimao Daisuke, Maruyama Katsuya, Nielsen Matthew, Irie Takeo, Niitsu Mamoru
Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama 359-1192, Japan.
Magn Reson Imaging. 2009 Jan;27(1):69-78. doi: 10.1016/j.mri.2008.05.011. Epub 2008 Jul 22.
To evaluate the apparent diffusion coefficient (ADC) of skeletal muscle based on signal intensity (SI) attenuation vs. increasing b values and to determine ADC differences in skeletal muscles between genders, age groups and muscles.
Diffusion-weighted images (b values in the range of 0-750 s/mm2 at increments of 50 s/mm2) of the ankle dorsiflexors (116 subjects) and the erector spinae muscles (86 subjects) were acquired with a 1.5-T MR device. From the two different slopes obtained in SI vs. b-value logarithmic plots, ADCb0-50 (b values=0 and 50 s/mm2) reflected diffusion and perfusion, while ADCb50-750 (b values in the range of 50-750 s/mm2 at increments of 50 s/mm2) approximated the true diffusion coefficient. Moreover, to evaluate whether this b-value combination is appropriate for assessing the flow component within muscles, diffusion-weighted images of the ankle dorsiflexors (10 subjects) were obtained before and during temporal arterial occlusion.
ADCb0-50 and ADCb50-750 were found to be 2.64x10(-3) and 1.44x10(-3) mm2/s in the ankle dorsiflexors, and 3.02x10(-3) and 1.49x10(-3) mm2/s in the erector spinae muscles, respectively. ADCb0-50 was significantly higher than ADCb50-750 in each muscle (P<.01). The erector spinae muscles showed significantly higher ADC values than the ankle dorsiflexors (P<.01). However, for each muscle, there were few significant gender- and age-related ADC differences. Following temporal occlusion, ADCb0-50 of the ankle dorsiflexors decreased significantly from 2.49 to 1.6x10(-3) mm2/s (P<.01); however, ADCb50-750 showed no significant change.
Based on the SI attenuation pattern, muscle ADC could be divided into ADC that reflects both diffusion and perfusion, and ADC that approximates a true diffusion coefficient. There were significant differences in ADC of functionally distinct muscles. However, we barely found any gender- or age-related ADC differences for each muscle.
基于信号强度（SI）衰减与增加的b值来评估骨骼肌的表观扩散系数（ADC），并确定不同性别、年龄组和肌肉之间骨骼肌的ADC差异。
使用1.5-T MR设备获取踝背屈肌（116名受试者）和竖脊肌（86名受试者）的扩散加权图像（b值范围为0 - 750 s/mm²，增量为50 s/mm²）。从SI与b值对数图中获得的两个不同斜率来看，ADCb0 - 50（b值 = 0和50 s/mm²）反映扩散和灌注，而ADCb50 - 750（b值范围为50 - 750 s/mm²，增量为50 s/mm²）近似于真实扩散系数。此外，为了评估这种b值组合是否适合评估肌肉内的血流成分，在颞动脉闭塞前和闭塞期间获取了踝背屈肌（10名受试者）的扩散加权图像。
踝背屈肌的ADCb0 - 50和ADCb50 - 750分别为2.64×10⁻³和1.44×10⁻³ mm²/s，竖脊肌的分别为3.02×10⁻³和1.49×10⁻³ mm²/s。每块肌肉中，ADCb0 - 50均显著高于ADCb50 - 750（P <.01）。竖脊肌的ADC值显著高于踝背屈肌（P <.01）。然而，对于每块肌肉，与性别和年龄相关的ADC差异不显著。颞动脉闭塞后，踝背屈肌的ADCb0 - 50从2.49显著降至1.6×10⁻³ mm²/s（P <.01）；然而，ADCb50 - 750无显著变化。
基于SI衰减模式，肌肉ADC可分为反映扩散和灌注的ADC以及近似真实扩散系数的ADC。功能不同的肌肉在ADC上存在显著差异。然而，我们几乎未发现每块肌肉在性别或年龄方面与ADC相关的差异。
