Galbán Craig J, Maderwald Stefan, Uffmann Kai, Ladd Mark E
Department of Diagnostic and Interventional Radiology, University Hospital Essen, Hufelandstrasse 55, D-45122 Essen, Germany.
NMR Biomed. 2005 Dec;18(8):489-98. doi: 10.1002/nbm.975.
The diffusive properties of adjacent muscles at rest were evaluated in male (n = 12) and female (n = 12) subjects using diffusion tensor imaging (DTI). The principle, second and third eigenvalues, trace of the diffusion tensor [Tr(D)], and two anisotropic parameters, ellipsoid eccentricity (e) and fractional anisotropy (FA), of various muscles in the human calf were calculated from the diffusion tensor. Seven muscles were investigated in this study from images acquired of the left calf: the soleus, lateral gastrocnemius, medial gastrocnemius, posterior tibialis, anterior tibialis, extensor digitorum longus and peroneus longus. A mathematical model was also derived that relates the eigenvalues of the diffusion tensor to the muscle fiber volume fraction, which is defined as the volume of muscle fibers within a well-defined arbitrary muscle volume. Females on average had higher eigenvalues and Tr(D) compared with males, with the majority of muscles being statistically different between the sexes. In contrast, males on average had higher e and FA than females, with the large plantar flexors--soleus, lateral gastrocnemius, and medial gastrocnemius--producing statistically different results. The behavior of the mathematical model for variations in fiber volume fraction produced similar trends to those seen when the experimental data were fit to the model. The model predicts that a larger volume fraction of skeletal muscle in males is devoted to fibers than in females, but the true underlying source of the gender discrepancy remains unclear. Although the model does not fully account for other transport processes, it does provide some insight into the limiting factors that affect the diffusion of water in skeletal muscle measured by DTI.
利用扩散张量成像（DTI）对12名男性和12名女性受试者静息状态下相邻肌肉的扩散特性进行了评估。从小腿扩散张量计算出人体小腿各肌肉的扩散张量的主、第二和第三特征值、扩散张量迹[Tr(D)]以及两个各向异性参数，即椭球偏心率（e）和分数各向异性（FA）。本研究从左小腿图像中选取了七块肌肉进行研究：比目鱼肌、腓骨外侧肌、腓骨内侧肌、胫后肌、胫前肌、趾长伸肌和腓骨长肌。还推导了一个数学模型，该模型将扩散张量的特征值与肌纤维体积分数相关联，肌纤维体积分数定义为在明确界定的任意肌肉体积内的肌纤维体积。与男性相比，女性的特征值和Tr(D)平均较高，大多数肌肉在性别之间存在统计学差异。相反，男性的e和FA平均高于女性，大型跖屈肌——比目鱼肌、腓骨外侧肌和腓骨内侧肌——产生了统计学上不同的结果。当将纤维体积分数变化的数学模型行为与实验数据拟合到该模型时所观察到的趋势相似。该模型预测，男性骨骼肌中用于纤维的体积分数比女性大，但性别差异的真正潜在来源仍不清楚。尽管该模型没有完全考虑其他传输过程，但它确实为影响DTI测量的骨骼肌中水扩散的限制因素提供了一些见解。
