Neuroscience Research Australia, Randwick, NSW, Australia; School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
NMR Biomed. 2013 Nov;26(11):1387-94. doi: 10.1002/nbm.2964. Epub 2013 May 3.
Physiological and pathological changes to the anisotropic mechanical properties of skeletal muscle are still largely unknown, with only a few studies quantifying changes in vivo. This study used the noninvasive MR elastography (MRE) technique, in combination with diffusion tensor imaging (DTI), to measure shear modulus anisotropy in the human skeletal muscle in the lower leg. Shear modulus measurements parallel and perpendicular to the fibre direction were made in 10 healthy subjects in the medial gastrocnemius, soleus and tibialis anterior muscles. The results showed significant differences in the medial gastrocnemius (μ‖ = 0.86 ± 0.15 kPa; μ⊥ = 0.66 ± 0.19 kPa, P < 0.001), soleus (μ‖ = 0.83 ± 0.22 kPa; μ⊥ = 0.65 ± 0.13 kPa, P < 0.001) and the tibialis anterior (μ‖ = 0.78 ± 0.24 kPa; μ⊥ = 0.66 ± 0.16 kPa, P = 0.03) muscles, where the shear modulus measured in the direction parallel is greater than that measured in the direction perpendicular to the muscle fibres. No significant differences were measured across muscle groups. This study provides the first direct estimates of the anisotropic shear modulus in the triceps surae muscle group, and shows that the technique may be useful for the probing of mechanical anisotropy changes caused by disease, aging and injury.
骨骼肌各向异性力学性能的生理和病理变化在很大程度上仍然未知，只有少数研究定量测量了体内的变化。本研究使用无创性磁共振弹性成像（MRE）技术，结合扩散张量成像（DTI），测量小腿人体骨骼肌的剪切模量各向异性。在 10 名健康受试者的内侧比目鱼肌、比目鱼肌和胫骨前肌中，分别测量了与纤维方向平行和垂直的剪切模量。结果显示，在内侧比目鱼肌（μ‖=0.86±0.15kPa；μ⊥=0.66±0.19kPa，P<0.001）、比目鱼肌（μ‖=0.83±0.22kPa；μ⊥=0.65±0.13kPa，P<0.001）和胫骨前肌（μ‖=0.78±0.24kPa；μ⊥=0.66±0.16kPa，P=0.03）中，平行于纤维方向测量的剪切模量大于垂直于纤维方向测量的剪切模量。不同肌肉组之间无显著差异。本研究首次直接估计了小腿三头肌群的各向异性剪切模量，并表明该技术可能有助于探测疾病、衰老和损伤引起的机械各向异性变化。
