Heers Guido, Jenkyn Thomas, Dresner M Alex, Klein Marc-Oliver, Basford Jeffrey R, Kaufman Kenton R, Ehman Richard L, An Kai-Nan
Orthopedic Biomechanics Laboratory, Mayo Clinic/Mayo Foundation, 200 First Street SW, Rochester, MN 55905, USA.
Clin Biomech (Bristol). 2003 Jul;18(6):537-42. doi: 10.1016/s0268-0033(03)00070-6.
To non-invasively determine muscle activity.
A correlation analysis study.
Electromyography is traditionally used to measure the electrical activity of a muscle and can be used to estimate muscle contraction intensity. This approach, however, is limited not only in terms of the volume of tissue that can be monitored, but must be invasive if deep lying muscles are studied. We wished to avoid these limitations and used magnetic resonance elastography in an attempt to non-invasively determine muscle activity. This novel approach uses a conventional MRI system. However, in addition to the imaging gradients, an oscillating, motion sensitizing field gradient is applied to detect mechanical waves that have been generated within the tissue. The wavelength correlates with the stiffness of the muscle and hence with the activity of the muscle.
Six volunteers (mean age: 30.1 years, range: 27-36 years) without orthopedic or neuromuscular abnormalities, lay supine with their legs within the coil of a MRI scanner. The wavelengths of mechanically generated shear waves in the tibialis anterior, medial and lateral head of the gastrocnemius and the soleus were measured as the subjects resisted ankle plantar-flexing (8.2 and 16.4 nm) and dorsi-flexing (20.2 and 40.4 nm) moments. The findings were then compared to EMG data collected under the same loading conditions.
Magnetic resonance elastography wavelengths were linearly correlated to the muscular activity as defined by electromyography. (TA, R(2)=0.89, P=0.02; MG, R(2)=0.82, P=0.05; LG, R(2)=0.88, P=0.03; S, R(2)=0.90, P=0.02)
Magnetic resonance elastography may be a promising tool for the non-invasive determination of muscle activity.
Magnetic resonance elastography has potential as the basis for a new non-invasive approach to study in vivo muscle function.
非侵入性地测定肌肉活动。
一项相关性分析研究。
传统上，肌电图用于测量肌肉的电活动，并可用于估计肌肉收缩强度。然而，这种方法不仅在可监测的组织体积方面存在局限性，而且如果研究深层肌肉则必须采用侵入性操作。我们希望避免这些局限性，因此使用磁共振弹性成像来尝试非侵入性地测定肌肉活动。这种新方法使用传统的MRI系统。然而，除了成像梯度外，还应用了一个振荡的、运动敏感场梯度来检测在组织内产生的机械波。波长与肌肉的硬度相关，从而与肌肉的活动相关。
6名无骨科或神经肌肉异常的志愿者（平均年龄：30.1岁，范围：27 - 36岁）仰卧，双腿置于MRI扫描仪的线圈内。在受试者抵抗踝关节跖屈（8.2和16.4纳米）和背屈（20.2和40.4纳米）力矩时，测量胫前肌、腓肠肌内侧头、外侧头和比目鱼肌中机械产生的剪切波的波长。然后将这些结果与在相同负荷条件下收集的肌电图数据进行比较。
磁共振弹性成像波长与肌电图定义的肌肉活动呈线性相关。（胫前肌，R(2)=0.89，P = 0.02；腓肠肌内侧头，R(2)=0.82，P = 0.05；腓肠肌外侧头，R(2)=0.88，P = 0.03；比目鱼肌，R(2)=0.90，P = 0.02）
磁共振弹性成像可能是一种用于非侵入性测定肌肉活动的有前景的工具。
磁共振弹性成像有潜力作为一种研究体内肌肉功能的新的非侵入性方法的基础。
