Wave attenuation as a measure of muscle quality as measured by magnetic resonance elastography: initial results

Advances in imaging technologies such as magnetic resonance elastography (MRE) have allowed researchers to gain insights into muscle function in vivo. MRE has been used to examine healthy and diseased muscle by calculating shear modulus. However, additional information can be measured from visualizing a mechanical wave as it passes through a tissue. One such measurable quantity is wave attenuation. The purpose of this study was to determine if a simple measure of wave attenuation could be used to distinguish between healthy and diseased muscle. Twenty seven subjects (14 healthy controls, 7 hyperthyroid myopathy patients, 6 myositis patients) participated in this study. Wave amplitude was determined along a linear profile through the center of the muscle, and an exponential decay curve was fit to the data. This measure was able to find significant differences in attenuation between healthy and diseased muscle. Furthermore, four hyperthyroid myopathy subjects who were tested following treatment all showed improvement by this measure. A likely reason for patients with hyperthyroid myopathy and myositis behaving similarly is that this measurement may reflect similar changes in the muscle extracellular matrix. In addition to modulus, attenuation seems to be an important parameter to measure in skeletal muscle. Further research is needed to investigate other potential measures of attenuation as well as examining other potential measures that can be found from visualizing wave propagation. Future studies should also include muscle biopsies to confirm that the changes seen are as a result of changes in extracellular matrix structure.