Magnetic resonance elastography (MRE) for measurement of muscle stiffness of the shoulder: feasibility with a 3T MRI system

Abstract

Background Magnetic resonance elastography (MRE) at 3T MR has the potential to improve the objective detection of skeletal muscle stiffness. Purpose To determine the feasibility of MRE using 3T MR for measurement of the stiffness of shoulder muscles in subjects. Material and Methods This study prospectively evaluated 16 healthy subjects (mean age, 29.8 years; range, 25-51 years). MRE was acquired with 3T MR through the use of a 2D-gradient-echo-based MRE sequence at two different excitation frequencies (90 and 120Hz). The mean stiffness values (MSV) of the trapezius and infraspinatus muscles were measured by two radiologists. Differences between the MSV in the x, y, and z motion-sensitization directions were assessed. Inter-observer agreement was also measured. Results The MSV of the trapezius muscle were 2.72kPa0.6 (SD) at 90Hz and 4.66kPa +/- 1.2 at 120Hz, while the MSV for the infraspinatus muscle were 3.2kPa +/- 0.52 at 90Hz and 4.38kPa +/- 0.92 at 120Hz. The MSV for both muscles were significantly higher at 120Hz than at 90Hz (P<0.05). The MSV in the three different directions were significantly different from each other in the infraspinatus muscle (P<0.05). Levels of inter-observer agreement regarding MSV were good to excellent for both the trapezius (intraclass correlation coefficient [ICC]=0.979-0.996) and infraspinatus muscles (ICC=0.614-0.943). Conclusion MRE at 3T is a feasible technique for the evaluation of shoulder muscle stiffness. Extended application of skeletal muscle MRE at 3T will contribute to the evaluation and treatment of skeletal muscle disorders.