Thigh muscle stiffness assessed with magnetic resonance elastography in hyperthyroid patients before and after medical treatment

Purpose: To measure the stiffness of the vastus medialis (VM) in hyperthyroid patients before and after treatment. Materials and Methods: A total of five healthy euthyroid patients and five hyperthyroid patients were tested using magnetic resonance elastography (MRE), which involves the induction of shear waves in the thigh muscles using a pneumatic driver at 90 Hz. Results: Among the pretreatment hyperthyroid cohort a lower stiffness was found when the muscle was relaxed (2.11 +/- 0.61 kPa) compared the stiffness following treatment of hyperthyroidism (5.52 +/- 1.52 kPa), which was accompanied by an improvement in the contractile function of the VM. Pretreatment muscle stiffness was also less than that of age matched healthy volunteers (4.56 +/- 0.40 kPa). The behavior of the waves was sensitive to the stage of this myopathy and to the amount of free thyroxine (FT4). Conclusion: The MRE technique provides a new tool to gain new insights into pathophysiology of thyroid associated and other muscle diseases and their response to treatment.