Changes in calf muscle elasticity in hypogonadal males before and after testosterone substitution as monitored by magnetic resonance elastography.

PURPOSE We sought to determine whether differences in muscle elasticity between healthy age-related controls and patients with hypogonadism could be measured by a new, non-invasive method termed magnetic resonance elastography (MRE). MATERIALS AND METHODS Twelve hypogonadal (21-68 years) and twenty-seven healthy age-related men (20-76 years) were examined. In the hypogonadism group, serum testosterone levels were compared and MRE was conducted prior to and after 6 months of therapy in 6 of the 12 patients. MRE was performed by mechanically exciting the soleus muscle that was used because of its uniformly distributed muscle fibers, size, and accessibility, with a custom designed piezoelectric-actuator using a modified phase-contrast sequence. For mechanical excitation the actuator lever was placed on the anterior surface of the calf. The subjects had to maintain a force of 0-20% of their maximum voluntary contraction against a home-built footplate that was mounted on the MR table. All images were phase unwrapped and reconstructed into shear modulus elastograms using the local frequency estimation technique. RESULTS Testosterone levels were significantly higher after 6 months of treatment. A statistical difference in the shear modulus was observed prior to and after 6 months of testosterone therapy and was nearly the same as in the healthy age-related control group. CONCLUSION MRE seems to be a promising technique for the evaluation of therapeutic effects in patients with hypogonadism and possibly in other diseases with muscular effects.