SPECT Imaging of Muscle Injury with [99mTc]MDP in a Mouse Model of Muscular Dystrophy

Abstract

Purpose: Tc-99m methylene diphosphonate ([99mTc]MDP) is an in vivo bone imaging agent that also accumulates in injured skeletal muscle cells. The objective of this study was to investigate if [99mTc]MDP could be used to detect muscle injury in the mdx mouse model of Duchenne muscular dystrophy (DMD). Procedures: Static whole-body single-photon emission computed tomography/computed tomography (CT) scans were acquired at 2 h post-injection of [99mTc]MDP in two cohorts of animals at different sites: one cohort of mice at 6, 15, and 19 weeks of age, and a separate cohort at 16 weeks. The second cohort was also imaged with high-resolution CT at 8 weeks. Results: mdx mice had higher [99mTc]MDP uptake and significantly higher [99mTc]MDP concentrations in muscle than controls. Conclusions: Higher uptake of [99mTc]MDP in muscle of mdx mice agrees with histological reports of muscle calcification in mdx mice, and suggests the potential translational use of [99mTc]MDP imaging for tracking DMD progression and therapeutic response.