In vivo ARFI imaging of the mechanical properties of muscle in a dog model of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder that is caused by a mutation in the gene for dystrophin leading to a loss of the dystrophin protein from the muscle cell (myofiber) membrane. We have investigated the use of Acoustic Radiation Focus Impulse (ARFI) imaging in a dog model for DMD. Imaging was performed in vivo on the right rectus femoris and cranial sartorius muscles of three pairs of normal/DMD littermates. Three ARFI excitation methods were employed: (1) a single ARFI excitation impulse, (2) a double excitation impulse, and (3) Shear Wave Elasticity Imaging (SWEI). ARFI imaging was completed in planes transverse and parallel to muscle fibers. Both rectus femoris and cranial sartorius muscles were observed to be less displaceable (single-excitation) in DMD dogs than in the controls. DMD muscles also displayed a smaller difference in peaks (double-excitation). These results suggest that the rectus femoris and cranial sartorius muscles stiffen with DMD and demonstrate the feasibility of noninvasive ARFI for monitoring muscular chances in DMD.