Development of a Spin Tag Sequence with Spiral Acquisition for Elucidating Shear at the Deep Gastrocnemius Aponeurosis and Other Dynamics of the Musculoskeletal Elements of the Lower Leg.

Gajanan Nagarsekar¹, John Hodgson¹, David Shin¹, Shantanu Sinha¹

In order to visualize dynamics of the active and passive components of the musculoskeletal system at 100% maximum voluntary contractions, a rapid method using gated spin tagging with spiral acquisition was developed that allowed acquisition of high resolution images in 16~21 contractions. Movement of soleus and gastrocnemius during isometric and passive plantar-flexion was imaged in 6 subjects using a home-built computer controlled foot pedal device. Significant differences in displacement between the two muscles were observed. These surprising findings suggest minimal mechanical interactions between the soleus and gastrocnemius aponeuroses and significant functional disparity between adjacent regions of soleus and gastrocnemius muscles.