Shantanu Sinha PhD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: To correlate the structure of the human multipennate soleus muscle in vivo as elucidated by high resolution MRI and 3D volume rendering, with the heterogeneous spatial distribution of functionality, determined in terms of peak shortening velocity during isometric contraction using velocity encoded, phase contrast MRI. Methods and Materials: With both legs of the subject inserted into the head coil of a GE LX 1.5T scanner, with the right immobilized within a half cast, high resolution axial images of the entire lower leg were acquired for 3D reconstruction in a Vitrea workstation for structural information (N=10). The subject was trained to exert isometric contractions timed to a computer generated audio cue. The output of an optical force transducer, imbedded in the sole of the cast, was used to measure force exerted and to gate the scan. It also provided a feedback to the subject via a LED bar-graph, both for timing and for consistency of force exerted as a fraction of MVC, and for subsequent force-strain analysis. For N=2 subjects, 5 to 8 saggital, and 2~4 axial, 4 views/segment, velocity encoded (VENC=10cm/s S/I), PC images were acquired with TE/TR/Flip angle of 5.3/11.3/30o, 2 Avg, 22 cm FOV, 5 cm Sl.Thk, 20 phases/R-R. The PC images were analyzed and mapped onto the anatomical images using an in-house built software. Results: The 3D volume rendering of the soleus muscle revealed a complex internal structure, with the curved aponeurosis arising distally from the Achilles tendon covering the posterior aspect of the muscle and extending into its superior regions. A clear anterior protrusion from this aponeurosis, with its thickness and extent varying amongst subjects, extended along the longitudinal axis of the soleus into the superior region of the muscle. Extensive distribution of intramuscular connective tissue forms a somewhat diffuse structure. The distribution of velocity of tissues in the saggital and axial planes was clearly delineated into different domains, defined by different muscle fascicle orientation during a contraction. Those in proximity to the connective tissues associated with the insertion had in general about 1~2 cm/s higher velocity than tissues in proximity of the origin. Conclusion: The detailed 3D structure of the anatomy as revealed in these studies, particularly in terms of possible fiber orientations, explained quite well the distribution of peak velocities in different parts of the triceps surae complex, providing new insights into the structure-function relationships of complex multi-pennate muscles.       Questions about this event email: ssinha@mednet.ucla.edu

Sinha PhD, S, Correlating Function of the Human Soleus Muscle as Characterized by Peak Velocity during Isometric Contraction, with Its Structure.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3107349.html