Quantitative in-vivo analysis of biomechanical properties reveals tissue stiffness changes during contraction of the thigh muscles.

Motivation: Quantitative in-vivo analysis of muscle stiffness provides insight in the functioning of the musculoskeletal system, but no robust reconstruction algorithm is available that uses displacement fields on a physiological time-scale. Goal(s): Development of a robust reconstruction approach for quantitative biomechanical properties without using boundary information. Approach: An inflatable pressure cuff is used to induce deformations in thigh muscles during an MRI scan. Time-resolved displacement fields are recontructed and used to distill quantitative stiffness information for relaxed and contracted muscles. Results: Nummerical tests and an in-vivo repeatability study corroborate the validity of the proposed approach. An increase in stiffness is observed during muscle contraction. Impact: Access to in-vivo stiffness parameters could give insight in muscle functionality. We developed an algorithm that is able to recontruct quantitative biomechanical properties from information acquired during a simple dynamic loading experiment without using boundary information.