4D Time-Resolved Strain Tensor Analysis Using Spectro-Dynamic MRI Reveals Muscle Activation Patterns

Motivation: In vivo biomechanical analysis can reveal novel information about the functioning of muscles. This information is preferably obtained dynamically, but this requires time-resolved reconstructions of deformations. Goal(s): To measure time-resolved 4D strain tensors using the Spectro-Dynamic MRI framework to study dynamic muscle activations in vivo. Approach: A pressure cuff compressed the muscles in the thigh, both with relaxed muscles and during isometric flexion of the knee. The experiment was repeated to investigate the repeatability. Results: Time-resolved 4D motion fields can be robustly estimated at 3 Hz. The strain values reveal activation of the biceps femoris during isometric flexion of the knee. Impact: Time-resolved 4D strain analysis using Spectro-Dynamic MRI enables the measurement of in vivo biomechanics in a dynamic setting. This creates an opportunity for new ways to investigate the functioning and performance of active muscles.