Computer‐controlled, MR‐compatible foot‐pedal device to study dynamics of the muscle tendon complex under isometric, concentric, and eccentric contractions

Abstract

Purpose To design a computer-controlled, MR compatible foot pedal device that allows in vivo mapping of changes in morphology and in strain of different musculoskeletal components of the lower leg under passive, isometric, concentric and eccentric contractions. Materials and Methods A programmable servo-motor in the control room pumped hydraulic fluid to rotate a foot-pedal inside the magnet. Towards validating the performance of the device, six subjects were imaged with gated velocity-encoded phase-contrast (VE-PC) imaging to investigate dynamics of muscle and aponeurotic structures. Results Artifact-free VE-PC imaging clearly delineated different muscle compartments by differences in distribution of mechanical strains. High repeatability of contraction cycles allowed establishing that fascicles lengthened 6.1% more during passive compared to eccentric contractions. Aponeurosis separation during passive (range between three locations: −2.6~1.3 mm) and active (range: −2.4 ~1.6 mm) contractions were similar but significantly different from concentric (range: −0.9~3.3 mm), with proximal and distal regions showing mostly negative values for the first two modes, but positive for the last. Conclusion The device was sufficiently robust and artifact-free to accurately assess, using VE-PC imaging, physiologically important structure and dynamics of the musculo-tendon complex.

Characterization of three dimensional volumetric strain distribution during passive tension of the human tibialis anterior using Cine Phase Contrast MRI

“…For example, a high-speed 3D radial cine phase contrast acquisition method has enabled acceleration factors of up to 11 with adequate SNR for angiography applications (Johnson et al, 2008). Additionally, muscle activation studies have been successfully performed previously involving multiple scans of several minute repeated muscle activations at 40% of maximal voluntary contraction (Sinha et al, 2012). …”

Method of quantifying 3D strain distribution in skeletal muscle using cine phase contrast MRI

“…This is important for avoiding artifacts due to non-identical repetitions [32]. The strong agreement between the strained mesh and the outline of the TA when the ankle was plantarflexed (0.6±0.2 mm RMS error) indicates good accuracy of the results by demonstrating that the trajectories of the most superficial nodes behaved as expected.…”

Error analysis of cine phase contrast MRI velocity measurements used for strain calculation

“…In this study’s sample calculations displacement accuracy was found to improve with systematic error correction but not strain accuracy, indicating that the systematic velocity error generated displacement error but not strain error. This was because the velocity distribution was uniform in this application and sampling error did not apply as it would in vivo (Hodgson et al, 2006; Sinha et al, 2012). The magnitude of this sampling error in vivo is difficult to predict, but should be considered in an error analysis.…”

“…Two-dimensional cine Phase Contrast (CPC) is an MRI measurement technique that has been used by several research groups to calculate the distribution of strain in a single plane in skeletal muscles (Finni et al, 2003; Kinugasa et al, 2008; Pappas et al, 2002; Sinha et al, 2012; Zhou and Novotny, 2007). The imaging sequence is used to acquire a temporal sampling of spatial velocity distributions in the muscle over a motion cycle.…”