Multi-frame biomechanical and relaxometry analysis during in vivo loading of the human knee by spiral dualMRI and compressed sensing

Abstract

Purpose: Knee cartilage experiences repetitive loading during physical activities, which is altered during the pathogenesis of diseases like osteoarthritis. Analyzing the biomechanics during motion provides a clear understanding of the dynamics of cartilage deformation, and may establish essential imaging biomarkers of early-stage disease. However, in vivo biomechanical analysis of cartilage during rapid motion is not well established. Methods: We used spiral DENSE MRI on in vivo human tibiofemoral cartilage during cyclic varus loading (0.5 Hz) and employed compressed sensing on the k-space data. The applied compressive load was set for each participant at 0.5x body weight on the medial condyle. Relaxometry methods were measured on the cartilage before (T1ρ, T2) and after (T1ρ) varus load. Results: Displacement and strain maps showed a gradual shift of displacement and strain in time. Compressive strain was observed in the medial condyle cartilage and shear strain was roughly half of the compressive strain. Male participants had more displacement in the loading direction compared to females, and T1ρ values did not change after cyclic varus load. Compressed sensing reduced the scanning time up to 25-40% when comparing the displacement maps and substantially lowered the noise levels. Conclusion: These results demonstrated the ease of which spiral DENSE MRI could be applied to clinical studies due to the shortened imaging time, while quantifying realistic cartilage deformations that occur through daily activities, and that could serve as biomarkers of early osteoarthritis.

Updates on Compositional MRI Mapping of the Cartilage: Emerging Techniques and Applications

“…11, and intervertebral discs 100 . Displacement encoding with stimulated echoes (DENSE) MRI was used on human cartilage during cyclic varus loading to assess displacement and strain 101 . Also in the study by, 101 T 1ρ maps were acquired before and after varus loading to investigate changes with this kind of loading.…”

“…100 Displacement encoding with stimulated echoes (DENSE) MRI was used on human cartilage during cyclic varus loading to assess displacement and strain. 101 Also in the study by, 101 T 1ρ maps were acquired before and after varus loading to investigate changes with this kind of loading. This emerging topic shows the utility of assessing biomechanical function using noninvasive MRI methods under mechanical loading.…”

Multi‐frame biomechanical and relaxometry analysis during in vivo loading of the human knee by spiral dualMRI and compressed sensing

“…We used l2 regularization (λ = 0.01) and all processes underwent five iterations. 32 This process was applied to each individual average (1-8) and frame . Subsequently, image averaging of the CS reconstructed images was performed on both the magnitude and phase images.…”

“…Therefore, DENSE MRI can greatly benefit from CS by reducing the scanning time, which is more tolerable for participants and induces less motion artifacts for maintaining a static posture in the reduced scanning time. 32 In this paper, we acquired high frame rate (25 frames/s) displacement and strain maps on human in vivo cartilage using spiral DENSE MRI during varus load. The loading frequency was 0.5 Hz, comparable to walking cadence; therefore, our results would demonstrate cartilage deformation occurring in daily activities.…”

MRI-derived Articular Cartilage Strains Predict Patient-Reported Outcomes Six Months Post Anterior Cruciate Ligament Reconstruction

“…Recently, as a mechanical complement to qMRI, we pioneered displacement under applied loading MRI (dualMRI) to measure cartilage mechanical properties and quantify joint health 6,31,32,55 . dualMRI quantifies pixel-level full-field displacement and strain maps (i.e., "elastography" maps 4,29 ) of cartilage while under a cyclical physiological load within the imaging scanner, mimicking a walking cadence.…”