Date of Award


Document Type


Degree Name

Master of Science (MS)


Biomedical Engineering

First Advisor

Mathew J. Failla


Purpose: Quantitative magnetic resonance imaging (qMRI) metrics, including T1ρ and T2*, exhibit considerable promise as image-based biomarkers to monitor the progression of osteoarthritis and post traumatic osteoarthritis. The potential for tracking disease progression utilizing these metrics may be further enhanced with the joint under loaded conditions, as an abnormal response to loading may contribute to cartilage degeneration. Reliability and repeatability studies for T1ρ and T2* measurements have yielded variable results, compared surgical to non- surgical knees, employed diverse sample regions of interest, and acquired images under traditional non-weight bearing knee conditions. The purposes of this study are to quantify side-to-side and visit-to-visit repeatability of T1ρ and T2* in healthy subjects in both unloaded and loaded cartilage, and to evaluate how ROI selection affects the variability of relaxation times.Materials and Methods: Ten healthy participants (6 female, 4 male) underwent bilateral qMRI over two visits (7±3 days apart) on the same Philips 3T MR system. After scanning without load, each knee was imaged with a 40% body-weight external load applied to the knee using a custom-built MRI-compatible loading device. Interclass correlation coefficients (ICC) and ANOVA with statistical significance of p < .05 were used to analyze left-to-right and visit-to-visit differences. Results: Across all ROIs, T1ρ ICCs ranged from 0.13-0.77, while T2* ICCs ranged from 0.22-0.82. Across all ROIs, left-to-right mean differences were 2.6 ms for T1ρ and 1.9 ms for T2* and visit-to-visit, mean differences were .003 ms for T1ρ and -0.2 ms for T2*. Conclusion: Quantitative MRI has fair repeatability, with tibial cartilage generally better than femoral cartilage, but may be affected by ROI selection and subject to a limb sidedness bias that needs further investigation.



Number of Pages

38 p.