1Biomedical Engineering, University of Wisconsin, Madison, WI, United States; 2Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States; 3Medical Physics, University of Wisconsin, Madison, WI, United States; 4Radiology, University of Wisconsin, Madison, WI, United States
This study was performed to investigate the factors leading to changes in qMT measures of cartilage in controlled conditions including phantom experiments and an ex-vivo bovine cartilage degradation model. Bound pool fraction (f) and exchange rate (k) increased significantly with increasing concentration of collagen solution but changed only minimally with increasing concentration of proteoglycan solution. Thermal denaturation of collagen solution resulted in a decrease in f and k and increase in T2 relaxation time of bound protons (T2B). Trypsin degradation of bovine cartilage resulted in a decrease in k and increase in T2B but no change in f. Our results support strong association of f with collagen content. The observed trends and unique sensitivity of qMT measures to macromolecules, however, suggest that a multivariate analysis involving all qMT parameters may be the most specific method to analyze the complex changes which occur during cartilage degeneration.