Proteoglycan and collagen sensitive MRI evaluation of normal and degenerated articular cartilage

Quantitative magnetic: resonance imaging (MRI) techniques have earlier been developed to characterize the structure and composition of articular cartilage. Particularly, Gd-DTPA(2-)-enhanced T-1 imaging is sensitive to cartilage proteoglyean content, while T relaxation time mapping is indicative of the integrity and arrangement of the collagen network. However, the ability of these techniques to detect: early osteoarthrotic changes in cartilage has not been demonstrated. In this study, normal and spontaneously degenerated bovine patellar cartilage samples (n = 32) were investigated in vitro using the aforementioned techniques. For reference, mechanical, histological and biochemical properties of the adjacent tissue were determined, and a grading system, the cartilage quality index (CQI), was used to score the structural and functional integrity of each sample. As cartilage degeneration progressed, a statistically significant increase in the superficial T (r = 0.494, p < 0.05) and a decrease in superficial and bulk T, in the presence of Gd-DTPA(2-) (r = -0.681 and -0.688 (p < 0.05), respectively) were observed. Gd-DTPA(2-)-enhanced T-1 imaging served as the best predictor of tissue integrity and accounted for about 50% of the variation in CQI. The present results reveal that changes in the quantitative MRI parameters studied are indicative of structural and compositional alterations as well as the mechanical impairment of spontaneously degenerated articular cartilage. (C) 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.