Objective: To characterize delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) features of healthy hyaline cartilage of the distal interphalangeal joint (DIPJ) of horses, to determine whether dGEMRIC can be used to differentiate various stages of naturally occurring osteoarthritis of the DIPJ, and to correlate relaxation times determined by dGEMRIC with the glycosaminoglycan concentration, water content, and macroscopic and histologic findings of hyaline cartilage of DIPJs with and without osteoarthritis.
Sample: 1 cadaveric forelimb DIPJ from each of 12 adult warmblood horses.
Procedures: T1-weighted cartilage relaxation times were obtained for predetermined sites of the DIPJ before (T1preGd) and after (T1postGd) intra-articular gadolinium administration. Corresponding cartilage sites underwent macroscopic, histologic, and immunohistochemical evaluation, and cartilage glycosaminoglycan concentration and water content were determined. Median T1preGd and T1postGd were correlated with macroscopic, histologic, and biochemical data. Mixed generalized linear models were created to evaluate the effects of cartilage site, articular surface, and macroscopic and histologic scores on relaxation times.
Results: 122 cartilage specimens were analyzed. Median T1postGd was lower than the median T1preGd for normal and diseased cartilage. Both T1preGd and T1postGd were correlated with macroscopic and histologic scores, whereby T1preGd increased and T1postGd decreased as osteoarthritis progressed. There was topographic variation of T1preGd and T1postGd within the DIPJ. Cartilage glycosaminoglycan concentration and water content were significantly correlated with T1preGd and macroscopic and histologic scores but were not correlated with T1postGd.
Conclusions and Clinical relevance: Results indicated that dGEMRIC relaxation times varied for DIPJs with various degrees of osteoarthritis. These findings may help facilitate early detection of osteoarthritis.