Objective: The suitability of magnetic resonance imaging (MRI) for serial monitoring of bone pathology in the guinea pig stifle joint, an in vivo model of osteoarthritis, was investigated.
Methods: MR images were compared with histologic features and radiographs of 1-mm-thick sections to determine the MR correlates of the bone changes. Ten guinea pigs were then imaged on 7 occasions over the first year of life, enabling serial measurements of subchondral bone thickness, subchondral pseudocysts, and osteophytes.
Results: The signal intensity of trabecular bone in MR images accurately reflected the degree of osteopenia and trabecular thinning noted around the cruciate ligament insertions. The extent of subchondral sclerosis and the development of marginal osteophytes were also accurately represented. Serial observations revealed that MRI can detect highly significant progression of lytic bone lesions, subchondral sclerosis, and osteophyte size over periods of 6 weeks.
Conclusion: MRI is not only a reliable technique for the assessment of bone pathology but is also a useful tool for monitoring the progression of bone damage in osteoarthritis.