Osteoarthritis (OA) is the most prevalent chronic disease in the elderly, and it is generally diagnosed at an advanced state when treatment is difficult if not impossible. The early form of OA is characterized by an elevated water content in the cartilage tissue. The purpose of this study was to verify in vivo if changes in the water content of patellar cartilage typically occurring in early OA can be detected using T(2) mapping MRI methods.
Twenty healthy volunteers performed 60 knee bends in order to compress their patellar cartilage thereby reducing its water content. MR images of the patellar cartilage were acquired immediately following exercise and after 45 min of rest. Patellar cartilage thickness and T(2) maps were determined and their difference between the time points evaluated.
Cartilage thickness increased by 5.4+/-1.5% from 2.94+/-0.15 mm to 3.10+/-0.15 mm (P< 0.001) following 45 min of rest, while T(2) increased by 2.6+/-1.0% from 23.1+/-0.5 ms to 23.7+/-0.6 ms (P< 0.05).
Small, physiologic changes in the water content of patellar cartilage and the concomitant change in proteoglycan and collagen density following exercise can be detected using MRI. The proposed T(2)-mapping method, together with other non-invasive MR cartilage imaging techniques, could aid in the early diagnosis of OA.