T 2 relaxation time measurements are limited in monitoring progression, once advanced cartilage defects at the knee occur: Longitudinal data from the osteoarthritis initiative

Purpose To study the natural evolution of cartilage T 2 relaxation times in knees with various extents of morphological cartilage abnormalities, assessed with 3 Tesla MRI from the Osteoarthritis Initiative. Materials and Methods Right knee MRIs of 245, 45‐ to 60‐year‐old individuals without radiographic osteoarthritis (OA) were included. Cartilage was segmented and T 2 maps were generated in five compartments (patella, medial and lateral femoral condyle, medial, and lateral tibia) at baseline and 2‐year follow‐up. We examined the association of T 2 values and 2‐year change of T 2 values with various Whole‐Organ MR Imaging Scores (WORMS). Statistical analysis was performed with analysis of variance and Students t‐tests. Results Higher baseline T 2 was associated with more severe cartilage defects at baseline and subsequent cartilage loss ( P  < 0.001). However, longitudinal T 2 change was inversely associated with both baseline ( P  = 0.038) and follow‐up ( P  = 0.002) severity of cartilage defects. Knees that developed new cartilage defects had smaller increases in T 2 than subjects without defects ( P  = 0.045). Individuals with higher baseline T 2 showed smaller T 2 increases over time ( P  < 0.001). Conclusion An inverse correlation of longitudinal T 2 changes versus baseline T 2 values and morphological cartilage abnormalities suggests that once morphological cartilage defects occur, T 2 values may be limited for evaluating further cartilage degradation. J. Magn. Reson. Imaging 2013;38:1415–1424. © 2013 Wiley Periodicals, Inc.