T2 Relaxation Time Measurements Are Limited in Monitoring Progression, Once Advanced Cartilage Defects at the Knee Occur: Longitudinal Data From the Osteoarthritis Initiative

PurposeTo 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 MethodsRight 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. ResultsHigher 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). ConclusionAn 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.