T2 Mapping of Articular Cartilage of the Adult Knee Joint: Changes in the Relaxation Time and Thickness of Knee Cartilage with Age among Normal Adult Patients in 3 Tesla MRI

Background Degenerative joint disease, such as osteoarthritis, is characterized by the breakdown of cartilage in the joints, resulting in a decreased range of motion and stiffness. The T2 mapping approach is a very useful tool for detecting early osteoarthritis. The main goal of the study was to assess the variations in the relaxation time and articular cartilage thickness of knee cartilage across different age groups among healthy adults using the T2 mapping technique in 3 Tesla magnetic resonance imaging. Methods A total of 42 measurements were taken from each individual's knee cartilage and were confirmed to have no cartilage damage. The relaxation time was calculated from T2 maps using 21 circular regions of interest and the articular cartilage thickness was measured using 21 linear measurements from a self-created fusion image. The thickness was measured in the same regions where the relaxation time was measured. Overall, 2,142 measurements (1,071 circular regions of interest from T2 maps and 1,071 linear measurements from fusion images) were taken from 51 participants. Results The majority of the variables of T2 relaxation time show a positive linear correlation with age groups. As age increases, cartilage relaxation time increases, which may be connected to an increase in cartilage degeneration. However, half of the variables associated with knee cartilage thickness show a negative linear correlation with age group. As age increases, the thickness of the cartilage starts to decrease. T2 relaxation times of the middle lateral tibial condyle, middle superior patella, and central inferior patella differ significantly between healthy males and females ( p < 0.05). The cartilage thickness of the posterior lateral tibial condyle, middle medial patella, central superior patella, central middle patella, and lateral middle patella varied significantly between healthy males and females ( p < 0. 05). Conclusion Using an additional T2 articular cartilage mapping sequence to a routine sequence in the knee joint can reveal age-related changes in relaxation time and cartilage thickness in knee cartilage. The T2 mapping technique also can help detect early changes in osteoarthritis, track progression, and plan treatment.