Purpose or Case Report: To evaluate the T2 map relaxation times in healthy male children and adolescent ankle cartilage under altered magnetic resonance image (MRI) protocols and to document trends in these T2 relaxation times with varying ages and body mass index (BMI).
Methods & Materials: This cross sectional study recruited 11 healthy male children and adolescents (median age of 14 years; range 8-17 years), who each underwent 3.0 Tesla T2 map MRI examinations of ankle (tibia-talus) using three protocols. Protocol 1 – a single echo spin echo constant TR/TE (TE = 13, 19, 28 ms; TR = 513, 519, 528 ms). Protocol 2 – a multi-echo spin echo (TE = 9.6, 19.2, 28.8 ms; TR = 1000 ms). Protocol 3 (high spatial resolution) – a multi-echo spin echo (TE = 11.1, 22.2, 33.3 ms; TR = 1690 ms). Images were analyzed at sagittal lateral and medial MRI slices using a house-made MATLAB software. A P value less than 0.05 was considered statistically significant.
Results: We found statistically significant negative associations between age and T2 relaxation times of ankle cartilage, ranging from -0.91 (P < 0.001) to -0.66 (P = 0.03) for all image protocols. Furthermore, statistically significant negative trends of T2 relaxation times for ankle cartilage were found with increasing age, ranging from -2.08 ms/year (P = 0.006) to -0.80 ms/year (P < 0.01) for all image protocols. Similarly, mean T2 relaxation times were found upon using a constant TR/TE to other image protocols, thus enforcing the generalizability of the protocol. In contrast, weak associations were found between BMI and ankle cartilage T2 relaxation times.
Conclusions: Age plays an important role in understanding cartilage T2 relaxation times. Additionally a TR/TE protocol can be used to help optimize scanning time for children and adolescents.