Ultrashort Echo Time Magnetization Transfer Imaging for Dynamic Monitoring of Ankle Cartilage After Long-Distance Running

Background: Ankle cartilage is prone to degeneration due to overuse. Developing a non-invasive MRI technique to detect early running-induced lesions enables timely intervention. Purpose: To evaluate the value of the ultrashort echo time magnetization transfer (UTE-MT) sequence in monitoring tibiotalar cartilage changes in amateur marathon runners before and after a marathon. Study Type: Prospective. Subjects: Thirty amateur marathon runners (25 males, 5 females; range: 24–50 years). Sequence: 3D UTE-MT (gradient-echo), 3D UTE-T2* (gradient-echo). Assessment: MRI scans at three time points: 1 week pre-marathon, 2 days post-marathon, and 4 weeks post-marathon. Medial and lateral tibiotalar cartilage was subdivided into 12 subregions, consisting of anterior, middle, and posterior segments for the tibial and talus parts on each side. The UTE-MTR and UTE-T2* values were measured per subregion at each time point. Statistical Tests: Repeated measures one-way ANOVA and the Tukey test. p < 0.05 was considered statistically significant. Results: Most cartilage subregions showed decreased UTE-MTR values 2 days post-marathon and increased after 4 weeks. Significant differences in UTE-MTR over time were observed in 9 subregions, including the medial and lateral anterior, middle, and posterior tibial cartilage (MTiA, MTiM, MTiP, LTiA, LTiM, LTiP), the medial and lateral posterior talus regions (MTaP, LTaP), and the medial middle talus cartilage (MTaM). Post hoc tests revealed significant UTE-MTR decreases 2 days post-marathon in all 9 regions (Rate: MTiA: −3.9%; MTiM: −2.8%; MTiP: −3.0%; MTaP: −4.5%; MTaM: −4.2%; LTiA: −3.5%; LTiM: −4.7%; LTiP: −5.8%; LTaP: −6.8%), with significant increases in MTiA (3.7%) and MTaM (4.4%) at 4 weeks. UTE-T2* values rose in most cartilage regions at 2 days post-marathon and continued increasing at 4 weeks. Only MTiP, LTiM, and LTaM showed significant changes. Data Conclusion: This study demonstrates that the UTE-MT sequence enables the quantitative assessment of dynamic changes in tibiotalar joint cartilage after a marathon. Level of Evidence: 2. Technical Efficacy: Stage 1.