Running-related musculoskeletal injury (RRMI) is a common occurrence among runners. Magnetic resonance imaging (MRI) plays a crucial role in diagnosing knee joint abnormalities and grading injuries affecting the cartilage and other structures of the knee joint. Ultrashort echo time (UTE) sequences, with echo times (TEs) approximately 10 to 1000 times shorter than conventional fast spin echo or gradient echo sequences, have been developed and utilized for imaging both short and long T2 tissues, as well as tissue components within the musculoskeletal system.

Quantitative UTE techniques, including UTE-T2*, UTE-T1rho, and UTE magnetization transfer (UTE-MT), have been introduced to evaluate compositional changes in both short and long T2 tissues. Among these techniques, several studies have demonstrated that the UTE-MT technique exhibits significantly lower sensitivity to the magic angle effect, making it a promising tool for assessing collagen-rich tissues, such as cartilage.

This prospective longitudinal study was approved by the Institutional Ethics Review Board, and written informed consent was obtained from all participants. Twenty-seven amateur long-distance runners underwent bilateral tibiotalar joint MRI examinations at three time points: pre-run, 48 hours post-run, and 4 weeks post-run. UTE-MT sequences were utilized to quantify the magnetization transfer ratio (UTE-MTR) across cartilage subregions. For analysis, one medial and one lateral UTE-MT slice were selected per joint, with each slice subdivided into six regions of interest (ROIs): anterior, middle, and posterior tibial/talar cartilage (Fig. A). Longitudinal UTE-MTR changes were assessed across the three time points, and regional variations were statistically analyzed. Inter-rater reliability and sequence reproducibility were evaluated using a two-way mixed intraclass correlation coefficient (ICC).