Efficacy of Apparent Diffusion Coefficient Sampling in Muscle Tears and Intersex Differences in Professional Football Players: A Cohort Study

Background: Magnetic resonance imaging (MRI) is the gold standard for monitoring the evolution of muscle injuries in athletes, although no established quantitative measure of recovery currently exists. Hypothesis: Apparent diffusion coefficient (ADC) values may provide a quantitative measure of muscle healing, and sex-related differences may exist in the evolution of muscle injuries. Study Design: Single-center retrospective observational cohort study. Level of Evidence: Level 2a. Methods: Twenty-six professional football (soccer) players (13 male ,13 female) undergoing MRI for muscle injury were retrospectively selected between October 2020 and June 2024. All athletes underwent MRI at baseline (T0) and at 2-week follow-up, including diffusion-weighted imaging (DWI) acquisitions with b values of 0-100-800 s/mm ² . Two musculoskeletal radiologists measured ADC values within the index lesions at each examination. Changes in ADC between the two time points (ΔADC) were assessed using a paired-samples t test, while sex-related differences were evaluated using the Mann–Whitney U test. Results: The overall mean ADC value at the lesion site decreased from 2.06 ± 0.35 mm 2 /s at T0 to 1.61 ± 0.30 mm 2 /s at follow-up corresponding to a mean ΔADC of 0.44 ± 0.20 and a 21.84% reduction. The difference between T0 and follow-up was statistically significant ( t = 8.12; P < 0.001). Mean ΔADC values were 0.32 ± 0.20 mm ² /s in male players and 0.56 ± 0.25 mm ² /s in female players, respectively, with a statistically significant difference between sexes (z = −2.95; P = 0.003). When only hamstring injuries were considered, female players showed a significantly greater decrease in ADC over time than male players (Mann–Whitney U test; exact P = 0.02), with mean ΔADC values of 0.56 ± 0.30 and 0.26 ± 0.08 mm ² /s, respectively. Conclusion: Muscle injury is associated with an acute increase in ADC values followed by a progressive decrease during healing. ADC may therefore represent a quantitative imaging biomarker for monitoring muscle recovery. Clinical Relevance: ADC measurement within muscle tears may provide a quantitative assessment of healing status and support individualized rehabilitation strategies in athletes. Sex-related differences may exist in injury pathophysiology and recovery patterns relevant to safe return to play.