Purpose: To assess reliability and clinical utility of evaluating stress-related metaphyseal water distribution using a semi-quantitative Dixon MRI-based method for early diagnosis of physeal stress injuries in adolescent gymnasts. Methods: Twenty-four gymnasts with clinically suspected overuse injury of the distal radial physis, 18 asymptomatic gymnasts, and 24 non-gymnast controls aged 12 ± 1.5 years prospectively underwent hand radiographs and 3T MRI of the wrist including coronal T1-weighted and T2-weighted Dixon sequences. Two raters measured metaphyseal water signal fraction in 13 radial and ulnar regions of interest (ROI). Inter- and intrarater reliability, interslice (between 3 middle radial slices), and inter-ROI (between 3 ROIs on same level) reliability were assessed using intraclass correlation coefficients (ICC). Water signal fractions and their within-person ratios in distal versus most proximal ROIs were compared between groups using one-way analysis of variance. Results: Inter- and intrarater ICCs were 0.79–0.99 and 0.94–1.0 for T1-weighted, and 0.88–1.0 and 0.88–1.0 for T2-weighted Dixon. Interslice and inter-ROI ICCs were 0.55–0.94 and 0.95–0.97 for T1-weighted, and 0.70–0.96 and 0.96–0.97 for T2-weighted Dixon. Metaphyseal water signal fraction in symptomatic gymnasts was higher in six distal ROIs compared with asymptomatic gymnasts and in nine ROIs compared with non-gymnasts (p < 0.05). Metaphyseal water score (ratio of distal versus most proximal ROIs) was 1.61 in symptomatic gymnasts and 1.35 in asymptomatic gymnasts on T2-weighted Dixon (p < 0.05). Conclusion: Semi-quantitative Dixon MRI-based water signal fraction assessment has good to excellent reproducibility and shows increased metaphyseal water scores in symptomatic gymnasts compared with asymptomatic gymnastic peers. Key Points: • The proposed Dixon MRI-based semi-quantitative method for assessment of metaphyseal bone marrow water content is reliable, with off-the-shelf availability and short scan times. • The metaphyseal water score allows comparisons between gymnasts using a within-person reference area for unaffected metaphyseal bone. • As metaphyseal water score was increased in symptomatic gymnasts compared with asymptomatic gymnasts, this semi-quantitative method can potentially be used as an indicator of bone marrow edema in the early diagnosis of gymnastic physeal stress injury.
Kox, L. S., Kraan, R. B. J., Mazzoli, V., Mens, M. A., Kerkhoffs, G. M. J. J., Nederveen, A. J., & Maas, M. (2019). It’s a thin line: development and validation of Dixon MRI-based semi-quantitative assessment of stress-related bone marrow edema in the wrists of young gymnasts and non-gymnasts. European Radiology. https://doi.org/10.1007/s00330-019-06446-8