Normalized STEAM-based diffusion tensor imaging provides a robust assessment of muscle tears in football players: preliminary results of a new approach to evaluate muscle injuries

OBJECTIVES: To assess acute muscle tears in professional football players by diffusion tensor imaging (DTI) and evaluate the impact of normalization of data. METHODS: Eight football players with acute lower limb muscle tears were examined. DTI metrics of the injured muscle and corresponding healthy contralateral muscle and of ROIs drawn in muscle tears (ROI(tear)) in the corresponding healthy contralateral muscle (ROI(hc_t)) in a healthy area ipsilateral to the injury (ROI(hi)) and in a corresponding contralateral area (ROI(hc_i)) were compared. The same comparison was performed for ratios of the injured (ROI(tear)/ROI(hi)) and contralateral sides (ROI(hc_t)/ROI(hc_i)). ANOVA, Bonferroni-corrected post-hoc and Student’s t-tests were used. RESULTS: Analyses of the entire muscle did not show any differences (p>0.05 each) except for axial diffusivity (AD; p=0.048). ROI(tear) showed higher mean diffusivity (MD) and AD than ROI(hc_t) (p<0.05). Fractional anisotropy (FA) was lower in ROI(tear) than in ROI(hi) and ROI(hc_t) (p<0.05). Radial diffusivity (RD) was higher in ROI(tear) than in any other ROI (p<0.05). Ratios revealed higher MD and RD and lower FA and reduced number and length of fibre tracts on the injured side (p<0.05 each). CONCLUSIONS: DTI allowed a robust assessment of muscle tears in athletes especially after normalization to healthy muscle tissue. KEY POINTS: • STEAM-based DTI allows the investigation of muscle tears affecting professional football players. • Fractional anisotropy and mean diffusivity differ between injured and healthy muscle areas. • Only normalized data show differences of fibre tracking metrics in muscle tears. • The normalization of DTI-metrics enables a more robust characterization of muscle tears.