T2*mapping and subregion analysis of the tibialis posterior tendon using 3 Tesla magnetic resonance imaging

Objective: Early detection of tibialis posterior tendon changes and appropriate intervention is necessary to prevent disease progression to flat-foot deformity and foot/ankle dysfunction, and the need for operative treatment. Currently, differentiating between early-stage tibialis posterior tendon deficiency patients who will benefit from conservative vs more aggressive treatment is challenging. The objective of this work was to establish a quantitative MRI T2* mapping method and subregion baseline values in the tibialis posterior tendon in asymptomatic ankles for future clinical application in detecting tendon degeneration. Methods: 26 asymptomatic volunteers underwent T2* mapping. The tendon was divided axially into seven subregions. Summary statistics for T2* within each subregion were calculated and compared using Tukey post-hoc pairwise comparisons. Results: Results are reported for 24 subjects. The mean tibialis posterior tendon T2* was 7 +/- 1 ms. Subregion values ranged from 6 +/- 1 to 9 +/- 2 ms with significant between-region differences in T2*. Inter- and intrarater absolute agreement intraclass correlation coefficient (ICC) values were all "excellent" (0.75 < ICC=1.00) except for regions 5 through 7, which had "fair to good" interrater and/or and intrarater ICC values (0.4 < ICC=0.75). Conclusion: A tibialis posterior tendon T2* mapping protocol, subregion division method, and baseline T2* values for clinically relevant regions were established. Significant differences in T2* were observed along the tendon length. Advances in knowledge: This work demonstrates that regional variation exists and should be considered for future TT-based research on posterior tibias tendon degeneration and when using T2* mapping to evaluate for potential tibialis posterior tendon degeneration.