Regional variation of ankle and hindfoot cartilage T2 mapping values at 3 T: A feasibility study

Objective: To develop a method for T2 mapping of the entire tibiotalar/hindfoot articular surfaces and to examine regional T2 variation in asymptomatic volunteers, establishing necessary methods for future T2 mapping work in patients with ankle/hindfoot injury. Materials and methods: Twenty-six asymptomatic volunteers (11 female/13 male, aged 23-64 years in final analysis) underwent sagittal T2 mapping. Tibiotalar and hindfoot cartilage surfaces were segmented by two raters. The tibiotalar joint cartilage was divided into subregions to assess T2 variation across the joint. The articular surface and subregion mean T2 values were compared using Tukey post hoc pairwise comparisons to test for statistical significance. Results and conclusion: Mean ankle/hindfoot cartilage T2 ranged from 37 +/- 3 to 47 +/- 7 ms. Tibial plafond mean T2 was significantly different from the middle and posterior subtalar cartilage T2 (both articular surface comparisons resulted in P <.05). Talar dome mean T2 was significantly different from the posterior calcanealside and talar-side subtalar cartilage, and middle calcaneal-side subtalar cartilage (P <.05 for all comparisons). Tibial plafond middle versus lateral, anterior versus middle, middle versus posterior, and anterior versus posterior subregion T2 values were significantly different (P <.05 for all comparisons). Talar dome medial versus middle, middle versus lateral, anterior versus middle, and middle versus posterior subregion T2 values were significantly different (P <.05 for all comparisons). Ankle/hindfoot joint cartilage T2 mapping and segmentation was found to be feasible for all cartilage surfaces except the anterior subtalar joint facet. Mean T2 differed significantly between ankle/hindfoot joint and subregion cartilage in asymptomatic volunteers.