Cartilage shape-informed 3D gray level co-occurrence matrix analysis of DESS T2 maps

Motivation: To gain additional information about cartilage ultrastructure non-invasively from T2 maps. Goal(s): To assess the stability of 3D GLCM features calculated based on cartilage shape, compared to the conventional 13 volumetric directions, using 3D DESS T2 map. Approach: 5 volunteers underwent test-retest scan using 3D DESS sequence. From T2 maps, 20 GLCM features were calculated using 3 approaches: calculated in 13 volumetric directions and then averged; calculated along normal vectors of voxels; and along main axis projections to the tangent plane. Results: Cartilage shape oriented calculation resulted in higher repeatability based on ICC3 coefficient. Impact: This study demonstrates the high repeatability of cartilage shape informed 3D GLCM features. Since cartilage structure varies in directions perpendicular and parallel to the bone-cartilage interface, accurately assessing texture in these anatomically relevant orientations is clinically important.