Association between radiography-based subchondral bone structure and MRI-based cartilage composition in...

Our aim was to investigate the relation between radiograph-based subchondral bone structure and cartilage composition assessed with delayed gadolinium enhanced magnetic resonance imaging of cartilage (dGEMRIC) and T₂ relaxation time.

Ninety-three postmenopausal women (Kellgren-Lawrence grade 0: n = 13, 1: n = 26, 2: n = 54) were included. Radiograph-based bone structure was assessed using entropy of the Laplacian-based image (E_Lap) and local binary patterns (E_LBP), homogeneity indices of the local angles (HI_Angles,mean, HI_Angles,Perp, HI_Angles,Paral), and horizontal (FD_Hor) and vertical fractal dimensions (FD_Ver). Mean dGEMRIC index and T₂ relaxation time of tibial cartilage were calculated to estimate cartilage composition.

HI_Angles,mean (r_s = -0.22) and HI_Angles,Paral (r_s = -0.24) in medial subchondral bone were related (P < 0.05) to dGEMRIC index of the medial tibial cartilage. E_Lap (r_s = -0.23), FD_Hor,0.34 mm (r = 0.21) and FD_Ver,0.68 mm (r = 0.24) in medial subchondral bone were related (P < 0.05) to T₂ relaxation time values of the medial tibial cartilage. FD_Hor at different scales in lateral subchondral bone were related (P < 0.01) to dGEMRIC index (r = 0.29-0.41) and T₂ values of lateral tibial cartilage (r = -0.28 to -0.36). FD_Ver at larger scales were related (P < 0.05) to dGEMRIC index (r = 0.24-0.25) and T₂ values of lateral tibial cartilage (r = -0.21). HI_Angles,Paral (r = -0.25) and FD_Ver,0.68 mm (r_s = 0.22) in the lateral tibial trabecular bone were related (P < 0.05) to dGEMRIC index of the lateral tibial cartilage.

Our results support the presumption that several tissues are affected in the early osteoarthritis (OA). Furthermore, they indicate that the detailed analysis of radiographs may serve as a complementary imaging tool for OA studies.