Evaluation of radial distribution of cartilage degeneration and necessity of pre-contrast measurements using radial dGEMRIC in adults with acetabular dysplasia

Background: The purpose of the present study was to investigate the radial distribution patterns of cartilage degeneration in dysplastic hips at different stages of secondary osteoarthritis (OA) by using radial delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), and to assess whether pre-contrast measurements are necessary. Methods: Thirty-five hips in 21 subjects (mean age +/- SD, 27.6 +/- 10.8 years) with acetabular dysplasia (lateral CE angle <25 degrees) were studied. Severity of OA was assessed on radiographs using Tonnis grading. Pre-(T1(pre)) and post-contrast T1 (T1(Gd)) values were measured at 7 sub-regions on radial reformatted slices acquired from a 3-dimensional (3D)T1 mapping sequence using a 1.5 T MR scanner. Values of radial T1(pre), T1(Gd) and Delta R1 (1/T1(Gd) - 1/T1(pre)) of subgroups with different severity of OA were compared to those of the subgroup without OA using nonparametric tests, and bivariate linear Pearson correlations between radial T1(Gd) and Delta R1 were analyzed for each subgroup. Results: Compared to the subgroup without OA, the subgroup with mild OA was observed with a significant decrease in T1(Gd) in the anterosuperior to superior sub-regions (mean, 476 similar to 507 ms, p = 0.026 similar to 0.042) and a significant increase in Delta R1 in the anterosuperior to superoposterior and posterior sub-regions (mean, 0.93 similar to 1.37 s(-1), p = 0.012 similar to 0.042). The subgroup with moderate to severe OA was observed with a significant overall decrease in T1(Gd) (mean, 404 similar to 452 ms, p = 0.001 similar to 0.020) and an increase in Delta R1 (mean, 1.17 similar to 1.69 s(-1), p = 0.001 similar to 0.020). High correlations were observed between radial T1(Gd) and Delta R1 for all subgroups (r = -0.869 similar to -0.944, p < 0.001). Conclusions: Radial dGEMRIC without pre-contrast measurements is useful for evaluating different patterns of cartilage degeneration in the entire hip joint of patients with hip dysplasia, particularly for those in early stages of secondary OA.