Osteochondral Abnormalities on Three-Dimensional Ultrashort Echo Time MRI Scans Are Associated with Knee Cartilage Degradation

Background The calcified cartilage layer and subchondral bone plate (SBP) contribute to osteoarthritis development. Three-dimensional (3D) ultrashort echo-time (UTE) MRI can help to evaluate calcified cartilage and SBP in various stages of cartilage degradation. Purpose To compare calcified cartilage and SBP abnormalities using 3D UTE MRI with cartilage degradation and osteochondral junction (OCJ) abnormalities observed at proton-density fast spin-echo with fat suppression (PDFS) MRI. Materials and Methods Between April 2018 and March 2019, 143 participants were prospectively enrolled in this study and underwent routine knee MRI with an additional sagittal 3D UTE MRI examination for chronic knee pain. The MRI scans were retrospectively analyzed by two musculoskeletal radiologists independently and at consensus. Cartilage degradation grades and OCJ abnormalities were evaluated at PDFS MRI. Calcified cartilage and SBP abnormalities were assessed at 3D UTE MRI by considering the location of cartilage degradation. The relationship between cartilage degradation grade and abnormalities of calcified cartilage and SBP was assessed using Spearman rank correlation analysis. The association between OCJ abnormalities on PDFS MRI scans and calcified cartilage and SBP abnormalities was analyzed using logistic regression models. Results In total, 143 knees (71 right and 72 left knees) from 143 participants (mean age, 50.8 years ± 17.6 [SD]; 72 male and 71 female participants) were analyzed. On 3D UTE MRI scans, calcified cartilage defects showed a moderate positive correlation with the cartilage degradation grade (ρ = 0.49-0.52; <i>P</i> < .001). Calcified cartilage thinning (ρ = 0.2-0.3; <i>P</i> < .001), SBP irregular thickening (ρ = 0.3-0.35; <i>P</i> < .001), and defects (ρ = 0.34-0.42; <i>P</i> < .001) exhibited a weak positive correlation with the cartilage degradation grade. OCJ abnormalities depicted at PDFS MRI were associated with calcified cartilage and SBP abnormalities (<i>P</i> < .05). Conclusion Calcified cartilage layer and SBP abnormalities at 3D UTE MRI were associated with cartilage degradation and OCJ abnormalities depicted at PDFS MRI. © RSNA, 2024 <i>Supplemental material is available for this article.</i>