Synovitis assessed on static and dynamic contrast-enhanced magnetic resonance imaging and its association with pain in knee osteoarthritis: A cross-sectional study

Objectives To investigate the association between pain and peripatellar-synovitis on static and dynamic contrast-enhanced MRI in knee osteoarthritis. Methods In a cross-sectional setting, knee synovitis was assessed using 3-Tesla MRI and correlated with pain using the knee injury and osteoarthritis outcome score (KOOS). Synovitis was assessed in the peripatellar recesses with: (i) dynamic contrast-enhanced (DCE)-MRI, using both pharmacokinetic and heuristic models, (ii) contrast-enhanced (CE)-MRI, and (iii) non-CE-MRI. The DCE-MRI variable IRExNvoxel was chosen as the primary variable in the analyses. Results Valid data were available in 94 persons with a mean age of 65 years, a BMI of 32.3 kg/m² and a mean Kellgren-Lawrence grade of 2.5. IRExNvoxel showed a statically significant correlation with KOOS-Pain (r = -0.34; p = 0.001), as was the case with all DCE-variables but one. Correlations between static MRI-variables and KOOS-Pain ranged between -0.21 < r < -0.29 (p < 0.040). Intraclass correlation coefficients ranged between 0.90-0.99 for the heuristic and 0.66-0.93 for the pharmacokinetic DCE-MRI variables. Conclusions The results confirm an association between peripatellar-synovitis and pain in KOA. Overall, DCE-MRI showed stronger correlations with KOOS-Pain compared to static MRI. DCE-MRI analyses were highly reproducible and have the potential to be used to further investigate the role of inflammation and perfusion in KOA.