The relationship between limited MRI section analyses and volumetric assessment of synovitis in knee osteoarthritis.

Aim: To assess whether simple, limited section analysis can replace detailed volumetric assessment of synovitis in patients with osteoarthritis (OA) of the knee using contrast-enhanced magnetic resonance imaging (MRI).
Materials and Methods: Thirty-five patients with clinical and radiographic OA of the knee were assessed for synovitis using gadolinium-enhanced MRI. The volume of enhancing synovium was quantitatively assessed in four anatomical sites (the medial and lateral parapatellar recesses, the intercondylar notch and the suprapatellar pouch) by summing the volumes of synovitis in consecutive sections. Four different combinations of section analysis were evaluated for their ability to predict total synovial volume.
Results: A total of 114 intra-articular sites were assessed. Simple linear regression demonstrated that the best predictor of total synovial volume was the analysis containing the inferior, mid and superior sections of each of the intra-articular sites, which predicted between 40-80% (r(2) = 0.396, p < 0.001 for notch; r(2) = 0.818, p < 0.001 for medial parapatellar recess) of the total volume assessment.
Conclusions: The results suggest that a three-section analysis on axial post-gadolinium sequences provides a simple surrogate measure of synovial volume in OA knees.