We simultaneously assessed ultrasonography (US) and magnetic resonance imaging (MRI) in comparison with histopathological changes in the knee joints of long-lasting arthritis patients.
We studied 15 patients with rheumatoid arthritis and 5 patients with osteoarthritis, who underwent total knee arthroplasty. On the day before surgery, the joints were examined by US and contrast-enhanced MRI. In US, synovitis was graded with 0-3 grey scale (GSUS) and power Doppler (PDUS). In MRI, synovitis was graded according to OMERACT-RAMRIS (grade 0-3). Synovial tissue samples were obtained during arthroplasty and evaluated on the basis of inflammatory cell infiltrates (grade 0-3), synovial lining layer thickness (grade 0-3) and vascularity (grade 0-3).
Positive findings of PDUS and contrast-enhanced MRI were 45% and 85% of 20 operated joints, respectively. GSUS, PDUS and MRI synovitis were well correlated with overall histopathological grades of synovitis (Spearman correlation coefficients 0.48, 0.84 and 0.48, p<0.05, p<0.01 and p<0.05, respectively). Moreover, positive PDUS findings were closely associated with all pathological comportments of synovitis including inflammatory cell infiltrates, synovial lining layer thickness and vascularity.
The present study revealed that positive PDUS findings more faithfully illustrated active synovitis than MRI, whereas contrast-enhanced MRI was more sensitive in detecting synovitis in patients with long-lasting arthritis. It is important to understand distinct features of the both modalities for clinical assessment of chronic joint diseases.