Power Doppler sonography with and without echo-enhancing contrast agent and contrast-enhanced MRI for the evaluation of rheumatoid arthritis of the shoulder joint:: differentiation between synovitis and joint effusion

Objective: To evaluate patients with clinically active rheumatoid arthritis (RA) of the shoulder for joint effusion and synovitis using conventional sonography, power Doppler (PD) sonography with and without echo-enhancing contrast agent, and contrast-enhanced MRI. Design and patients: Twenty-four patients (mean age 64 years) with known RA had one symptomatic shoulder evaluated by conventional gray-scale sonography and PD sonography before and after intravenous administration of the echo-enhancing contrast agent Levovist (300 mg/ml, 2.5 g). The degree and extent of the altered echo pattern in the subacromial bursa, axillary recess and glenohumeral joint seen by conventional gray-scale sonography and the intensity of vascular signals of PD sonography were compared with the findings of MRI obtained with T2-weighted turbo spin-echo sequences and contrast-enhanced T1-weighted fat-saturated spin-echo sequences. MRI was evaluated by two readers in consensus without knowledge of the sonographic findings. Results: MRI, which was used as the reference examination, detected joint effusion in 71% (17/24) and synovitis in 92% (22/24) of the patients. Conventional sonography revealed an abnormal articular echo pattern in 96% (23/24) of the patients, especially in the axillary recess and subacromial bursa, but failed to attribute the altered echo pattern to either fluid or specific synovitis. PD sonography allowed a specific diagnosis of synovitis in 33% (8 patients), which increased to 50% (12 patients) after administration of an echo-enhancing contrast agent. In 42% (10/24) of the patients, the findings of synovitis demonstrated by MRI corresponded to an altered echo pattern by conventional sonography, but vascular signals were absent by PD sonography with or without echo-enhancing contrast agent. Conclusions: Using MRI as the "gold standard", PD sonography with and without echo-enhancing contrast agent cannot reliably identify synovitis or distinguish synovial inflammation from effusion in the shoulder joint.