Rheumatoid arthritis: evaluation with contrast-enhanced CT with digital bone masking.

The purpose of this HIPAA-compliant study was to prospectively evaluate the feasibility of contrast material-enhanced computed tomography (CT) with digital bone masking for the evaluation of synovitis and tenosynovitis in patients with rheumatoid arthritis. Four patients with rheumatoid arthritis and findings at magnetic resonance (MR) imaging were evaluated after informed consent for this institutional review board-approved study was obtained. To improve the conspicuity of synovial enhancement, postcontrast CT was performed with a relatively low kilovoltage and high iodine concentration and precontrast images were used as a subtraction mask to eliminate high-attenuation cortical bone contours. Moderate to high agreement between CT and MR imaging findings for synovitis and tenosynovitis was demonstrated, which suggests that this technique may be an acceptable alternative to MR imaging in the evaluation of rheumatoid arthritis. (c) RSNA, 2009.