Dual-Energy Computed Tomography of the Knee, Ankle, and Foot: Noninvasive Diagnosis of Gout and Quantification of Monosodium Urate in Tendons and Ligaments.

Gout is a true crystal deposition arthropathy caused by the precipitation of monosodium urate into joints and periarticular soft tissues. It is the most common inflammatory arthropathy in men and women of older age with a male-to-female ratio of 3 to 8:1. The disease may progress from asymptomatic hyperuricemia through symptomatic acute gout attacks with asymptomatic periods into chronic symptomatic tophaceous gout. Although invasive arthrocentesis and demonstration of monosodium urate crystals on polarized light microscopy is definitive for the diagnosis of gout, dual-energy computed tomography (CT) allows for noninvasive visualization and reproducible volume quantification of monosodium urate crystals. Based on the high diagnostic performance, dual-energy CT has been included in the 2015 American College of Rheumatology/European League Against Rheumatism Collaborative Initiative Classification Criteria for Gout. Increasing evidence indicates the usefulness of dual-energy CT to guide the management of patients with suspected gout and monitor the effectiveness of urate-lowering medical therapy.