Gout is an inflammatory arthritis caused by the deposition of monosodium urate crystals in joints and surrounding tissues, most commonly affecting the first metatarsophalangeal joint of the big toe. On musculoskeletal ultrasound, gout produces several characteristic findings: the double contour sign, a bright, echogenic line on the surface of the articular cartilage representing crystal deposits; tophi, which appear as heterogeneous, hyperechoic aggregates surrounded by a hypoechoic halo; and joint effusion. Ultrasound has become an increasingly important tool for diagnosing gout because it can detect crystal deposits non-invasively, sometimes even before the first clinical attack.
Sonography Term