What are the imaging findings in gout?
Imaging shows crystal deposition within the periarticular soft tissues, most commonly involving the first metatarsophalangeal (MTP) joints, but also possibly within bones, tendons, and bursae, with an asymmetrical polyarticular distribution most often in the hands and feet. Characteristic changes seen on radiographs occur in the chronic stages of the disease. These include eccentric “punched out” juxtaarticular erosions, which are more marginal than those seen in RA, typically with sclerotic margins and overhanging edges of cortical bone. Bone mineralization is normal, and joint spaces are generally preserved until late in the disease course. Earlier findings are nonspecific and include soft tissue swelling, sometimes in a “lumpy bumpy” pattern, and joint effusions. The areas of soft tissue swelling (i.e., tophi) may appear radiodense on radiography due to crystal deposition. Soft tissue calcifications may also be seen and are more often associated with concomitant renal disease. On MRI, tophi usually have low-intermediate T1-weighted signal intensity and variable T2-weighted signal intensity relative to skeletal muscle and enhance.