Diagnostic Impact of Subcutaneous Edema in Gouty Feet Detected by Dual-Energy Computed Tomography and Ultrasound

Background: The objective of our study was to evaluate the association and frequency of subcutaneous lymphedema in patients with gout primarily affecting the feet. Methods: In 79 patients with acute gout, ultrasound (US) and dual-energy computed tomography (DECT) were performed to assess the presence of subcutaneous edema and extra- and intra-articular gouty deposits. In addition, the diagnostic utility of two post-processing DECT protocols were evaluated, comprising different minimum attenuation thresholds of 150 HU (DECT 150 protocol) and 120 HU (DECT 120 protocol), with the same maximum attenuation threshold (500 HU) and constant kilovoltage setting of tubes A and B at 80 and 140 kVp. Results: Subcutaneous lymphedema was present in 58.2% of patients, with a significant association with extra-articular monosodium urate (MSU) deposits (p < 0.001). Specifically, 97.8% of patients with lymphedema had extra-articular MSU deposits in DECT or US examination, while no cases of lymphedema were found in patients with exclusively intra-articular deposits. The DECT 120 protocol was significantly more sensitive for detecting peripheral MSU deposits (81%) compared to the DECT 150 protocol (34.2%, p < 0.001). Conclusions: Our findings demonstrate that the presence of lymphedema in patients with gout is frequently associated with extra-articular manifestations of the disease.