Objective: To evaluate the potential utility of dual energy CT scan (DECT) in assessing urate deposits among patients with tophaceous gout and computerized quantification of tophus volume in peripheral joints.
Methods: We included 20 consecutive patients with tophaceous gout and ten control patients with other arthritic conditions. DECT scans were performed using a renal stone color-coding protocol that specifically assessed the chemical composition of the material (i.e. urate colored in red, calcium colored in blue). Using an automated volumetric assessment of DECT, we measured the volume of urate deposits in all peripheral joint areas.
Results: All 20 patients with gout showed red color-coded urate deposits on their DECT scans, whereas none of 10 controls showed urate deposits. DECT scans revealed a total of 440 areas of urate deposition in 20 patients, whereas physical examination showed 111 areas of urate deposition (mean, 22 vs. 6 per patient, respectively, p=0.0001). Total urate volume in a given patient ranged from 0.63 cm3 to 249.13 cm3, with a mean of 40.20 cm3.
Conclusions: DECT scans can produce obvious color displays for urate deposits and help identify subclinical tophus deposits. Furthermore, tophus volume can be measured by DECT scans through an automated volume estimation procedure.