Dual-energy computed tomography for monitoring the effect of urate-lowering therapy in gouty arthritis.

OBJECTIVE

To investigate the relationships between changes in serum urate levels and dual-energy computed tomography (DE-CT) results during urate-lowering therapy (ULT) and to investigate the effects of treatment duration and drugs on changes in DE-CT results.

METHODS

Forty-four patients diagnosed with gout were enrolled in this investigation. DE-CT was conducted on the foot at baseline and the end of follow-up (6-24 months). Crystals were classified as: (i) L, number of large crystals with diameter ≥ 3 mm; (ii) S, number of small crystals with diameter < 3 mm; (iii) T, total number of crystals; and (iv) Vmax, volume of the maximal crystal.

RESULTS

Number of urate crystals (L, S as well as T) and Vmax decreased significantly through ULT. Significant decrease of urate crystal numbers and/or Vmax was observed in different follow-up groups, and the decrease in serum urate levels was positively related to the decrease of T (r = 0.43, P = 0.04) and Vmax (r = 0.63, P = 0.04). Moreover, analysis of covariance results demonstrated significant effects of treatment duration and serum urate levels on results of DE-CT.

CONCLUSION

Both urate crystal numbers and Vmax decreased significantly during ULT. Additionally, ULT duration and serum urate levels had significant effects on the decrease of Vmax and number of large crystals measured by DE-CT.