OBJECTIVES To determine the diagnostic and therapeutic impact of dual-energy computed tomography (DECT) in gout. METHODS Forty-three patients with (n = 20) and without a history of gout (n = 23) showing non-specific soft tissue deposits underwent DECT after unrewarding arthrocentesis. Two blinded, independent readers evaluated DECT for the presence of urate crystals. Clinical diagnosis, clinically suspected urate crystal locations, diagnostic thinking and therapeutic decisions were noted before and after DECT. Clinical 1-month follow-up was obtained. RESULTS DECT showed urate in 26/43 patients (60 %). After DECT, clinical diagnosis of gout was withdrawn in 17/43 (40 %) and was maintained in 16/43 patients (37 %). In 10/43 patients (23 %) the diagnosis was maintained, but DECT revealed urate in clinically unsuspected locations. In 23/43 patients (53 %), a treatment-change based on DECT occurred. Changes in diagnostic thinking occurred more frequently in patients without a history of gout (p < 0.001), changes in therapeutic decisions more frequently in patients with a history of gout (p = 0.014). Clinical follow-up indicated beneficial effects of DECT-based diagnoses in 83 % of patients. CONCLUSIONS In patients with or without a history of gout and a recent suspicion for gouty arthritis with an unrewarding arthrocentesis, DECT has a marked diagnostic and therapeutic impact when hyperdense soft-tissue deposits are present. KEY POINTS • This study evaluates the concept of evidence-based radiology • In patients with suspected gout, DECT can help clinicians make the diagnosis • DECT has a marked impact on therapy • Clinical follow-up after 1 month indicated reliable results of DECT.