AB1075 Seronegative arthropathies: Value of dual-energy CT for differential diagnosis

Background Seronegative Oligo/Polyarthritis combines a set of diseases including gout as a possible differential diagnosis. The identification of monosodium urate crystals is the gold standard for the proof of gout. However, the puncture of small finger and toe joints maybe a challenge and is therefore often not applicable. Methods A retrospective analysis of 49 patients was used to investigate the value of Dual-Energy CT for differential diagnosis in patients with seronegative arthropathies. Puncture and analysis of the joint fluid was possible in 15 patients, whereas Dual-Energy CT without puncture could be performed in the remaining 34 patients. Results In the first group of patients (n=15), where a crystal analysis was available, urate crystals could be indentified in 14 and Dual-Energy CT investigation confirmed monosodium urate depositions in 11 of these patients.In 3 cases with positive urate crystal detection in joint fluid gout-CT was negative.In one case pyrophosphate crystals were identified and no urate depositions in gout-CT could be detected. In the second group (n=34) joint puncture could not be performed as the affected joints were small finger and toe joints.21 of these patients revealed urate depositions in Dual-Energy CT. In these cases the diagnosis of gout was confirmed and appropriate therapy could be started. 17 out of these 21 patients had elevated uric acid levels. Conclusions Dual-Energy CT can be applied as a tool for diagnosing gout in patients with seronegative inflammatory arthropathy especially in the case of polyarticular joint involvement and no possibility of joint puncture. References W Zhang, M Doherty, E Pascual et al. Eular evidence based recommendations for gout. Part I: Diagnosis.Report of a task force of the standing committee for international clinical studies including therapeutics/ESCISIT). Ann Rheum Dis 2006;65:1301-1311 W Zhang, M Doherty, T Bardin et al. Eular evidence based recommendations for gout. Part II: Management.Report of a task force of the standing committee for international clinical studies including therapeutics/ESCISIT). Ann Rheum Dis 2006;65:1312-1324 N Dalbeth, B Clark, K Gregory et al. Mechanisms of bone erosion in gout: a quantitative analysis using plain radiography and computed tomography. Ann Rheum Dis 2009; 68:1290-1295 RGThiele,N Schlesinger. Diagnosis of gout by ultrasound. Rheumatology 2007;46:1116-1121 JC Gerster, M Landry, G Rivier. Computes Tomographic Imaging of Subcutaneous Gouty Tophi. Clin Rheumatol 1998;17:62-64 S Nicolaou, CJ Yong-Hing, S Galea-Soler. Dual Energy CT as a Potential New Diagnostic Tool in the Management of Gout in the Acute Setting. AJR 2010;194:1072-1078 G.Strau, M. Mustak, M Kasper. Dual-Energy-Computertomografie (article in German). Jatros Orthopadie & Rheumatologie 5/2011 Disclosure of Interest None Declared