Katrina Nesta Glazebrook MBChB, Presenter: Nothing to Disclose

Naveen Srinivasa Murthy MD, Abstract Co-Author: Nothing to Disclose

Luis Guimaraes MD, Abstract Co-Author: Nothing to Disclose

Tim Bongartz MD, Abstract Co-Author: Nothing to Disclose

Joel Garland Fletcher MD, Abstract Co-Author: Research grant, Siemens AG

Cynthia H. McCollough PhD, Abstract Co-Author: Research grant, Siemens AG

Our purpose was to evaluate the accuracy of dual energy CT (DECT) in demonstrating the presence of articular or peri-articular monosodium urate (MSU) crystals in patients with arthralgia and suspected gout using joint aspiration results as the reference standard.

Consecutive patients who underwent both an articular DECT scan for a clinical suspicion of gout between April 2008 and February 2010 and subsequent successful aspiration of the symptomatic joint within one month were included. The exams were performed using a dual-source CT scanner operating in dual-energy mode (80/140 kV). Reconstructed images were analyzed using a commercially available software tool, which uses a three-material decomposition algorithm to identify uric acid. Two musculoskeletal radiologists classified the exam as positive or negative for the presence of MSU crystals, grading the presence of artifacts/diagnostic confidence using a 4-point scale (1 = no artifacts, high confidence; 4 = severe artifacts, non-diagnostic). Sensitivity, specificity and multi-reader concordance coefficient were calculated. Reference standard for MSU presence was the result of subsequent joint aspiration.  

One hundred DECT scans were performed in 94 patients, with 43 patients undergoing subsequent joint fluid aspiration within the catchment period. In 12 patients, joint fluid was insufficient for analysis, leaving 31 patients in the study cohort. Of these, 12 had aspirations positive for MSU crystals, while 19 were negative. DECT sensitivity was 92% (11/12) and 100% for Readers 1 and 2, respectively. Specificity was 89% (17/19) and 79% (15/19), respectively. There was almost perfect agreement between readers (κ = 0.81). Mean artifacts/diagnostic confidence scores was 1.4 for both readers. In 14 additional patients undergoing aspiration outside of the catchment period, DECT results were concordant with aspiration results in all cases.

DECT provides 3-D volumetric assessment of gout burden and may eventually replace invasive joint aspiration in most patients suspected to have gout.

With its accuracy and non-invasive character, DECT seems to be beneficial for patients with suspected gout, as joint aspiration is invasive, frequently non-feasible and operator/laboratory dependent.

Glazebrook, K, Murthy, N, Guimaraes, L, Bongartz, T, Fletcher, J, McCollough, C, Non-Invasive Identification of Intra-articular and Peri-articular Uric Acid Crystals with Dual Energy Computed Tomography: Has a New Gold Standard for Gout Been Found?.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9012359.html