AB0934 DUAL-ENERGY COMPUTED TOMOGRAPHY IN GOUT PATIENTS: IS IT USEFUL IN GENERAL PRACTICE?

Abstract

Background:Dual-Energy CT (DECT) has high sensitivity and specificity for detecting monosodium urate (MSU) crystal deposition. Although widely used in research, few studies have evaluated the usefulness of DECT in clinical practice.Objectives:To evaluate the use of DECT in a clinical setting and determine its utilityMethods:We retrospectively evaluated the records of all patients referred for DECT scans over a 6.5-year period. Patient charts were reviewed for clinical features.Results:113 patients (17.5/yr) received DECT evaluation at a university hospital over the study period (234 scans). All were referred by rheumatologists. Medical records were available for 69 patients (134 scans), including 44 males and 25 females (mean age 62 (SD, 12.9, range: 34-85 yrs). Mean duration of gout was 6.7 (SD, 8.1) yrs. DECT was ordered to evaluate known gout (36/69, 52.1%), suspected gout (32/69, 46.4%), and suspected calcium pyrophosphate (CPP) disease (1/69, 1.4%). 32/69 (46.4%) of patients were on urate-lowering therapy.61% (42/69) had MSU crystal and none had CPP deposition. Mean MSU volume was 1.6cc (SD, 5.2cc; range: 0.01-35 cc.) The joints imaged were feet/ankles (80/134, 60%) and hands/wrists (53/134, 40%). 23/33 (69.7%) patients with DECT positivity had elevated serum urate (SU) levels >6mg/dL; however, elevated SU was not significantly associated with DECT positivity (odds ratio (OR) 1.9, 95% CI:0.59-5.95, p=0.28).For patients with positive scans, mean gout duration from first known flare was 9.5 (SD, 8.8) yrs.Among patients who had scans completed within 1 yr of the first known gout flare, 1/10 were positive (10%); 4/16 within 2 yrs (25%); and 8/21 within 3 yrs (29.6%).Of patients with positive DECT scans, 24/42 (57%) had symmetric distribution of MSU crystal deposition: 10/24 (42%) hands and 14/24 (58%) feet; with gout duration of 7.9 (SD, 8.0) yrs.Conclusion:DECT was infrequently utilized and only by rheumatologists. Only 60 % of patients referred for DECT scanning because of known or suspected gout had MSU deposition. DECT was uncommonly positive in patients with a 1-3 yr history of gout. When positive, the MSU crystal deposition was symmetrical in most gout patients. DECT scans, while important in furthering our understanding of gout biology, are not routinely used in general practice and often do not provide important decision support information. Establishment of practice guidelines might be important in developing more appropriate utilization of DECT.Disclosure of Interests:Yekaterina Sherman: None declared, Peter Lipsky Consultant of: Horizon Therapeutics, Mark Bramwit: None declared, Naomi Schlesinger Grant/research support from: Pfizer, AMGEN, Consultant of: Novartis, Horizon Pharma, Selecta Biosciences, Olatec, IFM Therapeutics, Mallinckrodt Pharmaceuticals, Speakers bureau: Takeda, Horizon