SAT0406 COMPUTED TOMOGRAPHIC MAPPING OF SPINAL AND VASCULAR URATE DEPOSITION IN THE ABDOMEN WITH CORRELATION TO URIC ACID LEVEL
Authors: Juvel Lee, Waleed Abdellatif, Sunghan Jung, Ahmed Negida, Bo Gong, Savvas Nicolaou
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Gout is characterized by accumulation of monosodium urate (MSU) in joints and soft tissues. Gout prevalence is about 1-5% in the western world, predominantly in elderly men. Accurate diagnosis of gout is paramount in managing disease progression and guiding treatment. A meta-analysis in 2018 showed that Dual-Energy CT (DECT) has high sensitivity, specificity and diagnostic accuracy in MSU detection. MSU deposition outside 'classic' extremities has been scarcely investigated yet may be a potential indicator of tophus burden and impending clinical deterioration. <h3>Objectives:</h3> 1. Anatomical mapping of gout deposition in the abdomen (vessels, solid organs and lumbosacral spine). 2. Determine correlation between uric acid level and vascular, solid organ and spinal MSU deposition. <h3>Methods:</h3> Retrospective analysis of all DECT abdomen and pelvis scans done in our institution (from January 2007 to July 2018). The inclusion criteria were: males &gt; 50 years with high or normal uric acid level. All cases were then assessed by 2 radiologists with extensive experience in DECT for MSU deposits. Validated dual-energy gout analysis software was used. <h3>Results:</h3> 235 DECT cases met the inclusion criteria. Medical Record document review showed no diagnosis of gout in any patient in the sample. By the time this abstract was submitted, 166 cases were reviewed. The analyzed sample (n = 166), showed MSU deposits (1 or more deposits) in the abdominal aorta (n = 48/166; 28.92%), abdominal vessels other than aorta (n = 57/166; 34. 34%) and lumbosacral spine (n = 15/166; 9.04%). No deposits were detected in the solid abdominal organs (n = 0/166; 0%). There was a statistically significant positive correlation between uric acid level and spinal deposits (r= 0.22, P= 0.004). No significant correlation between uric acid level and aortic (P= 0.86) or vascular deposits (P= 0.19). Regression analysis showed uric acid levels can't significantly predict the presence of aortic, vascular or spinal deposits. <h3>Conclusion:</h3> Computed tomographic mapping of MSU deposits was positive in the abdominal aorta, other abdominal vessels and lumbosacral spine in patients with normal or high uric acid levels who were asymptomatic for gout. Uric acid level was positively correlated with spinal gout, but not with aortic or vascular gout. Interestingly, uric acid levels can't significantly predict the presence of aortic, vascular or spinal gout. Larger sample size, wider variation in uric acid levels are still needed. <h3>References</h3> [1] Yu, Z., Mao, T., Xu, Y., Li, T., Wang, Y., Gao, F., &amp; Sun, W. (2018). Diagnostic accuracy of dual-energy CT in gout: a systematic review and meta-analysis. Skeletal radiology, 1-7. [2] Barazani, S. H., Chi, W., Pyzik, R., Jacobi, A., O'Donnell, T., Fayad, Z.,. .. &amp; Ali, Y. (2018). Detection of Uric Acid Crystals in the Vasculature of Patients With Gout Using Dual-Energy Computed Tomography. Circulation, 138(Suppl_1), A11821-A11821. [3] Gamala, M., Linn-Rasker, S. P., Nix, M., Heggelman, B. G. F., van Laar, J. M., Pasker-de Jong, P. C. M.,. .. &amp; Klaasen, R. (2018). Gouty arthritis: decision-making following dual-energy CT scan in clinical practice, a retrospective analysis. Clinical rheumatology, 1-6. [4] Chew, N., &amp; Cho, J. (2018). Dual-energy CT for the diagnosis of sacroiliac and spinal gout. Joint Bone Spine. <h3>Disclosure of Interests:</h3> Juvel Lee: None declared, Waleed Abdellatif: None declared, Sunghan Jung: None declared, Ahmed Negida: None declared, Bo Gong: None declared, Savvas Nicolaou Grant/research support from: The Department of Radiology, Vancouver General Hospital has a Master Research Agreement with Siemens Healthcare, Forcheim, Germany (non-pharmaceutical company).