SAT0343 Utility of Vascular Findings by PET/CT Scan in The Diagnosis and Activity Assessment of Takayasu Arteritis

BackgroundTakayasu arteritis (TA) is a large-vessel vasculitis predominantly affecting the aorta and its main branches. Assessing disease activity is difficult and mainly based on the clinical findings, levels of acute phase reactants and angiography, but these items generally do not correlate wellObjectivesThe aim of the this study was to investigate the role of PET/CT in the diagnosis of the disease and assessing disease activity in TAMethodsThirty TA patients fulfilling ACR criteria underwent FDG-PET/CT were retrospectively assessed. Disease activity was defined according to NIH criteria. A nuclear physician who was blinded to clinical and laboratory data examined all PET/CT scans. PET/CT scans were considered negative if vascular FDG uptake was lower than liver uptake, if there was moderate (equivalent to that of liver) or marked (more than liver) FDG uptake in at least one vessel area, the scan was considered positive for vasculitis. The levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured concomitantly. The correlation between CRP and ESR with SUVmax values of vessels was investigated. Disease activity with the NIH cirteria, CRP levels and ESRs were compared in subjects with or without positive PET/CT scans. ROC curve analyses were performed to assess the sensitivity and specificity of CRP and ESR according to PET/CT positivityResultsPET/CT was performed for diagnostic purposes early in the disease course in 9 subjects and to assess disease flare in 21 subjects on follow-up. The rate of a positive PET/CT examination tended to be higher in diagnostic/early use (88.9% positive) compared with use for flare-assessment (61.9% positive), although the difference was not significant (Fisher=0.2). Median CRP and ESR tended to be higher in PET/CT positive patients compared with PET/CT negative subjects (median CRP 19 vs. 14, p=0.16; mean ESR 59.8±36.5 vs. 35.2±19.7, p=0.07). ROC curve analysis showed an ESR of 38 mm/h or higher was 68.4% sensitivity and 66.7% specificity to predict a positive PET/CT examination (positive and negative predictive values 81.6% and 50%). A CRP of 14.5 mg/L or higher was 66.7% and 55.6% specific to predict a positive PET/CT examination (positive and negative predictive values 77.8% and 41.7%). While CRP was significantly correlated with mean SUVmax value of aorta (r=0.41, p=0.02), ESR was weakly correlated with SUVmax value of aorta (r=0.3, p=0.13). There was moderate agreement between PET-CT an