A novel model to assess disease activity in Takayasu arteritis based on 18F-FDG-PET/CT: a Chinese cohort study.

OBJECTIVE: To investigate the utility of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in assessing disease activity in Takayasu arteritis (TA). METHODS: Ninety-one patients with TA were recruited from a Chinese cohort. Clinical data, acute-phase reactants and 18F-FDG-PET/CT findings were simultaneously recorded. The value of using 18F-FDG-PET/CT to identify active disease was evaluated, using ESR as a reference. Disease activity assessment models were constructed and concordance index (C-index), net reclassification index (NRI), and integrated discrimination index (IDI) were evaluated to compare the benefits of the new modes with ESR and the Kerr score. RESULTS: In total, 64 (70.3%) cases showed active disease. Higher levels of ESR and CRP, and lower IL-2 receptor (IL-2R) levels were observed in active cases. 18F-FDG-PET/CT parameters measured by determining the standard uptake value (SUV), including SUVmean, SUVratio1, SUVratio2, sum of SUVmean and sum of SUVmax, were significantly higher in active disease groups. The C-index threshold of ESR to indicate active disease was 0.78 (95% CI: 0.69, 0.88). The new activity assessment model combining ESR, sum of SUVmean and IL-2R showed significant improvement in C-index over the ESR method (0.96 vs 0.78, P < 0.01; NRI 1.63, P < 0.01; and IDI 0.48, P < 0.01). The new model also demonstrated modest superiority to the Kerr score assessment (0.96 vs 0.87, P = 0.03; NRI 1.19, P < 0.01; and IDI 0.33, P < 0.01). CONCLUSIONS: A novel 18F-FDG-PET/CT-based method that involves combining the sum of SUVmean with ESR score and IL-2R levels demonstrated superiority in identifying active TA compared with conventional methods.