Disease Activity in Patients With Takayasu's Arteritis: Evaluation of 18f-fdg Pet/ct and Angiotomography Performances

Objective To evaluate the performance of 18F-FDG PET/CT in assessing disease activity in patients with Takayasu arteritis (TA), by comparing 18F-FDG PET/CT findings with clinical and laboratory parameters, as well as vascular alterations observed on angiotomography (CTA). Methods In this cross-sectional study, 19 patients with TA were evaluated for clinical, laboratory and imaging activity (CTA and 18F-FDG PET/CT). Vascular activity on CTA was defined by the presence of vessel wall thickening and/or double-ring signs. PET vascular activity score (PETVAS) and maximum standardized uptake value (SUVmax) were used to assess ¹⁸F-FDG PET/CT activity. Results Patients with clinical activity demonstrated greater aortic wall thickening compared to those in remission [median (range): 2.9 mm (0–6) vs. 0 mm (0–5.5); p  = 0.02]. In contrast, no significant difference was observed in vessel wall thickening of the aortic branches. Aortic wall thickening greater than or equal to 3.3 mm showed a sensitivity of 45% and specificity of 86% to predict disease activity. No significant differences in SUVmax values and PETVAS scores were observed between patients with active disease and those in remission. Vessel wall thickening values on CTA [median, min. and max. 1.8 (0–6) mm vs. 0 (0-5.3) mm, p = 0.013] were significantly higher in patients with an 18F-FDG PET/CT uptake score ≥ 2. Conclusion The 18F-FDG PET/CT did not demonstrate good performance in assessing disease activity based on clinical criteria, but showed association with vessel wall thickening on CTA, which appears to be a useful marker for disease activity in the aorta.