Comparison of 18F-FDG PET/CT findings with current clinical disease status in patients with Takayasu's arteritis

Objective. 18F-fluorodeoxyglucosepositron emission tomography/computed tomography (18F-FDG PET/CT) scanning has been proposed as a new tool to assess disease activity in Takayasu arteritis (TA). We investigated whether 18F-FDG PET/CT findings were consistent with current clinical disease status in patients with TA. Methods. In this cross sectional study, 22 patients with TA were enrolled. Clinical disease activity was assessed by the combination of National Institutes of Health (NIH) criteria, Disease Extent Index-Takayasu (DEI-Tak) score, physician global assessment and 18F-FDG PET/CT scans. Results. At the time 18F-FDG PET/CT scans were taken, the majority of the patients (17122) were using immunosuppressive (IS) drugs, and only four patients had clinically active disease. 18F-FDG PET/CT scans confirmed the presence of active vasculitic lesions in those four patients. In 16 out of 18 patients who were accepted to be in clinical remission, 18F-FDG PET/CT scans were also normal. There were only two patients with discordant results, i.e. active 18F-FDG PET/CT findings despite the lack of clinical activity. Interestingly, clinical exacerbation occurred four weeks later in one of them. Overall sensitivity and specificity of 18F-FDG PET/CT findings for clinical activity were 100% and 88.9%, respectively. Conclusion. We found that 18F-FDG PET/CT findings were generally consistent with clinical disease status in TA. Although use of IS drugs certainly impairs diagnostic accuracy of 18F-FDG PET/CT in TA, this imaging method may still have a potential for confirming remission or detecting disease activity in patients with TA receiving treatment.