Comparison of F18-FDG PET/CT findings with current clinical disease status in patients with Takayasu's arteritis

OBJECTIVES: 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (F-18 FDG PET/CT) scanning has been proposed as a new tool to assess disease activity in Takayasu Arteritis (TA). We investigated whether F-18 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 F-18 FDG PET/CT scans.

RESULTS: At the time F-18 FDG PET/CT scans were taken, the majority of the patients (17/22) were using immunosuppressive (IS) drugs, and only four patients had clinically active disease. F-18 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, F-18 FDG PET/CT scans were also normal. There were only two patients with discordant results, i.e. active F-18 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 F-18 FDG PET/CT findings for clinical activity were 100% and 88.9%, respectively.

CONCLUSIONS: We found that F-18 FDG PET/CT findings were generally consistent with clinical disease status in TA. Although use of IS drugs certainly impairs diagnostic accuracy of F-18 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.