Diagnostic performance of 18 F-FDG PET-CT for large vessel involvement assessment in patients with suspected giant cell arteritis and negative temporal artery biopsy.

OBJECTIVE: The purpose of our study was to assess the diagnostic performance of 18 F-FDG PET-CT for large vessel involvement in patients with suspected giant cells arteritis (GCA) and a negative temporal artery biopsy (TAB).

METHODS: We conducted a retrospective study in a cohort of patients with suspected GCA and negative TAB who underwent an 18 F-FDG PET-CT. Ten vascular segments were studied using a visual score and a semi-quantitative method based on SUVmax ratio with respect to liver uptake. The diagnosis of GCA was established during a mean follow-up of 42 months, based on the presence of clinical symptoms, laboratory results, and imaging data compatible with GCA, good response to corticosteroid therapy, and no differential diagnosis after a follow-up of at least 18 months.

RESULTS: We included 63 patients (30 men and 33 women, aged 67 ± 12 years). 18 F-FDG PET-CT showed large vessel involvement in 22 patients, 14 of whom were finally diagnosed with GCA. Forty-one patients were 18 F-FDG PET-CT negative, 9 of whom were finally diagnosed with GCA. Overall, 18 F-FDG uptake by large vessel yielded 61% sensitivity, 80% specificity, 64% positive predictive value, 78% negative predictive value, and 73% diagnostic accuracy. A significant number of patients were treated by corticosteroids before 18 F-FDG PET-CT. However, corticosteroid therapy did not impact significantly the diagnostic performance, although there was a trend to a lower sensitivity in patients receiving corticosteroid therapy for more than 3 days.

CONCLUSIONS: 18 F-FDG PET-CT is a useful imaging technique to assess large vessel involvement in patients with suspected GCA and negative TAB.