The role of 2-18F-fluoro-2-deoxy-D-glucose positron emission tomography in the diagnosis of giant cell arteritis of the temporal arteries.

OBJECTIVE As one of the diagnostic criteria for giant cell arteritis affecting the temporal arteries (temporal arteritis) is still biopsy-proven vasculitis of the affected artery, the aim of our study was to evaluate the value of a non-invasive procedure, 2-(18)F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (F-18-FDG-PET), in the diagnosis of Horton's disease. METHODS During a period of 10 months, 22 consecutive patients with the clinical diagnosis of giant cell arteritis and a positive hypoechogenic halo in duplex sonography were re-examined with F-18-FDG-PET. Six patients had giant cell arteritis involving both the large arteries and the temporal arteries; five patients showed giant cell arteritis only in the large arteries without concomitant involvement of the temporal arteries, and the remaining 11 patients showed only involvement of the temporal arteries. All patients were examined by sonography and F-18-FDG-PET, which was performed before treatment with corticosteroids. RESULTS All patients with positive signs of giant cell arteritis in duplex sonography, i.e. a hypoechogenic halo in the large arteries (thoracic, subclavian, axillary, iliac, aorta), also showed elevated FDG uptake in the same vessels, with complete agreement in the anatomical distribution of changes. When positive sonography was limited to the temporal arteries, FDG-PET was completely negative in the temporal arteries and all other arterial locations. CONCLUSION PET is not yet suitable for the diagnosis of temporal arteritis and therefore cannot replace invasive biopsy. F-18-FDG-PET is well suited to the demonstration of giant cell arteritis in arteries exceeding 4 mm in diameter.