Temporal (67)gallium uptake is increased in temporal arteritis

Objective. We evaluated temporal (67)gallium (Ga) uptake in temporal arteri tis (TA) and the contribution of Ga scans to the diagnosis of TA. Methods. Ga scans were performed prospectively in 19 patients with biopsy-proven TA and five TA patients with negative temporal artery biopsy. controls were 18 elderly patients undergoing Ga scans for various inflammatory diseases. Th e temporal region of interest on head profiles was defined for comparison o f uptake with a control parietal region of the same area. The Ga uptake rat io (GaUR) [(temporal region - parietal region)/parietal region] was evaluat ed for each temple by a computer and intra- and intergroup comparisons were made. Results. GaUR was significantly higher in biopsy-proven TA patients (0.35 +/- 0.19) and biopsy-negative TA patients (0.31 +/- 0.03) than in con trols (0.18 +/- 0.12) (P < 0.001), independently of recent temporal artery biopsy or short-duration steroid therapy. High GaUR (> 0.4) had a 94% speci ficity and a 90%; positive predictive value for TA diagnosis. After 6 month s of steroid therapy, when patients were in remission, GaUR returned to bas eline. Conclusion. Ga is specifically incorporated into the temporal area i n TA patients which may be due to the granulomatous vasculitic process. Ga uptake ceases during remission. A high GaUR may contribute to TA diagnosis in temporal artery biopsy-negative patients and its role in the diagnosis o f other localizations of the disease requires further evaluation.