Temporal 67gallium uptake is increased in temporal arteritis

We evaluated temporal 67gallium (Ga) uptake in temporal arteritis (TA) and the contribution of Ga scans to the diagnosis of TA.

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. The temporal region of interest on head profiles was defined for comparison of uptake with a control parietal region of the same area. The Ga uptake ratio (GaUR) [(temporal region - parietal region)/parietal region] was evaluated for each temple by a computer and intra- and intergroup comparisons were made.

GaUR was significantly higher in biopsy-proven TA patients (0.35+/-0.19) and biopsy-negative TA patients (0.31+/-0.03) than in controls (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% specificity and a 90% positive predictive value for TA diagnosis. After 6 months of steroid therapy, when patients were in remission, GaUR returned to baseline.

Ga is specifically incorporated into the temporal area in 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 of other localizations of the disease requires further evaluation.