The usefulness and limitations of combined Tc-99m pertechnetate and Ga-67 citrate imaging of salivary gland disorders

The usefulness of combined Tc-99m and Ga-67 scans in diagnosing salivary gland disorders was evaluated in a total of 31 patients. Out of 6 patients with Warthin's tumor, 4 showed a typical pattern of high-activity in the gland with retention of Tc-99m, but without an affinity for Ga-67. Out of 9 patients with pleomorphic adenoma, 8 showed a 'cold' area in the tumor by Tc- 99m and 5 of the 9 patients had accumulated Ga-67. Five of 6 patients with malignant tumor showed an affinity for Ga-67. Nine of 10 patients with sialadenitis showed diffuse uptake of both Tc-99m and Ga-67 in the involved gland. Combined Tc-99m and Ga-67 imaging was useful in detecting the cases of Warthin's tumor and sialadenitis (90% sensitivity and 89% specificity for sialadenitis), but the study had limitations in differentiating malignant tumors from benign tumors (66% sensitivity and 84% specificity). However, Ga- 67 imaging showed a 91% negative predictive value. A negative scan could almost rule out the possibility of malignant disease of the salivary gland.