Origin and location on the oral activity in sequential salivary gland scintigraphy with 99mTc-pertechnetate

Conflicting views exist regarding the origin and location of the oral radioactivity seen in salivary gland scintigraphy with 99mTc-pertechnetate. The normal accumulation of oral activity was studied in a series of healthy subjects by sequential scintigraphy (anterior and lateral views) after intravenous injection of 2 mCi of 99mTc-pertechnetate. Ligation of the parotid ducts and/or cannulation of the submandibular ducts, which prevented their secretions from reaching the oral cavity, established that the oral activity was due entirely to radioactive saliva secreted by the parotid and submandibular glands. Pertechnetate mouthwash studies confirmed that radioactive saliva is absorbed to oral mucosa and that adsorption to the lingual mucosa in the major contributor to the oral activity. Pertechnetate uptake in sublingual and minor salivary glands of the oral cavity was not visualized, thereby invalidating scintigraphy in the study of these glands. In the diagnosis of salivary gland disorders, oral activity is a useful indicator of major salivary gland function.