Asymmetric I-131 uptake in the submandibular gland in the setting of thyroid carcinoma

I-131 scans may demonstrate asymmetric submandibular signal, secondary to physiologic or pathophysiologic processes. CT correlation may help distinguish metastatic lymphadenopathy from other causes of abnormal uptake. In this report, 2 patients with history of thyroid carcinoma underwent follow-up I-131 scintigraphy. Asymmetric submandibular uptake led to further evaluation with CT. In both cases, the asymmetric uptake was related to alterations of normal physiologic uptake and excretion in the submandibular gland, by different mechanisms. In the first case, excretion was impaired because of chronic obstruction. In the second case, asymmetry was due to chronic disease with impaired function on the contralateral side.