Salivary glands ultrasound examination after radioiodine-131 treatment for differentiated thyroid cancer.

Abstract

The most important side effect of radioiodine ((131)I) therapy is sialoadenitis and xerostomy. To evaluate by ultrasound (US) parotid and submandibular glands after (131)I therapy for differentiated thyroid cancer (DTC). Seventy-six subjects thyroidectomized for DTC submitted to salivary glands US examination. Forty-three of them had been previously treated with (131)I: 22 with 1.11 GBq (30 mCi) for remnant ablation, and 21 with higher doses [up to 44.4 GBq (1200 mCi)] for metastases. Thirty-three subjects studied before (131)I therapy served as controls. Parotid and submandibular volume, homogeneity, and echogenicity were determined. (131)I-treated patients filled a questionnaire about sialoadenitis symptoms. Parotid gland volume was significantly higher in treated patients (28.3±16.2 ml) than in untreated patients (20.7±10.4 ml, p=0.0154) and related to the time from last (131)I therapy. Three had parotid volume <1.5 ml and complained severe xerostomy. Submandibular gland volume was similar in treated (11.2±7.6 ml) and untreated patients (8.6±4.2 ml, p=0.0602). Homogeneity and echogenicity were similar in treated and untreated patients. Sialoadenitis symptoms were reported in 26% and were related to the (131)I cumulative dose. Symptoms were not related to gland volume. Hypoechogenicity and inhomogeneity of the parotids were more frequent in patients with salivary stickiness. Parotid, but not submandibular, volume is increased after (131)I treatment depending on the received activity and the time from irradiation but not on sialoadenitis symptoms. Xerostomy is associated to gland atrophy at US.