Significance of Salivary Gland Radioiodine Retention on Post-ablation 131I Scintigraphy as a Predictor of Salivary Gland Dysfunction in Patients with Differentiated Thyroid Carcinoma

Abstract

Purpose We investigated whether 131 I whole-body scintigraphy could predict functional changes in salivary glands after radioiodine therapy. Methods We evaluated 90 patients who received initial highdose (≥3.7 GBq) radioiodine therapy after total thyroidectomy. All patients underwent diagnostic (DWS) and postablation (TWS) 131 I whole-body scintigraphy. Visual assessment of salivary radioiodine retention on DWS and TWS was used to divide the patients into two types of groups: a DWS+ or DWS-group and a TWS+ or TWS-group. Salivary gland scintigraphy was also performed before DWS and at the first follow-up visit. Peak uptake and %washout were calculated in ROIs of each gland. Functional changes (Δuptake or Δwashout) of salivary glands after radioiodine therapy were compared between the two groups. Results Both peak uptake and the %washout of the parotid glands were significantly lower after radioiodine therapy (all p values <0.001), whereas only the %washout were significantly reduced in the submandibular glands (all p values <0.05). For the parotid glands, the TWS+ group showed larger Δuptake and Δwashout after radioiodine therapy than did the TWS-group (all p values <0.01). In contrast, the Δuptake and Δwashout of the submandibular glands did not significantly differ between the TWS+ and TWS-groups (all p values >0.05). Likewise, no differences in Δuptake or Δwashout were apparent between the DWS+ and DWS-groups in either the parotid or submandibular glands (all p values >0.05). Conclusion Salivary gland radioiodine retention on postablation 131 I scintigraphy is a good predictor of functional impairment of the parotid glands after high-dose radioiodine therapy.

Adipose-derived mesenchymal stem cells regenerate radioiodine-induced salivary gland damage in a murine model

“…During the transport of RI into salivary glands, the mechanism of iodine uptake in the SG is similar to that of the thyroid. Therefore, iodine concentration in SG is 20–100 fold higher than that in serum, and the frequency of RI-induced sialadenitis is cumulative 131 I dose-dependent 5 . Furthermore, more than 50% of all patients complain of SG dysfunction associated symptoms and have clinically covert xerostomia or post-therapeutic sialadenitis 5 .…”

“…Therefore, iodine concentration in SG is 20–100 fold higher than that in serum, and the frequency of RI-induced sialadenitis is cumulative 131 I dose-dependent 5 . Furthermore, more than 50% of all patients complain of SG dysfunction associated symptoms and have clinically covert xerostomia or post-therapeutic sialadenitis 5 . Actually, SG dysfunction is one of the most frequent chronic complications after RI therapy 6 .…”

Scintigraphic evaluation of salivary gland function in thyroid cancer patients after radioiodine remnant ablation

“…Moreover, the extent of parotid gland deterioration was significantly more pronounced in patients with RAI retention in parotid glands as revealed by post‐therapeutic scan. Interestingly, in our post‐therapeutic scans, performed in exactly the same setting, there was no RAI uptake in salivary glands following the activity of 3.7 GBq (23).…”

“…An interesting study examining the relationship of salivary gland functional deterioration with the RAI uptake in salivary glands on post‐therapeutic whole‐body scan was published by Jo et al (23) in 2014. The authors analysed, using salivary gland scintigraphy, the changes in salivary gland uptake and excretion in 90 patients before and 5 to 14 months (mean 7.4) after thyroid remnant ablation.…”

“…In several carefully conducted studies (17, 20‐24), salivary gland scintigraphy or sialometry has been used for quantitative assessment of possible salivary gland dysfunction after RAI administration, sometimes reporting dose‐dependent functional changes, predominantly in parotid glands. In these reports, widely varying and usually higher activities (ranging from 3.7 to 33.9 GBq) have been used.…”