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. 2021 Jan-Mar;36(1):25-31.
doi: 10.4103/ijnm.IJNM_158_20. Epub 2021 Mar 4.

Early Quantification of Salivary Gland Function after Radioiodine Therapy

Karan Singh Tanwar  1 , Nivedita Rana  1 , Bhagwant Rai Mittal  1 , Anish Bhattacharya  1
Affiliations

Early Quantification of Salivary Gland Function after Radioiodine Therapy

Karan Singh Tanwar et al. Indian J Nucl Med. 2021 Jan-Mar.

Abstract

Purpose of the study: Radioiodine (I-131) is used as an effective noninvasive treatment for thyroid malignancies. Salivary gland is one of the most affected nontarget organs. The present study aims to perform early quantification of salivary gland function after I-131 therapy (RIT) for thyroid cancer considering I-131 down-scatter in the Tc-99m window.

Materials and methods: A total of 20 patients (6 males and 14 females) with differentiated thyroid carcinoma were enrolled in the study. Baseline dynamic salivary scintigraphy was performed in all patients using 185-370 MBq (5-10 mCi) Tc-99m pertechnetate. Posttherapy, salivary scintigraphy was performed 10-25 days after RIT in the range of 1.85-7.4 GBq (50-200 mCi). Time-activity curves obtained from the pre- and posttherapy dynamic salivary scintigraphy were used for semi-quantitative analysis. Uptake ratio (UR), ejection fraction (EF%), and maximum accumulation (MA%) were calculated by drawing regions of interest of individual parotid and submandibular glands over a composite image, after correcting for down-scatter from I-131 in the Tc-99m window. A paired t-test was used for comparison of the parameters obtained.

Results: Significant changes were observed in UR and EF% of both parotid and submandibular glands (P < 0.05). No significant changes were found in the value of MA% of left parotid gland and both submandibular glands in the posttherapy scans in comparison to pretherapy scans (P > 0.05). However, significant difference was observed in the MA% of the right parotid gland (P = 0.025).

Conclusion: Salivary gland function was found to deteriorate after RIT, with the parotid glands affected more than the submandibular glands.

Keywords: Radioiodine scatter; radioiodine therapy; salivary gland; salivary scintigraphy; thyroid carcinoma.

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Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
(a) Regions of interest on the summation image obtained by dynamic salivary scintigraphy, (b) schematic presentation of a time–activity curve in a normal pattern of salivary gland scintigraphy
Figure 2
Figure 2
(a) Posttherapy static image showing I-131 down-scatter counts in Tc-99m window before dynamic salivary scintigraphy, (b) posttherapy static image showing Tc-99m with I-131 down-scatter counts after dynamic salivary scintigraphy
Figure 3
Figure 3
(a) Salivary scintigraphy serial dynamic images before and (c) after I-131 treatment, (b) time–activity curves of parotid glands in pretherapy, and (d) posttherapy salivary scintigraphy
Figure 4
Figure 4
Bar graphs showing uptake ratio scintigraphy parameter for (a) right parotid, (b) left parotid, (c) right submandibular, and (d) left submandibular gland
Figure 5
Figure 5
Bar graphs showing maximum accumulation scintigraphy parameter for (a) right parotid, (b) left parotid, (c) right submandibular, and (d) left submandibular gland
Figure 6
Figure 6
Bar graphs showing ejection fraction scintigraphy parameter for (a) right parotid, (b) left parotid, (c) right submandibular, and (d) left submandibular gland
See this image and copyright information in PMC

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