Salivary gland dynamic imaging combined with tomosynthesis fusion imaging for evaluating postoperative salivary gland function changes in patients with differentiated thyroid cancer undergoing initial ¹³¹I therapy

Background: ¹³¹I therapy is a targeted therapy for patients with differentiated thyroid cancer (DTC) after surgery, reducing the risk of tumor recurrence and metastasis. Radioactive iodine can accumulate in the salivary glands, causing radiation damage. Dynamic imaging of the salivary glands can objectively assess the morphology and function of the salivary glands, making it a simple and non-invasive diagnostic method. The purpose of this study was to quantitatively analyze salivary gland function changes in patients with DTC undergoing postoperative 131I therapy using salivary gland dynamic imaging combined with tomographic fusion imaging.

Methods: A retrospective study enrolled 49 patients with DTC who underwent total thyroidectomy and received initial 131I therapy (dose: 5.55 GBq) between May 2020 and March 2024. Salivary gland dynamic imaging was performed on the day before ¹³¹I therapy and at least 4 months post-therapy. Salivary gland dynamic imaging was performed to measure the concentration index (CI), secretion index (SI), maximum standardized uptake value (SUVmax) of bilateral salivary glands, as well as SUVmax in the temporal region. The CI, SI, and the relative SUVmax (rSUVmax) in bilateral salivary glands to the temporal region were used as evaluation indicators.

Results: There were no statistically significant differences in the CI or SI of bilateral salivary glands before and after ¹³¹I therapy (P>0.05). The rSUVmax of parotid gland to temporal region showed a statistically significant difference before and after 131I therapy (P<0.05), whereas the rSUVmax of submandibular gland to temporal region showed no statistically significant difference (P>0.05).

Conclusions: In patients with DTC undergoing postoperative treatment, administering 131I therapy at an initial dose of 5.55 GBq with acid stimulation in the early phase can impair parotid gland function. Quantitative analysis using salivary gland dynamic imaging combined with tomographic fusion imaging enables accurate assessment of salivary gland function.