To evaluate the value of shear wave elasto-graphy (SWE) in salivary gland injuries after postoperative radioactive iodine (RAI) therapy for papillary thyroid carcinoma (PTC).

From August 24, 2021, to January 17, 2022, a total of 113 PTC patients who underwent RAI treatment after surgery from the Department of Endocrinology, the First Affiliated Hospital of Shandong First Medical University (Shandong Qianfoshan Hospital) and 87 healthy controls were retrospectively recruited. PTC group was divided into single RAI treatment group (n=36) and multiple RAI treatment group (n=77). Two-dimensional ultrasound and SWE examination results of parotid gland and submandibular gland were collected, including parotid gland thickness, submandibular gland volume and mean shear wave velocity (SWV) of the left and right. Student′s t-test was used to compare the differences between the 2 groups.

The volumes of the left submandibular gland in the PTC group and the control group were (7.55±0.64)cm³ and (8.31±0.41)cm^3, respectively. The volumes of the right submandibular gland were (7.55±0.47)cm³ and (8.29±0.24)cm^3, respectively. The thicknesses of the left parotid gland were (17.50±0.51)mm and (18.06±0.38)mm, respectively. The thicknesses of the the right parotid gland were (17.48±0.52)mm and (18.08±0.33)mm, respectively. Compared to the control group, both the volumes of the left and right submandibular glands in the PTC group showed a significant decrease (t=9.65, 13.40, all P<0.05), and the thicknesses of the left and right parotid glands also significantly decreased (t=8.57, 9.40, all P<0.05). The SWV of the left submandibular gland in the PTC group and the control group were (2.23±0.22)m/s and (1.93±0.15)m/s, respectively.Similarly, the SWV of the right submandibular gland were (2.22±0.21)m/s and (1.90±0.13)m/s, respectively. The SWV of the left parotid gland were (2.21±0.23)m/s and (1.86±0.14)m/s, respectively. The SWV of right parotid gland were (2.29±0.23)m/s and (1.90±0.15)m/s, respectively.The SWV of both left and right submandibular glands and parotid glands in the PTC group were significantly higher than those in the control group (t=10.91, 12.49, 12.52, 13.72, all P<0.05). There were no significant differences in parotid gland thickness, submandibular gland volume, SWV of parotid gland and submandibular gland between single RAI treatment group and multiple RAI treatment group (all P>0.05).

For patients after RAI treatment, SWE may be a simple, non-invasive method to evaluate parotid and submandibular gland damage by assessing salivary gland hardness.