Computed Tomography Features of the Major Salivary Glands After Radioactive Iodine Ablation in Patients with Papillary Thyroid Carcinoma

Objective: No previous study has investigated computed tomography (CT) features of the major salivary glands (MSGs) after postoperative radioactive iodine ablation (RIA). This study aimed to assess CT features of the MSGs after RIA in patients with papillary thyroid carcinoma (PTC).

Methods: The study population comprised consecutively registered PTC patients who had undergone total thyroidectomy, RIA, follow-up neck ultrasonography (US), and neck CT. The US and CT features of the parotid and submandibular glands in each patient were retrospectively evaluated by a single radiologist. Post-RIA changes were determined by comparisons between follow-up neck US results (main reference) and between preoperative and post-RIA neck CT features.

Results: Of the 28 patients, 13 (46.4%) showed post-RIA changes in the parotid glands (n = 8), submandibular glands (n = 0), or both (n = 5) on neck CT. Of the 56 MSGs in 28 patients, post-RIA changes were more common in the parotid glands (n = 23, 41.1%) than in the submandibular glands (n = 8, 14.3%). The common CT findings of post-RIA changes in the parotid gland included low parenchymal attenuation, decreased glandular size, a lobulated margin, decreased or increased parenchymal enhancement, and an inhomogeneous enhancement pattern, whereas common CT findings of post-RIA changes in the submandibular gland included decreased glandular size, a lobulated margin, iso-enhancement, and an inhomogeneous enhancement pattern.

Conclusion: The common CT features of post-RIA changes in MSGs include decreased glandular size, a lobulated margin, and an inhomogeneous enhancement pattern.