A retrospective study of magnetic resonance sialography imaging applied in the prognostic evaluation of chronic obstructive parotitis.

Background: Magnetic resonance sialography (MRS) can be used to clearly examine the main duct of the parotid and is widely applied in the diagnosis of chronic obstructive parotitis (COP). However, there are few studies on the classification, treatment options and prognosis of COP using MRS. Methods: Clinical and imaging data were retrospectively collected from 41 patients with COP between January 2010 and December 2020 at the Ninth People's Hospital affiliated with Shanghai Jiao Tong University School of Medicine. All patients underwent MRS and were treated with intraductal irrigation. The patients were divided into 2 groups according to the presence or absence of symptomatic relapse during the 6-month follow-up period. The imaging features of parotid MRS included three parts: gland volume, stenosis classification and dilatation classification. The location/length of dilatation, the widest diameter of the dilated duct, and the condition of the branch ducts were also recorded and compared between the groups. Results: A mean of 14.8±12.3 irrigations were performed. There were 15 patients with recurrence and 26 without recurrence. There was no significant difference in the parotid volume (P=0.460), stenosis grade (P=0.738) or maximum diameter of dilatation of the branch duct (P=0.723) between the recurrence and non-recurrence groups. Statistically significant differences were found in dilatation classification (P=0.009), length of dilatation (P=0.043), condition of the branch ducts (P=0.017) and dexamethasone use (P=0.031). Conclusions: MRS is an available diagnostic and grading modality for COP. The imaging features and classification of the parotid main duct in MRS could be helpful for treatment selection. Patients who accept irrigation could be less likely to experience recurrence with a low dilatation grade and no branch duct dilatation.