Diffusion-weighted MRI at the Late Stage after Radiotherapy for Evaluating Salivary Gland Injury.

Abstract

Salivary gland injury is the main complication of radiotherapy for nasopharyngeal carcinoma (NPC) patients. The purpose of this study was to evaluate the value of diffusion-weighted magnetic resonance imaging (DW-MRI) as a reliable tool to assess salivary gland function in NPC patients after radiotherapy. This study analysed the MR images of 31 NPC patients at different time points within 2-3 years after radiotherapy. The changes in the apparent diffusion coefficient (ADC) and its relationship with radiation dose were analysed. Both the parotid and submandibular gland ADC values increased significantly 3-6 months after radiotherapy and then decreased gradually. The ADC value of the parotid gland was positively correlated with radiation dose at the late stage (P = 0.012, r = 0.359). The submandibular gland ADC change value (P = 0.035) and change ratio (P = 0.027) of the high radiation dose group were significantly lower than those of the low dose group at the late stage. The correlation between ADC values of parotid and submandibular glands and the radiation dose indicated that DW-MRI could be helpful in evaluating salivary gland injury after radiotherapy.