Sonographic Appearance of Parotid Glands in Patients Treated With Intensity-Modulated Radiotherapy or Conventional Radiotherapy for Nasopharyngeal Carcinoma

This study aimed to investigate and compare the sonographic appearances of parotid glands in nasopharyngeal carcinoma patients treated with conventional radiotherapy (RT) or intensity-modulated radiotherapy (IMRT), and to compare them with healthy subjects. Totally 43 patients treated with conventional RT, 38 patients treated with IMRT and 58 healthy subjects were recruited and underwent parotid ultrasonography. Parotid glands were assessed for their size, echogenicity and internal architectures. The mean transverse dimension of parotid glands in patients treated with conventional RT and those treated with IMRT were significantly smaller than that in healthy subjects (p < 0.05). Parotid glands of the IMRT group tended to be hyperechoic (93%), homogenous (62%), without hypoechoic areas (64%) and with marginally-seen intra-parotid ducts (89%), which are similar to those in healthy subjects. Parotid glands in the conventional RT group tended to be hypoechoic (51%), heterogeneous (98%), with hypoechoic areas (94%) and had obviously-seen intra-parotid ducts (64%). For accurate diagnosis, post-RT changes of parotid glands should be noted in ultrasound examination of patients with previous radiotherapy.