[Study on DWMRI in evaluating the influence of intensity modulated radiotherapy on salivary gland function of nasopharyngeal carcinoma patients].

OBJECTIVE

To evaluate the dynamic change of salivary gland function in patients with nasopharyngeal carcinoma (NPC) before and after intensity modulated radiotherapy (IMRT) by DWMRI.

METHODS

Twenty-three NPC patients confirmed by pathology were enrolled. Male/Female: 19/4. The age was from 37 to 69 years. All cases underwent salivary glands examination by DWMRI before IMRT, at the end of IMRT, 6 months and 12 months after IMRT, at the same time the ADC value of salivary glands were calculated. The patients were divided into two groups: G1, Dmean < 26 Gy, G2, Dmean ≥ 26 Gy. SPSS 13.0 and SAS 8.2 software was used to analyze the date.

RESULTS

The ADC values of parotid in two group patients at rest were not significantly different between 6 months after and at the end of IMRT (t value was 0.732, 1.405, all P > 0.05). The ADC values of parotid in two group patients at rest were significantly lower in the 12 months after IMRT than at the end of IMRT (t value 2.621, 3.417, all P < 0.05). During the period of acid stimulation, A significant change of ADC in parotid was found in G1 (all P < 0.05) and no significant change of ADC in parotid was found in G2 at the various follow-up time after IMRT (all P > 0.05). At the various follow-up time after IMRT, the average ADC values of parotid were significantly higher in G2 than G1 in the same time points of acid stimulation (all P < 0.05). The ADC values of submandibular glands at rest were significantly higher at the various follow-up time after IMRT than before IMRT (t value was -9.782, -8.963, -7.722, all P < 0.05). During the period of acid stimulation no significant change of ADC in submandibular glands was found after IMRT (F = 1.124, P = -0.348).

CONCLUSIONS

The changes of salivary function can be well reflected by ADC values. There is a good clinical application value of DWMRI for evaluating radiation-induced salivary glands functional changes and observing salivary function recovery during the follow-up period after IMRT.