Résumé
ObjectiveTo evaluate the function of the salivary glands with gustatory stimulation by using MR DWI.MethodsA prospective study was conducted in 30 patients with nasopharyngeal carcinoma who had normal salivary function.A DWI sequence was performed on the salivary glands at resting state,and continually repeated on the parotid immediately after oral ascorbic acid stimulation over a period of 21 minutes (once every 18 seconds).The multiple b-values (0,400,600,800,1000 s/mm2) were used.ADC maps were evaluated with a manually placed region of interest including the entire salivary gland.The ADC of each gland was obtained by taking the mean of values on three contiguous sections containing the largest areas of the gland.The paired two-tailed Student t test was used to compare the ADC values of the parotid and the submandibular glands at rest,and of the parotid before and after stimulation.ResultsThe mean ADC value at rest was significantly lower in the parotid [ (1.23 ±0.12) × 10-3 mm2/s] than in the submandibular glands [(1.34 ± 0.07 ) × 10 -3 mm2/s,t =4.545,P ＜ 0.01 ].After acid stimulation,the ADC value increased from the baseline to (1.41 ±0.19) × 10-3 mm2/s firstly and then fluctuated at the following time,with a peak value of ( 1.49 ± 0.20 )× 10 -3 mm2/s and the average value of ( 1.36 ±0.17) × 10-3 mm2/s.The average value was significantly different from the baseline value (t =15.127,t =11.905,P ＜ 0.01 ).The minimum value [ ( 1.24 ± 0.14) × 10-3 mm2/s] was not significantly different compared to the baseline value (t =1.329,P ＞ 0.05 ).ConclusionMR DW1 can noninvasively evaluate the physiologic changes of salivary glands before and after acid stimulation.