Monitoring of Gustatory Stimulation of Salivary Glands by Diffusion-Weighted MR Imaging: Comparison of 1.5T and 3T

BACKGROUND AND PURPOSE: Our aim was to compare different field strengths monitoring physiologic changes due to oral stimulation of parotid glands by using diffusion-weighted (DW) echo-planar imaging (EPI). MATERIALS AND METHODS: Twenty-seven healthy volunteers were examined with a DW-EPI sequence at 1.5T and 3T before and after oral stimulation with commercially available lemon juice. The b factors used were 0, 500, and 1000 s/mm 2 . Apparent diffusion coefficient (ADC) maps were evaluated with a manually placed region of interest including the entire parotid gland. For comparison of results, a Student t test was used on the basis of the mean of the volunteer median values. To compare both field strengths, we calculated the Pearson correlation coefficient ( r ). RESULTS: DW-EPI MR imaging visualized the parotid glands of all volunteers. With 1.5T, the mean ADC before stimulation was 1.12 × 10 −3 mm 2 /s ± 0.08 × 10 −3 mm 2 /s. After stimulation with lemon juice, the ADC increased to 1.18 × 10 −3 mm 2 /s ± 0.09 × 10 −3 mm 2 /s. For 3T, the ADC before stimulation was 1.14 × 10 −3 mm 2 /s ± 0.04 × 10 −3 mm 2 /s, with an increase to 1.17 × 10 −3 mm 2 /s ± 0.05 × 10 −3 mm 2 /s after stimulation. For both field strengths, the increase in ADC after stimulation was significant ( P r = 0.955, and 0.936, respectively). CONCLUSION: DW-EPI MR imaging allows monitoring of physiologic changes due to oral stimulation of parotid glands by using DW imaging with high correlation between 1.5T and 3T.