Evaluation of parotid gland function in type 2 diabetes patients using diffusion-weighted imaging before and after acid stimulation

Purpose To investigate the performance of diffusion-weighted magnetic resonance imaging (DW-MRI) as a noninvasive tool for assessing parotid gland function in type 2 diabetes mellitus (T2DM) patients. Methods T2DM patients ( n = 40, male, age 40–60 years) and healthy controls ( n = 40) were examined. Salivary function was assessed using 1.5D echo-planar diffusion-weighted imaging. The examinations were performed before and every 3 min until 10 times after acid stimulation with a 500-mg vitamin C pill. The maximum apparent diffusion coefficient (ADC) in the parotid glands (pADCmax) and time to peak ADC in the parotid glands (pTmax) during stimulation were obtained. ADC values at every time point and the peak value of ADC were compared between the two groups and statistically analyzed. Results The ADC values in the parotid gland in the resting state in the patient group were slightly lower than those in the healthy controls ((1.02 ± 0.08) × 10 − 3 mm 2 /s vs. (1.11 ± 0.09) × 10 −3 mm 2 /s, p > 0.05). The ADCs in the healthy controls increased after stimulation until they gradually reached their peak. The ADCs in the patient group first decreased after stimulation and then gradually increased until they peaked. The pADCmax in the patient group was significantly lower than that in the healthy controls ((1.45 ± 0.08) × 10 −3 mm 2 /s vs. (1.7 ± 0.06) × 10 −3 mm 2 /s, p < 0.05). The peak ADCs in the parotid gland and relative signal intensity after acid stimulation were significantly correlated ( r = 0.666, p < 0.05). Conclusion DW-MRI before and after acid stimulation is potentially useful for noninvasive prediction of diabetes-induced xerostomia severity. ADC value is a sensitive indicator of parotid gland dysfunction and may indirectly reflect the degree of this dysfunction caused by fat deposition.