Value of apparent diffusion coefficient calculation before and after gustatory stimulation in the diagnosis of acute or chronic parotitis

The purpose of the study was to investigate the value of diffusion-weighted (DW) echo-planar imaging (EPI) for quantifying physiological changes of the parotid gland before and after gustatory stimulation in patients suffering from acute or chronic recurrent inflammation in comparison with healthy volunteers. Using a DW-EPI sequence at 1.5 T, parotid glands of 19 consecutive patients with acute (n = 14) and chronic (n = 5) inflammation of parotid glands and 52 healthy volunteers were examined. Magnetic-resonance (MR) images were obtained before and after gustatory stimulation with 5 cc of lemon juice. In volunteers mean ADC values of 1.14 × 10⁻³ mm²/s before and 1.2 × 10⁻³ mm²/s after gustatory stimulation were observed. In acute inflammation ADC values were higher before [1.22 × 10⁻³ mm²/s (p = 0.006)] and after stimulation [1.32 × 10⁻³ mm²/s (p < 0.001)]. Before stimulation ADC differences between chronic inflammation (1.05 × 10⁻³ mm²/s) and healthy volunteers (p = 0.04) as well as between acute and chronic inflammation (p = 0.005) were statistically significant. No differences were detected after stimulation between chronic inflammation (1.2 × 10⁻³ mm²/s) and healthy volunteers (p = 0.94) and between acute and chronic inflammation (p = 0.15), respectively. DW-EPI seems to display the physiological changes of the parotid gland in patients suffering from acute or chronic inflammation and might be useful for discriminating healthy from affected glands.