Intravoxel incoherent motion imaging measurement of perfusion changes in the parotid gland provoked by gustatory stimulation: A pilot study.

PURPOSE: To demonstrate the feasibility of intravoxel incoherent motion imaging (IVIM) for quantification of perfusion changes in the parotid gland after gustatory stimulation. MATERIALS AND METHODS: Eight healthy volunteers underwent diffusion-weighted magnetic resonance imaging (MRI) of the neck at 3T with 11 dynamic acquisitions (9 b-values between 0 and 980 s/mm2 , 2:40 min each). After 5:20 minutes, a lemon-mint-drop was administered orally. Perfusion fraction (Fp ), pseudodiffusion (D*), tissue diffusion (Dt ) coefficients, and optimal b-value threshold were measured using a multistep variable b-value threshold fitting approach. Dynamic changes in the coefficients between three exemplary timepoints (baseline, after stimulation, after dissolution) were compared using a Mann-Whitney U-test with Bonferroni correction (P < 0.016 significance level). RESULTS: Mean values (95% confidence interval [CI]) for IVIM parameters at baseline were Fp : 0.11 (0.08-0.15), D*: 56.48 mm2 /s (39.71-98.27), Dt : 1.01 mm2 /s (0.84-1.06), b-value threshold: 30 s/mm2 (21.25-105). After stimulation: Fp 0.16 (0.15-0.24; P < 0.01), D* 93.83 mm2 /s (77.98-129.53, P = 0.25), Dt 0.93 mm2 /s (0.87-1.08, P = 0.94), b-value threshold 20 s/mm2 (13.75-26.25 s/mm2 , P = 0.10), reflecting the increase in tissue perfusion. After dissolution of the drop: Fp : 0.13 (0.11-0.18, P = 0.38), D*: 101.61 mm2 /s (90.68-144.55, P = 0.07), Dt : 0.91 mm2 /s (0.85-1.05, P = 0.64), b-value threshold: 15 s/mm2 (11.25-40, P = 0.38). CONCLUSION: The IVIM method allows for simultaneous quantification of changes in perfusion and diffusion effects after gustatory stimulation of the parotid gland. LEVEL OF EVIDENCE: 2 J. Magn. Reson. Imaging 2017;45:570-578.