Purpose: To assess the efficacy of diffusion-weighted (DW) MR imaging for differentiating between Warthin's tumor and oncocytoma of the parotid gland.
Methods: Forty-five histopathologically confirmed parotid gland tumors (41 Warthin's tumors and 4 oncocytomas) were examined by MR imaging including DW imaging. 18F-fluorodeoxyglucose PET/CT was also performed in 9 Warthin's tumors and 3 oncocytomas. We retrospectively reviewed the images and compared the MR signal intensities, apparent diffusion coefficients (ADCs), and maximum standardized uptake values (SUVmax) of the solid components between the two pathologies.
Results: The signal intensity ratios (SIRs) on both T2-weighted images (0.92 ± 0.18 vs 0.65 ± 0.13, p < 0.01) and DW images (1.24 ± 0.42 vs 0.43 ± 0.16, p < 0.001) were higher in Warthin's tumors than in oncocytomas. ADCs (0.79 ± 0.11 vs 1.06 ± 0.06 × 10-3 mm2/s, p < 0.001) were lower in Warthin's tumors than in oncocytomas. No significant differences in the SIRs on T1-weighted images (1.09 ± 0.12 vs. 0.99 ± 0.07, p = 0.051) and SUVmax (8.22 ± 3.86 vs. 8.11 ± 1.33, p = 0.864) were found between Warthin's tumor and oncocytoma.
Conclusion: DW imaging with ADC measurements is useful for the differentiation of Warthin's tumor from oncocytoma of the parotid gland.
Keywords: Diffusion-weighted imaging; Oncocytoma; Parotid gland; Warthin’s tumor.