Retrospective review: usefulness of a number of imaging modalities including CT, MRI, technetium-99m pertechnetate scintigraphy, gallium-67 scintigraphy and F-18-FDG PET in the differentiation of benign from malignant parotid masses.

Objective: The aim of this study is to evaluate an imaging approach using computed tomography (CT), magnetic resonance imaging (MRI), technetium-99m pertechnetate scintigraphy (99mTc pertechnetate scintigraphy), gallium-67 scintigraphy (67Ga scintigraphy) and fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET).

Methods: We reviewed retrospectively 59 patients with parotid masses. CT, MRI, 67Ga scintigraphy, 99mTc pertechnetate scintigraphy, and 18F-FDG PET were performed.

Results: All of the benign tumors had smooth margins on CT and MRI. Patients with inflammatory lesions and malignant lesions showed well-defined margins or ill-defined margins. All Warthin's tumors showed high technetium accumulation. Many of malignant tumors showed high FDG accumulation. Both pleomorphic adenomas and Warthin's tumors showed high accumulation in some cases on 18F-FDG PET. Among 15 patients with pleomorphic adenoma, 14 patients showed marked hyperintensity relative to CSF on T2-weighted images and partial enhancement on contrast-enhanced T1-weighted images. Combination of several imaging modarity offered usefulness of differential diagnosis for parotid masses.

Conclusions: An efficient combination of imaging methods may be helpful for achieve the correct diagnosis.