Objective: The purpose of this article is to establish (18)F-FDG metabolic imaging parameters to differentiate benign and malignant tumors of the parotid gland.
Materials and methods: Forty-nine patients with increased FDG uptake in the parotid gland were selected for the study group (29 men and 20 women; mean age, 63.14 ± 12.32 years). Another 49 patients without head and neck malignancies were selected as the control group (24 men and 25 women; mean age, 65.80 ± 11.51 years); they did not have a parotid lesion or increased FDG uptake in the parotid gland. Maximum standardized uptake value (SUV(max)) was obtained for all patients. Metabolic tumor volume and total glycolytic activity were measured in patients with a discrete parotid lesion (n = 24). Nonparameteric Student t test (Mann-Whitney U test) was performed for between-group analysis.
Results: The median SUV(max) of the increased diffuse uptake (2.55; interquartile range [IQR], 1.03-4.07) was significantly lower than the median SUV(max) of tumors (8.48; IQR, 1.46-15.5) (p < 0.01). The median SUV(max) of malignant tumors (11.8; IQR, 4.45-19.15) was significantly (p < 0.05) higher than that of benign tumors (6.4; IQR, 3.4-9.0). There was significant difference (p = 0.003) in the median metabolic tumor volume for malignant tumors (8.9; IQR, 5.1-25.5) and benign tumors or lesions (1.4; IQR, 1.00-2.9). Similar results were found for total glycolytic activity for malignant tumors (67.9; IQR, 24.2-137.6) and benign tumors or lesions (8.4; IQR, 3.9-13.6) (p = 0.002).
Conclusion: FDG PET/CT SUV(max), metabolic tumor volume, and total glycolytic activity are imaging parameters to differentiate benign and malignant tumors of the parotid gland.