Parotid gland tumors: Preliminary data for the value of FDG PET/CT diagnostic parameters

OBJECTIVE. The purpose of this article is to establish ¹⁸F-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.