Diagnostic Value of Neck Node Status Using 18F-FDG PET for Salivary Duct Carcinoma of the Major Salivary Glands

18F-FDG PET and PET/CT have shown clinical usefulness in the initial staging and follow-up of patients with salivary malignancy. Therefore, we evaluated the utility of 18F-FDG PET in preoperative staging, determining the extent of neck node involvement, and surgical planning for patients with salivary duct carcinoma (SDC) of the major salivary gland. Methods: We evaluated 18 patients with SDC who were assessed by 18F-FDG PET and CT before surgery. The sensitivity, specificity, accuracy, and predictive values of CT and PET/CT for predicting the primary tumor site and determining the extent of neck node involvement at each dissected neck level were evaluated by comparing imaging findings with pathologic nodal stage. Results: The median maximum standardized uptake value of the primary lesions and cervical nodes were 4.7 (range, 1.8–12.1) and 5.8 (range, 1.7–13.0), respectively. The sensitivities of 18F-FDG PET and CT for predicting the primary tumor site were 100% (18/18) and 94.4% (17/18), respectively. In analyzing cervical lymph nodes at 73 dissected neck levels, 18F-FDG PET had a sensitivity of 76.1%, a specificity of 96.3%, a positive predictive value of 97.2%, and a negative predictive value of 70.3%; the corresponding values for CT were 39.1%, 92.6%, 90.0%, and 47.2%, respectively. The sensitivity and negative predictive value were significantly higher for 18F-FDG PET than for CT (P < 0.001 and P = 0.03, respectively).18F-FDG PET determination of the extent of neck node involvement changed the neck dissection regimen in 5 patients (27.8%). Conclusion: SDC of the major salivary gland is a highly metabolic tumor with high 18F-FDG uptake. 18F-FDG PET is useful for evaluating neck node status and for determining surgical planning in patients with major salivary gland SDC.