Objectives/Hypothesis: The aim was to compare the value of 18-Fluoro-Deoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) regarding contralateral lymph node (LN) metastasis in the neck. Study Design: Retrospective analysis of 61 patients staged by 18F-FDG-PET/CT. Methods: Cytology/histology served as a reference standard. Further, metabolic midline invasion (MI) of the primary tumor and the presence of bilateral LN metastases were assessed. Results: A true positive

more »

... rate in the ipsilateral neck of 80% versus 65% in the contralateral neck was found (P 5 0.067). Median-standardized uptake value (SUV)-max for suspicious LN ipsilaterally was 7.6 versus 5.8 contralaterally (P 5 0.038). There was no positive correlation between metabolic MI and bilateral metastasis (P 5 0.82). Conclusions: The rate of true positive detected LN by 18F-FDG-PET/CT is less on the contralateral neck side; therefore, all suspicious LNs should be verified by cytology. A high SUV in the contralateral neck suggests metastatic disease regardless of nodal size. Metabolic MI needs to be addressed carefully as it was not predictive for bilateral LN involvement.