F-18-2-fluoro-2-deoxyglucose (FDG) is widely used tracer in PET imaging, and it allows to observe the metabolic increase in tumor cells. Recently, combined PET and CT is used to identify the anatomic structures additional to the metabolic data. This FDG-PET/CT is one of the useful methods for determination of the TNM staging before the treatment, setup of the treatment plan, and the evaluation of the recurrence of the tumor after the treatment in the cancer patients. Also it can be used for the evaluation of the metastatic tumor and distant metastasis, not like the clinical examination, CT, or MRI. Because of its high sensitivity and specificity, it is useful for evaluation of the metastasis of neck node. However FDG-PET/CT may give a rise for confuse in evaluation of tumor, because increased uptake in FDG-PET/CT could be observed in the area that received invasive procedure or is inflammatory. The study on the false positive lymph nodes is necessary, because false positive lymph nodes can result in wider neck dissection.

This study was performed to find criteria of positive/false positive lymph node in FDG-PET/CT by evaluating the false positive lymph nodes and factors related to tumor or inflammation.

Conflict of interest: None declared.