Diagnostic accuracy and histopathologic findings of PET for cervical lymph node metastasis

FDG-PET is a useful diagnostic technique in the head and neck region; however, little is known about threshold standardized uptake values (SUV) and there are no definite diagnostic criteria. The purpose of this study was to determine the appropriate threshold SUV by comparing FDG accumulation with MRI and histopathological findings and to establish diagnostic criteria for cervical lymph node metastasis. We evaluated the uptake and measured SUV values of 54 metastatic lymph nodes on FDG-PET images in 12 patients with head and neck squamous cell carcinoma. Size and enhancement patterns were evaluated on MR imaging. We also assessed invasion of the resected lymph nodes. PET had a sensitivity of 72.2 %, a specificity of 98.6 % and an accuracy of 96.1 % at a threshold SUV of 2.5, based on the pathological diagnosis. For small nodes (< 10 mm), sensitivity was 57.6 %. Lymph nodes with FDG accumulation showed a wide range of histopathological invasion.