Diagnostic ability of [18F]-fluorodeoxyglucose-positron emission tomography/computed tomography for retropharyngeal lymph node in patients with oral cancer

Objective The first aim of this study was to evaluate the diagnostic ability of [18F]-fluorodeoxyglucose-PET/computed tomography (FDG-PET/CT) for retropharyngeal lymph node (RPLN) metastasis in patients with oral cancer. The second was to compare this with those of CT and MRI. Methods Among patients examined by both FDG-PET/CT and morphological imaging such as CT and MRI within 1 month, 42 patients (24 males and 18 females, mean age: 63.5 years; age range: 26-94 years) with a final diagnosis of retropharyngeal lymph node were included in this study. The diagnostic abilities for RPLN metastasis were evaluated by maximum standardized uptake value on PET/CT images and short axis diameter on morphological images. Optimal cut-off values for the nodal diagnoses of these modalities were obtained by receiver operating characteristic (ROC) analysis. Results In the ROC analysis, PET/CT had the largest area under the curve (AUC = 0.903), and diagnostic ability was superior to morphological images such as CT (0.678) and MRI (0.707). Using a maximum standardized uptake value of 3.5 as the cut-off value, sensitivity of 83.3%, specificity of 100% and accuracy of 95.2% were obtained. Conclusion The diagnostic ability of FDG-PET/CT for RPLN metastasis was superior to CT and MRI. FDG-PET/CT is considered a useful tool for the diagnosis of RPLN in patients with oral cancer.