Indeterminate Lymph Nodes Assessment in Oral Squamous Cell Carcinoma Using CT, MRI, and PET-CT: A Retrospective Study

Objective: This study aimed to evaluate and compare the diagnostic performance of computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT) in detecting metastatic cervical lymph nodes in patients with oral squamous cell carcinoma (OSCC), with a particular focus on radiologically indeterminate lymph nodes. Materials and Methods: A retrospective analysis was conducted on OSCC patients who underwent CT, MRI, and PET-CT imaging prior to surgery, followed by histopathologic confirmation. Lymph nodes were categorized as metastatic, indeterminate, or benign based on imaging criteria specific to each modality. Diagnostic accuracy, sensitivity, and specificity were calculated using histopathology as the reference standard. Results: After excluding lymph nodes classified as indeterminate on preoperative imaging, CT demonstrated an accuracy of 83.6%, sensitivity of 51.9%, and specificity of 92.4% for metastatic lymph node detection. MRI and PET-CT showed comparable accuracies (81.6% and 80.8%, respectively) and identical sensitivities (53.9%). In contrast, among radiologically indeterminate lymph nodes, most lesions identified on CT and MRI were histopathologically benign, whereas PET-CT yielded very few indeterminate nodes, all of which were benign. For benign node identification, PET-CT exhibited the highest sensitivity (86.8%) but lower specificity (55.8%), while CT and MRI demonstrated more balanced specificity (73.1%) with lower sensitivity. Logistic regression confirmed SUVmax as a significant predictor of malignancy (p < 0.001; odds ratio 1.71, 95% CI: 1.48-2.35), and ROC analysis demonstrated strong discriminative performance (AUC = 0.88), with an optimal SUVmax cutoff of 3.6. Conclusion: While CT remains highly specific, PET-CT offers greater sensitivity in detecting benign and indeterminate lymph nodes, making it a valuable adjunct in preoperative assessment. SUVmax serves as a strong quantitative indicator for metastatic involvement. A multimodal imaging approach may enhance diagnostic accuracy, particularly in cases where lymph nodes lack definitive radiologic features.