Accuracy of PET Imaging and Ultrasonography for Preoperative Staging of Cervical Lymph Node Status in Oral Squamous Cell Carcinoma

Purpose: Cervical lymph node status is the strongest prognostic factor in oral squamous cell carcinoma (OSCC). While 18F-FDG-PET and cervical ultrasonography are widely used for preoperative staging, their diagnostic accuracy remains limited for small or equivocal nodes. This study compared both modalities against histopathology on a per-level basis and examined correlations of SUVmax and RECIST values with metastatic involvement. Methods: This retrospective single-centre study included patients with histologically confirmed OSCC who underwent preoperative 18F-FDG-PET and cervical ultrasonography, followed by resection and neck dissection (October 2018–December 2024). Imaging was interpreted independently and blinded to clinical and histopathological data. Histopathology served as the reference standard. Diagnostic accuracy was assessed on a level-by-level basis. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated and compared using McNemar’s test and logistic regression. Results: Among 100 patients (mean age 63.5 ± 10.6 years; 54% male, 46% female), the lateral tongue was the most frequent site (44%), and 31% showed nodal involvement on PET imaging. PET imaging yielded 59% sensitivity, 87% specificity, and 77% accuracy; ultrasonography achieved higher sensitivity (76%) but lower specificity (67%). Combined assessment improved sensitivity (78%) and NPV (82%) but reduced specificity. PET imaging was more specific, while ultrasonography was more sensitive. SUVmax and RECIST values were higher in metastatic nodes and independently predicted metastasis, though with substantial overlap and no reliable cut-off. Conclusions: PET imaging offers higher specificity, whereas ultrasonography provides greater sensitivity. Their complementary performance supports a multimodal approach to cervical staging in OSCC. Neither SUVmax nor RECIST values reliably distinguished benign from malignant lymph nodes.