Is there an additive value of 18F-FDG PET-CT to CT/MRI for detecting nodal metastasis in oropharyngeal squamous cell carcinoma patients with palpably negative neck?

Background Cervical node metastasis is one of the most significant prognostic factors in patients with oropharyngeal squamous cell carcinoma (SCC). There is little information regarding the comparison of histopathologic analysis following neck dissection with imaging results in oropharyngeal SCC. Purpose To investigate the clinical utility of PET-CT compared with computed tomography (CT) or magnetic resonance imaging (MRI) for detecting nodal metastasis in oropharyngeal SCC patients with palpably negative neck and to investigate whether pretreatment imaging modalities support the rationale for elective neck treatment. Material and Methods A total of 49 oropharyngeal SCC patients with palpably negative neck (42 men, 7 women; average age, 59.1 years) underwent primary tumor resection and neck dissection as a primary treatment. All patients were preoperatively evaluated with PET-CT and CT/MRI, and the diagnostic accuracy of each imaging modality was assessed by comparison with histopathologic results of the surgical specimen. Results Twenty-five (51.0%) of our 49 patients had neck metastases. On a level-by-level analysis, the sensitivity of PET-CT, CT/MRI, and a combination of PET-CT and CT/MRI was 54.6%, 54.6%, and 60.6%, respectively, at all neck levels. The area under the ROC showed that the diagnostic performance of the combined interpretation was not significantly different from that of CT/MRI alone (0.780 vs. 0.750, respectively; P=0.158) and PET-CT alone (0.780 vs. 0.765, respectively; P=0.501). Conclusion Addition of PET-CT to CT/MRI did not provide better diagnostic accuracy for detecting nodal metastasis in preoperative evaluation of oropharyngeal SCC patients with palpably negative neck, suggesting that current imaging studies might not replace elective neck dissection.