The role of positron emission tomography in the evaluation of the N-positive neck

BACKGROUND: A major prognostic indicator in patients with squamous cell carcinoma of the upper aerodigestive tract is the presence or absence of cervical metastasis. Nodal involvement at different levels affects treatment. Thus identification of the degree of nodal involvement is important. Evaluation of the neck by conventional imaging modalities (computed tomography or magnetic resonance imaging) is not completely accurate. Positron emission tomography (PET) scanning as a dynamic functional assessment may allow detection of multiple metastatic nodes at different levels. PURPOSE: We sought to compare the effectiveness of PET with pathologic examination for: presence, location, and number of cervical metastases in the clinically N-positive neck. SETTING: Tertiary care academic facility. MATERIALS AND METHODS: From 1994 to 1997, 15 patients with clinically N-positive necks who had preoperative PET scans underwent 23 neck dissections. PET scans were correlated with the pathologic findings of the neck dissections in determining the ability to correctly identify the number and level(s) of nodal disease. RESULTS: When determining identification of the level of disease, PET demonstrated sensitivity of 81%; specificity, 99%; positive predictive value, 97%; negative predictive value, 90%; and accuracy, 92%. When evaluating the ability to correctly predict neck stage, PET demonstrated sensitivity of 86%, positive predictive value of 100%, and accuracy of 80% compared with clinical examination with sensitivity of 53% and accuracy of 53%. CONCLUSION: PET accurately identified disease in the N-positive neck. Its ability to identity multiple level disease may allow it to help predict the selectivity of neck dissection in the therapeutic protocol.