Can Axial-Based Nodal Size Criteria Be Used in Other Imaging Planes to Accurately Determine “Enlarged” Head and Neck Lymph Nodes?

Objective. We evaluate if axial-based lymph node size criteria can be applied to coronal and sagittal planes. Methods. Fifty pretreatment computed tomographic (CT) neck exams were evaluated in patients with head and neck squamous cell carcinoma (SCCa) and neck lymphadenopathy. Axial-based size criteria were applied to all 3 imaging planes, measured, and classified as “enlarged” if equal to or exceeding size criteria. Results. 222 lymph nodes were “enlarged” in one imaging plane; however, 53.2% (118/222) of these were “enlarged” in all 3 planes. Classification concordance between axial versus coronal/sagittal planes was poor (kappa？=？？0.09 and ？0.07, resp., ). The McNemar test showed systematic misclassification when comparing axial versus coronal ( ) and axial versus sagittal ( ) planes. Conclusion. Classification of “enlarged” lymph nodes differs between axial versus coronal/sagittal imaging planes when axial-based nodal size criteria are applied independently to all three imaging planes, and exclusively used without other morphologic nodal data. 1. Introduction Detection and classification of metastatic lymphadenopathy in patients with mucosal squamous cell carcinoma (SCCa) of the head and neck are based upon careful evaluation of known patterns of nodal metastasis, anatomic nodal level boundaries, and nodal morphology [1–5]. Within the untreated neck, identification of nodal boundaries is highly reproducible and accurate and allows for proper communication of findings to the clinical services [1]. The evaluation of nodal morphology is more complex and requires a judicious application of multiple guidelines defining nodal size, shape, and density/signal intensity [2–5]. Additionally, it is important to define the relationship of a lymph node to the adjacent soft tissues, to other lymph nodes and to the expected patterns of nodal drainage and metastatic spread within the neck [2–5]. Unfortunately, even a careful review of the neck by computed tomography (CT) or magnetic resonance imaging (MRI) may yield a false negative rate of 15–20% [4] in detection of metastatic lymph nodes and is not reliable to detect regional occult nodal metastasis [5]. Nodal size is one of the most important morphologic features to detect metastatic nodal disease from a mucosal-based SCCa within the head and neck. Measurement guidelines for lymph nodes in the head and neck can be controversial [4, 6]. In our institution, lymph node measurements are performed along the long axis of the lymph node within the axial plane, according to criteria defined by Som [2]. Defining a lymph