Detection of metastasis in cervical lymph nodes: CT and MR criteria and differential diagnosis.

Radiologists are frequently asked to evaluate cervical lymph nodes with CT or MR imaging to determine if metastases are present, how extensive the metastases are, and if they have spread from lymph nodes to critical adjacent structures such as the carotid artery and skull base. Accurate information of this type is essential if the most appropriate treatment is to be selected. The purpose of this report is to review the diagnostic criteria that are currently used with CT and MR imaging to diagnose metastases in cervical nodes by evaluating nodal size, shape, grouping, and necrosis and extranodal tumor spread. In addition, emphasis is placed on details that should be included in the CT and MR report, such as the location of the nodes, the presence of nodal calcification, and the presence of associated diseases such as parotid cysts that may suggest a specific diagnosis like HIV infection. Because optimal treatment planning depends on the combined information gleaned from the clinical evaluation and the imaging studies, it is essential that there be a close dialogue between clinicians and radiologists.