CT and MR Findings in Head and Neck Cancer
Cross-sectional imaging has revolutionized staging and treatment planning of head and neck malignancies. Both CT and MRI are able to depict pathology and provide valuable information allowing for tissue characterization and better discrimination among various pathologic entities, thus facilitating differential diagnosis. Exquisite anatomic details provided by cross-sectional imaging facilitate assessment of disease extension and staging, resulting in better patient management. In particular, MRI is considered the modality of choice for the evaluation of nasopharyngeal, sinonasal, and parotid tumors, while tumors of the oropharynx, larynx, and hypopharynx are initially assessed with CT. The initial step when evaluating a neck lesion is to determine the space where the lesion originates, since specific lesions are being found within each separate anatomic space. This is markedly limiting the differential diagnosis. Additionally, lymph node status is an important prognostic factor, and in cross-sectional imaging, its evaluation mainly relies on size criteria, while the presence of central necrosis is also an important feature. In case of laryngeal carcinoma, the role of cross-sectional imaging is to evaluate tumor extent, while it contributes to treatment planning and patient follow-up. Finally, in many head and neck regions, such as sinuses, nasopharynx, skull base, oral cavity, and hypopharynx-larynx, CT and MR imaging have complementary roles.