Magnetic resonance imaging evaluation of extracranial head and neck tumors.

The introduction first of computed tomography (CT) and then in the 1980s of magnetic resonance imaging (MRI) has resulted in numerous applications of these imaging methods to head and neck oncology. MR imaging is a rapidly evolving field, which is replacing CT in the majority of lesions of the extracranial head and neck: tumors of the skull base, paranasal sinuses, nasopharynx, parapharyngeal space, and carcinomas of the oral cavity, pharynx, and larynx. MR imaging is the method of choice for the detection and staging of skull base lesions because of its superior sensitivity in detecting small lesions and its superior accuracy in staging the lesion and narrowing the diagnostic possibilities. MRI shows the extent of tumor in the paranasal sinuses more precisely, and by multiplanar imaging it outlines intracranial extension. MR imaging has greater accuracy than CT in differentiating parapharyngeal lesions and can detail the extent of tumor tissue in squamous cell carcinoma of the oral cavity, pharynx, and the larynx more accurately. It is more sensitive than CT in showing invasion by tumor tissue into the mandible or laryngeal cartilages.