[MR studies of extension and spread pattern of nasopharyngeal carcinoma]

Seven patients with T2-T4 nasopharyngeal carcinoma were examined by MRI on a 0.5T superconducting system. The obtained MRI images were reviewed focusing on the signal intensity (SI) of tumors, and the extension of tumors into the related spaces from the pharyngeal mucosal space (PMS). Consequently, the SI of tumors demonstrated low on T1 weighted images and high on T2 weighted images. The parapharyngeal space was the first space where the tumors extended from the pharyngeal mucosa. The parapharyngeal space was an intermediate point of extension to the masticator space (MS), the carotid space (CS), the retropharyngeal space (RPS), and the prevertebral space (PVS). The PVS involvement by tumors was not a direct extension from the PMS, because the posterior portion of pharyngobasilar fascia worked as a barrier on MR. Therefore, the longus capitus muscle in the prevertebral space was considered to be involved via the parapharyngeal space (PPS). The masticator space involvement was indicated by slightly high SI of pterygoid muscle on T2 weighted images, and also the effacement of the PPS fat and parapharyngeal venous plexus were considered as a sign of involvement into the masticator space. The retropharyngeal lateral lymph node (Rouviere) metastases were recognized by MR. These metastasized lymph nodes were low on T1 weighted images and high on T2 weighted images.