Radiological evaluation of paragangliomas of the head and neck.

Paragangliomas can be differentiated angiographically from most other tumors in the head and neck by their profuse vascularity; specific classification is based on their position and displacement of adjacent vessels. Subtraction usually aids in diagnosis. In most cases, bilateral carotid angiography should be performed, since the ipsilateral carotid artery may have to be ligated and an asymptomatic contralateral tumor may also be found during surgery. Studies of multiple vessels will often show an additional blood supply. Computed tomography can demonstrate the tumor's vascular nature and position and is valuable in follow-up after radiation therapy.