jugular foramen: a review of old and new imaging techniques and diagnoses

ABSTRACT

The imaging anatomy of the jugular foramen [JF] has been described. This is followed by an account of the various historical techniques used for diagnostic visualization. It is obvious that imaging interest has swung almost entirely to newer modalities as a result of dissatisfaction with plain films and conventional tomograms. In many parts of the world, places where no imaging facilities are available, a base view 50-70 degrees short of full extension, and a lateral oblique view are still of value in diagnosing a large foramen or fossa. Demonstration of the exact anatomic details of the bone is not possible without high resolution computed tomography [HRCT]. Conventional pleuridirectional tomography has retreated but remained complementary to computed tomography and a valuable tool in its absence. Computed tomography [CT] and magnetic resonance [MR] provide more information on intracranial or extracranial extensions of tumours as well as on the involvement of adjacent soft tissues. Four-vessel arteriography and jugular venography add important diagnostic characterization. The diagnostic criteria for each of the pathological conditions and the size of the lesion has been described with the justification for the use of a particular techniques. In nontumoral conditions, CT demonstrates smooth intact margin of the JF, except in cerebral venous thrombosis where phase contrast MR venography is the imaging modality of choice. In most tumoral lesions CT shows areas of infiltrative bone involvement, most schwannomas and meningiomas cause smooth enlargement rather than erosion. The multiplanner nature of MR imaging gives better definition and extent of soft tissues lesions, as well as more specific diagnostic criteria. Most of the tumors show low to intermediate signal intensity on T1- weighted images, and intermediate to high intensity on T2-weighted images, and enhance strongly. Each lesion requires a combination of available modalities to reach the specific diagnosis, sometimes the use of three dimentional CT is indicated, particularly in pre- and postsurgical intervention