The jugular foramen: a review of anatomy, masses, and imaging characteristics.

A variety of lesions may occur in the jugular foramen, arising from the structures normally found within the jugular foramen or from contiguous structures. The most common jugular foramen lesions are nontumoral pseudolesions (eg, asymmetrically enlarged jugular foramen, high or protruding jugular bulb) and tumors (eg, paraganglioma, metastasis). In nontumoral pseudolesions, computed tomography (CT) demonstrates smooth, intact margins of the jugular foramen. Turbulent or slow flow in a high or protruding jugular bulb can result in loss of the flow void and contrast enhancement at magnetic resonance (MR) imaging, thereby mimicking real disease. Use of flow-sensitive techniques or MR angiography will help clarify confusing cases. In cerebral venous thrombosis, CT findings are often normal. At conventional MR imaging, flow-related enhancement and in-plane, turbulent, or slow flow can cause loss of the flow void and thus mimic thrombosis. Consequently, phase-contrast MR venography is the imaging modality of choice in the assessment of cerebral venous thrombosis. Most tumoral lesions of the jugular foramen manifest at CT as areas of infiltrative bone destruction, although schwannoma and meningioma cause smooth enlargement of the jugular foramen. In addition, most of these tumors have low to intermediate signal intensity on T1-weighted MR images and intermediate to high signal intensity on T2-weighted MR images and enhance strongly after the administration of contrast material. Careful analysis of these imaging features and correlation with clinical manifestations can allow a more specific diagnosis.