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Three dimensional computed tomography angiography in imaging jugular foramen lesions.

There are multiple entities in the differential diagnosis of jugular foramen lesions. These often arise from structures normally located within the jugular foramen, including neurofibromas and schwannomas of the cranial nerves, pseudolesions of the jugular bulb, such as high or protruding variants, arteriovenous malformation or jugular vein thrombosis, and paragangliomas arising along the adventitia of the jugular vein or alongArnold and Jacobson nerves (1). In addition, a wide spectrum of lesions may originate from contiguous structures and impinge on the jugular foramen (for a review, see Caldemeyer et al. (1)). Careful analysis of the imaging characteristics of these lesions and correlation with the clinical presentation are essential for the diagnosis. The most commonly used diagnostic imaging techniques are computed tomography (CT) and magnetic resonance (MR) imaging, which provide essential information regarding the size, growth pattern, and location of themass. Unenhanced or contrast-enhanced CT andMR imaging are routinely used for the evaluation of lesions in this location. CT with multiplanar reformations demonstrates the bone anatomy optimally, whereas MR reveals the vascular and soft tissue structures to best advantage (2). However, a high or protruding jugular bulb with turbulent or slow flow can lead to a loss of the normal flow void and contrast enhancement in the vessel on MR imaging and may mimic true pathology. The CT imaging of the high jugular bulb may demonstrate enlargement and/or dehiscence of the bony canal and lead to the suspicion of a slow-growing mass. However, as shown in the present study, certain anatomic variants of the jugular bulb may be misdiagnosed because of their similarities to tumors based on these imaging techniques. In cases where jugular bulb anatomic variants are suspected, the diagnosis is often confirmed with venous phase images during conventional catheter angiography or with MR venography imaging (3). In the past, cerebral angiography has been the definitive diagnostic tool for this cerebrovascular disease; however, this imaging technique has the disadvantage of being invasive. Recent technologic advances in CT imaging have resulted in the development of noninvasive techniques. CT angiography with three-dimensional volume rendering is a noninvasive technique for accurate and early diagnosis of many neurologic diseases diagnosed by less accurate and more invasive studies in the past. This technique also allows the evaluation of the venous anatomy. To our knowledge, based on a review of the