Magnetic Resonance Imaging of the Cavernous Sinus 187

The magnetic resonance (MR) appearance of the cavernous sinus was studied by correlating the MR images of normal volunteers and cryomicrotomic sections from six cadavers. In addition, MR images of patients with parasellar masses were compared with corresponding intravenously enhanced computed tomographic (CT) scans. The MR appearance of the cranial nerves in the cavernous sinuses is demonstrated, as well as MR signs of a parasellar mass, including obliteration of intracavernous venous spaces, displacement of the intracavernous internal carotid artery, and bulging of the lateral wall of the cavernus sinus. MR proved to be more effective than CT in delineating the parts of the cavernous sinus. Magnetic resonance (MR) imaging has the potential to demonstrate the intracavernous segments of cranial nerves in contrast to the negligible signals of flowing blood. Our article describes the normal MR appearance of the cavernous sinuses and the MR signs of cavernous sinus lesions. Materials and Methods Six fresh frozen cadaver heads were embedded in styrofoam boxes with a solution of carboxymethyl cellulose gel. The orbitomeatal lines and sellae turcicae were identified with fluoroscopy. With a horizontally cutting heavy-duty sledge cryomicrotome (LKB 2250) and serial photography of the surfaces of the specimens (1), anatomic images of the cavernous sinuses were obtained in planes parallel or perpendicular to the orbitomeatal line. In the anatomic images, the intracavernous segments of cranial nerves III-VI and of the internal carotid arteries (ICAs) were identified using published anatomic, computed tomographic (CT), and MR literature (2-6). A group of seven normal volunteers and 15 patients were chosen for MR imaging. The patients included two with pituitary adenomas involving cavernous sinuses and one with a parasellar aneurysm . The diagnoses were verified with conventional clinical, CT , angiographic, and surgical (two cases) findings . The volunteers and patients were studied in prototype 1.3, 1.4, or 1.5 T General Electric MR scanners. Initially , a partial saturation (PS) sagittal image was used to determine locations for axial and coronal PS , inversion recovery (IR ), and spin-echo (SE) imaging . Sections parallel (axial plane) and/or perpendicular (coronal plane) to the orbitomeatal line were obtained

Differentiation of Intramedullary Neoplasms and Cysts by MR

527 To determine the MR criteria that are effective for differentiating intramedullary neoplasms from syringo-or hydromyelia, we reviewed MR scans made on prototype and commercial imagers of 33 patients with surgically confirmed cord abnormalities, including nine intramedullary neoplasms and 20 cysts (syringo-or hydromyelia). Two radiologists who did not know the clinical and radiologic diagnoses were asked to evaluate the scans with respect to (1) cord expansion, (2) distinctness of the disease margin, (3) homogeneity, and (4) signal intensity. These observations were correlated with the proved diagnoses. The combination of distinct margins and uniform signal intensity equal to that of CSF correlated consistently (88%) with spinal cord cysts. Other combinations were less reliable for diagnosing a cyst or tumor