Magnetic Resonance Imaging of the Cavernous Sinus and Cranial Nerves

Introduction: Recent advances in neuroimaging have allowed better visualization of the cavernous sinus and its contents. This study evaluates the efficacy of a T2 MRI sequence to identify the cranial nerves and surrounding anatomy in a cadaver population.

Methods: The intracavernous CNs III, IV, V1, V2, and VI were evaluated on MR imaging in 15 cadavers (7 men, 8 women; mean range, 48–105 years). Unenhanced thin-slice coronal heavily T2-weighted MR sequences were obtained. Source images were reconstructed on a commercial workstation, which allowed reformatting at 0.5-mm intervals with MP reconstructions. The cavernous sinuses were dissected using a simulated microsurgical approach, and observations correlated with the neuroimaging findings. Four cavernous sinuses were obtained for histology. The slides were stained with hematoxylin and eosin and Masson's trichrome stain.

Results: Detectability of intracavernous segments of CNs III, IV, V1, V2, and VI were evaluated on MR imaging with good visualization of the cranial nerves in 86% of cases. Using MPR methods, the course of the cranial nerves could be visualized from their entry and exit points to the cavernous sinus. This correlated with the microanatomical dissections.

Conclusions: Thin-slice heavily T2-weighted MR imaging with reformatting offers clear images of the CNs and dural boundaries of the cavernous sinus, which provides the ability to assess the cavernous carotid artery. This sequence may contribute to the diagnosis and treatment of cavernous sinus pathologies, including meningioma, schwannoma, pituitary adenoma, and aneurysm.