Evaluation of vestibulocochlear nerves in cases with acoustic schwannoma by direct sagittal oblique 3D-FIESTA MR imaging

Abstract

Oblique sagittal MRI with 3D-FIESTA (3-D fast imaging employing steady-state acquisition) sequences can be obtained through the internal auditory canal (IAC) without relying on multi-planar reconstructions. The high spatial resolution direct sagittal oblique imaging technique is useful for the identification of the four intracanalicular nerves. This work included one case of IAC tumor and two cases of cerebellopontine angle (CPA) tumors. MR imaging using a 3D-FIESTA sequence was performed in the oblique sagittal plane perpendicular to the course of the IAC. The direct sagittal oblique imaging technique allowed clear delineation of the individual nerves of the IAC. In a case of acoustic schwannoma, which was surgically proven to originate from the inferior vestibular nerve (IVN), the results of vestibular assessment indicated an IVN pathology. Acquired cochlear nerve hypoplasia with moderate hearing loss was found in a case of CPA tumor.