Abstract
BACKGROUND AND PURPOSE: MR imaging is not routinely used to image the extracranial facial nerve. The purpose of this study was to determine the extent to which this nerve can be visualized with a CISS sequence and to determine the feasibility of using that sequence for locating the nerve relative to tumor.
MATERIALS AND METHODS: Thirty-two facial nerves in 16 healthy subjects and 4 facial nerves in 4 subjects with parotid gland tumors were imaged with an axial CISS sequence protocol that included 0.8-mm isotropic voxels on a 3T MR imaging system with a 64-channel head/neck coil. Four observers independently segmented the 32 healthy subject nerves. Segmentations were compared by calculating average Hausdorff distance values and Dice similarity coefficients.
RESULTS: The primary bifurcation of the extracranial facial nerve into the superior temporofacial and inferior cervicofacial trunks was visible on all 128 segmentations. The mean of the average Hausdorff distances was 1.2 mm (range, 0.3–4.6 mm). Dice coefficients ranged from 0.40 to 0.82. The relative position of the facial nerve to the tumor could be inferred in all 4 tumor cases.
CONCLUSIONS: The facial nerve can be seen on CISS images from the stylomastoid foramen to the temporofacial and cervicofacial trunks, proximal to the parotid plexus. Use of a CISS protocol is feasible in the clinical setting to determine the location of the facial nerve relative to tumor.
Footnotes
This work was supported by the American Society of Head and Neck Radiology through the 2017 William N. Hanafee Research Grant. Jagadeesan Jayender, PhD, was supported by the National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, through grant No. P41EB015898.
Disclosures: Jeffrey P. Guenette—RELATED: Grant: American Society of Head and Neck Radiology, Comments: 2017 William N, Hanafee Research Grant.* Ravi Teja Seethamraju—UNRELATED: Employment: Siemens Medical Solutions USA; Patents (Planned, Pending or Issued): Siemens Healthineers; Stock/Stock Options: Siemens Healthineers. Jagadeesan Jayender—RELATED: Grant: National Institutes of Health, Comments: P41EB015898*; UNRELATED: Board Membership: Navigation Sciences; Consultancy: Navigation Sciences, HMDmd; Grants/Grants Pending: National Institutes of Health, Siemens, Comments: R01DK119269 and R01EB025964, research grant from Siemens Medical USA*; Patents (Planned, Pending or Issued): system and method for a tissue resection margin measurement device*; Royalties: Navigation Sciences*; Stock/Stock Options: Navigation Sciences, HMDmd. *Money paid to the institution.
Paper previously presented, in part, at: Annual Meeting of the American Society of Head and Neck Radiology, September 26–30, 2018; Savannah, Georgia.
- © 2019 by American Journal of Neuroradiology