RT Journal Article SR Electronic T1 Multishell Diffusion MRI–Based Tractography of the Facial Nerve in Vestibular Schwannoma JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology DO 10.3174/ajnr.A6706 A1 M. Castellaro A1 M. Moretto A1 V. Baro A1 S. Brigadoi A1 E. Zanoletti A1 M. Anglani A1 L. Denaro A1 R. Dell’Acqua A1 A. Landi A1 F. Causin A1 D. d’Avella A1 A. Bertoldo YR 2020 UL http://www.ajnr.org/content/early/2020/07/30/ajnr.A6706.abstract AB BACKGROUND AND PURPOSE: Tractography of the facial nerve based on single-shell diffusion MR imaging is thought to be helpful before surgery for resection of vestibular schwannoma. However, this paradigm can be vitiated by the isotropic diffusion of the CSF, the convoluted path of the facial nerve, and its crossing with other bundles. Here we propose a multishell diffusion MR imaging acquisition scheme combined with probabilistic tractography that has the potential to provide a presurgical facial nerve reconstruction uncontaminated by such effects.MATERIALS AND METHODS: Five patients scheduled for vestibular schwannoma resection underwent multishell diffusion MR imaging (b-values = 0, 300, 1000, 2000 s/mm2). Facial nerve tractography was performed with a probabilistic algorithm and anatomic seeds located in the brain stem, cerebellopontine cistern, and internal auditory canal. A single-shell diffusion MR imaging (b-value = 0, 1000 s/mm2) subset was extrapolated from the multishell diffusion MR imaging data. The quality of the facial nerve reconstruction based on both multishell diffusion MR imaging and single-shell diffusion MR imaging sequences was assessed against intraoperative videos recorded during the operation.RESULTS: Single-shell diffusion MR imaging–based tractography was characterized by failures in facial nerve tracking (2/5 cases) and inaccurate facial nerve reconstructions displaying false-positives and partial volume effects. In contrast, multishell diffusion MR imaging–based tractography provided accurate facial nerve reconstructions (4/5 cases), even in the presence of ostensibly complex patterns.CONCLUSIONS: In comparison with single-shell diffusion MR imaging, the combination of multishell diffusion MR imaging–based tractography and probabilistic algorithms is a more valuable aid for surgeons before vestibular schwannoma resection, providing more accurate facial nerve reconstructions, which may ultimately improve the postsurgical patient’s outcome.dMRIdiffusion MRIFNfacial nerveiFOD2second-order integration over fiber orientation distributionsMSmultishellPVEpartial volume effectSD-STREAMstreamlines tractography based on spherical deconvolutionSSsingle-shellVSvestibular schwannoma