Multishell Diffusion MRI–Based Tractography of the Facial Nerve in Vestibular Schwannoma

Abstract

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 (bvalues ¼ 0, 300, 1000, 2000 s/mm 2 ). 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 ¼ 0, 1000 s/mm 2 ) 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.

Automatic oculomotor nerve identification based on data‐driven fiber clustering

“…Tractography methods are widely used in cranial nerve studies (Behan et al, 2017; Castellaro et al, 2020; He et al, 2021; Hodaie et al, 2010). To find a better method for OCN reconstruction, we compare the performance of three different direction estimation methods including constraint spherical deconvolution (CSD; Behan et al, 2017; Tournier, Calamante, & Connelly, 2012), multi‐shell multi‐tissue constraint spherical deconvolution (MSMT‐CSD), and DTI (Hodaie et al, 2010) to reconstruct the 3D trajectory of OCN.…”

“…To find a better method for OCN reconstruction, we compare the performance of three different direction estimation methods including constraint spherical deconvolution (CSD; Behan et al, 2017; Tournier, Calamante, & Connelly, 2012), multi‐shell multi‐tissue constraint spherical deconvolution (MSMT‐CSD), and DTI (Hodaie et al, 2010) to reconstruct the 3D trajectory of OCN. In contrast to CSD and DTI, MSMT‐CSD is utilized to fit a five‐tissue‐type segmented tissue image by using multiple b ‐values for the multi‐type tissue fiber orientation distribution (FOD; Castellaro et al, 2020; Jeurissen, Tournier, Dhollander, Connelly, & Sijbers, 2014). To describe the complete OCN pathway, we prepare a careful plan for each method, including the seed imaging, ROAs, and parameters.…”

“…According to our experimental results (Table 1. and shells and tissues to estimate fiber directions in each voxel (Castellaro et al, 2020). Tissues respond differently with changes in b-value, and different tissues can be effectively distinguished on the basis of their different response functions (i.e., WM, GM, CSF) (Castellaro et al, 2020;Jeurissen et al, 2014).…”

Advances in Multidisciplinary Management of Skull Base Meningiomas

“…Diffusion MRI and tractography currently represent the only way to reconstruct white matter in humans in vivo, providing a non-invasive and feasible method for evaluating the subcortical pathways changes, especially in glioma surgery [ 21 , 22 , 23 ]. In recent years, its use has been gradually spread for preoperative cranial nerve reconstruction in SBM surgery [ 24 , 25 , 26 ]. In the latter clinical setting, probabilistic tractography currently appears to be an emerging and promising tool to predict the position of displaced cranial nerves around skull base lesions [ 24 , 25 ].…”

“…In addition, the main challenging limitations in cranial nerves tacking are represented by their small size, intricate anatomical environment sensitive to susceptibility artifacts, and a limited MRI spatial and angular resolution. Nevertheless, recent studies have demonstrated effective tracking for large cranial nerves such as optic nerve, trigeminal nerve, or acoustic-facial bundle, highlighting the potential role of tractography both in a surgical setting and intraoperative strategy [ 25 , 26 ].…”