A M Halawani1,2,3, S Tohyama1,4, P S-P Hung1,4, B Behan5, M Bernstein6,7, S Kalia6,7, G Zadeh6,8, M Cusimano6,9, M Schwartz10, F Gentili6,7, D J Mikulis1,2,3, N J Laperriere11,12, M Hodaie13,4,6,7. 1. From the Division of Brain Imaging, and Behaviour-Systems Neuroscience (A.M.H., S.T., P.S.-P.H., D.J.M., M.H.), Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada. 2. Department of Medical Imaging (A.M.H., D.J.M.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. 3. Division of Neuroradiology (A.M.H., D.J.M.), Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada. 4. Institute of Medical Science, (S.T., P.S.-P.H., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. 5. Ontario Brain Institute (B.B.), Toronto, Ontario, Canada. 6. Department of Surgery (M.B., S.K., G.Z., M.C., F.G., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada. 7. Division of Neurosurgery (M.B., S.K., F.G., M.H.), Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada. 8. The Arthur and Sonia Labatt Brain Tumor Research Centre (G.Z.), Hospital for Sick Children, Toronto, Ontario, Canada. 9. Division of Neurosurgery (M.C.), Saint Michael's Hospital, Toronto, Ontario, Canada. 10. Division of Neurosurgery (M.S.), Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada. 11. Department of Radiation Oncology (N.J.L.), University of Toronto, Toronto, Ontario, Canada. 12. Division of Radiation Oncology (N.J.L.), Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada. 13. From the Division of Brain Imaging, and Behaviour-Systems Neuroscience (A.M.H., S.T., P.S.-P.H., D.J.M., M.H.), Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada mojgan.hodaie@uhn.ca.
Abstract
BACKGROUND AND PURPOSE: Vestibular schwannomas are common cerebellopontine angle tumors arising from the vestibulocochlear nerve and can result in cranial nerve dysfunction. Conventional MR imaging does not provide information that could correlate with cranial nerve compression symptoms of hearing loss or imbalance. We used multitensor tractography to evaluate the relationship between the WM microstructural properties of cranial nerves and tumor volume in a cohort of patients with vestibular schwannomas. MATERIALS AND METHODS: A retrospective study was performed in 258 patients with vestibular schwannomas treated at the Gamma Knife clinic at Toronto Western Hospital between 2014 and 2018. 3T MR images were analyzed in 160 surgically naïve patients with unilateral vestibular schwannomas. Multitensor tractography was used to extract DTI-derived metrics (fractional anisotropy and radial, axial, and mean diffusivities of the bilateral facial and vestibulocochlear nerves [cranial nerves VII/VIII]). ROIs were placed in the transition between cisternal and intracanalicular segments, and images were analyzed using the eXtended Streamline Tractography reconstruction method. Diffusion metrics were correlated with 3D tumor volume derived from the Gamma Knife clinic. RESULTS: DTI analyses revealed significantly higher fractional anisotropy values and a reduction in axial diffusivity, radial diffusivity, and mean diffusivity (all P < .001) within the affected cranial nerves VII and VIII compared with unaffected side. All specific diffusivities (axial, radial, and mean diffusivity) demonstrated an inverse correlation with tumor volume (axial, radial, and mean diffusivity, P < .01). CONCLUSIONS: Multitensor tractography allows the quantification of cranial nerve VII and VIII WM microstructural alterations in patients with vestibular schwannomas. Our findings support the hypothesis that tumor volume may cause microstructural alterations of the affected cranial nerves VII and VIII. This type of advanced imaging may represent a possible avenue to correlate diffusivities with cranial nerve function.
BACKGROUND AND PURPOSE: Vestibular schwannomas are common cerebellopontine angle tumors arising from the vestibulocochlear nerve and can result in cranial nerve dysfunction. Conventional MR imaging does not provide information that could correlate with cranial nerve compression symptoms of hearing loss or imbalance. We used multitensor tractography to evaluate the relationship between the WM microstructural properties of cranial nerves and tumor volume in a cohort of patients with vestibular schwannomas. MATERIALS AND METHODS: A retrospective study was performed in 258 patients with vestibular schwannomas treated at the Gamma Knife clinic at Toronto Western Hospital between 2014 and 2018. 3T MR images were analyzed in 160 surgically naïve patients with unilateral vestibular schwannomas. Multitensor tractography was used to extract DTI-derived metrics (fractional anisotropy and radial, axial, and mean diffusivities of the bilateral facial and vestibulocochlear nerves [cranial nerves VII/VIII]). ROIs were placed in the transition between cisternal and intracanalicular segments, and images were analyzed using the eXtended Streamline Tractography reconstruction method. Diffusion metrics were correlated with 3D tumor volume derived from the Gamma Knife clinic. RESULTS: DTI analyses revealed significantly higher fractional anisotropy values and a reduction in axial diffusivity, radial diffusivity, and mean diffusivity (all P < .001) within the affected cranial nerves VII and VIII compared with unaffected side. All specific diffusivities (axial, radial, and mean diffusivity) demonstrated an inverse correlation with tumor volume (axial, radial, and mean diffusivity, P < .01). CONCLUSIONS: Multitensor tractography allows the quantification of cranial nerve VII and VIII WM microstructural alterations in patients with vestibular schwannomas. Our findings support the hypothesis that tumor volume may cause microstructural alterations of the affected cranial nerves VII and VIII. This type of advanced imaging may represent a possible avenue to correlate diffusivities with cranial nerve function.
Authors: Richard J Kennedy; Clough Shelton; Karen L Salzman; H Christian Davidson; H Ric Harnsberger Journal: Otol Neurotol Date: 2004-03 Impact factor: 2.311