gms | German Medical Science

66th Annual Meeting of the German Society of Neurosurgery (DGNC)
Friendship Meeting with the Italian Society of Neurosurgery (SINch)

German Society of Neurosurgery (DGNC)

7 - 10 June 2015, Karlsruhe

Article

Send article

nTMS-based DTI fibertracking of language pathways using fractional anisotropy threshold

Meeting Abstract

Search Medline for

  • Chiara Negwer - Neurochirurgische Klinik und Poliklinik, Klinikum rechts der Isar der TU München; TUM-Neuroimaging Center, München
  • Sebastian Ille - Neurochirurgische Klinik und Poliklinik, Klinikum rechts der Isar der TU München; TUM-Neuroimaging Center, München
  • Nico Sollmann - Neurochirurgische Klinik und Poliklinik, Klinikum rechts der Isar der TU München; TUM-Neuroimaging Center, München
  • Theresa Hauck - Neurochirurgische Klinik und Poliklinik, Klinikum rechts der Isar der TU München; TUM-Neuroimaging Center, München
  • Bernhard Meyer - Neurochirurgische Klinik und Poliklinik, Klinikum rechts der Isar der TU München
  • Sandro M. Krieg - Neurochirurgische Klinik und Poliklinik, Klinikum rechts der Isar der TU München; TUM-Neuroimaging Center, München

Deutsche Gesellschaft für Neurochirurgie. 66. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Karlsruhe, 07.-10.06.2015. Düsseldorf: German Medical Science GMS Publishing House; 2015. DocMI.10.03

doi: 10.3205/15dgnc309, urn:nbn:de:0183-15dgnc3091

Published: June 2, 2015

© 2015 Negwer et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.

Outline

Text

Objective: Repetitive navigated transcranial magnetic stimulation (rTMS) is an established method for preoperative language mapping, especially in patients with eloquent gliomas. Previous studies showed the feasibility of TMS based DTI-fibertracking (DTI-FT) for visualization of subcortical fibers for the corticospinal tract (CST). Since proved for nTMS-based motor mapping and tractography of CST, this study analyses the application of a fractional anisotropy-based protocol to nTMS-based DTI fibertracking of subcortical language-related fibertracts.

Method: 38 patients with left-sided perisylvian lesions underwent language mapping by rTMS. DTI FT was performed with the protocol published for the corticospinal tract (CST) by Frey et. al in 2012: The fiberlength was set to 110 mm, fractional anisotropy was chosen using the value that showed minimal number of fibers, this setting then was defined as a fractional anisotropy threshold (FAT) of 100%. DTI-FT, using Brainlab iPlanNet 3.0 as deterministic tractography software, was performed using FAT of 100%, 75%, 50%, and 25% (in this study FT was performed with 25% FAT as an additional setting to the original Frey Protocol).

Results: By using the modified Frey protocol we could visualize all known language-related fiber tracts such as corticonuclear tract, arcuate fascicle, uncinate fascicle, superior longitudinal fascicle, inferior longitudinal fascicle, arcuate fibers, commissural fibers, corticothalamic fibers, and frontooccipital fascicle. Using an FAT of 100% the mean percentage of visualized tracts was 13.7%. Respectively using FAT of 75%, 50% and 25% showed 30.4%, 61.4% and 93.9% of language related fiber tracts in the examined patients.

Conclusions: This study shows that the protocol created by Frey et. al (2012) for nTMS-based tracking of the CST is feasible for language related rTMS-based DTI-FT but with optimal results at a reduced FA of 25% FAT in contrast to the CST protocol. Yet, it provides an easy and standardizable tool for clinical routine.