Article
Diffusion-based visualisation of the facial nerve in vestibular schwannoma with RESOLVE DWI – preliminary results
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Authors
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Amir Zolal
- Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Carl Gustav Carus der Technischen Universität Dresden
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Gabriele Schackert
- Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Carl Gustav Carus der Technischen Universität Dresden
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Stephan B. Sobottka
- Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Carl Gustav Carus der Technischen Universität Dresden
| Published: | June 2, 2015 |
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Outline
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Objective: The visualisation of the facial nerve with diffusion based techniques is a difficult task even under anatomical conditions, given the small size of the normal facial nerve (< 1 mm thickness). Consequently, most of the volume of the DWI voxel (around 2 mm) being occupied by water. There have been reports on visualization of the facial nerve in vestibular schwannomas (VS), however, routine use has not been reported. The aim of this study is to improve upon the previously described techniques and to establish the accuracy of the method.
Method: Five patients with VS have been included in this preliminary study. A syngo RESOLVE DWI sequence (Siemens, Erlangen, Germany) was acquired in addition to anatomical sequences. Nerve visualization was attempted with deterministic (Brainlab iPlan) and probabilistic (FSL) tracking. No manual fiber exclusion on the result was performed. Various thresholds of the fractional anisotropy and probability index were used. The comparison of the tracking results with the intraoperative finding is reported.
Results: Using the iPlan deterministic tracking method, a fascicle corresponding to the anatomical location of the facial nerve could be identified in 1 case out of 5 (20%). Using the FSL probabilistic tracking, a fascicle corresponding to the anatomical location of the facial nerve was identified in 4 cases out of 5 (80%).
Conclusions: The preliminary results show that without manual fiber exclusion, FSL based probabilistic tracking is superior to the deterministic method.
