Article
Probabilistic DTI based depiction of the facial nerve in vestibular schwannoma
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Published: | June 9, 2017 |
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Objective: According to our previous results, probabilistic tractography might be more successful in depicting cranial nerves compared to the common deterministic method. We have examined the utility of this technique in patients harboring large vestibular schwannomas.
Methods: Data from fifteen patients harbouring Koos Grade 3 and 4 vestibular schwannomas were included in this study. Diffusion weighted and anatomic images were acquired. The probabilistic tracking was run preoperatively and the true position of the nerve was determined intraoperatively by the surgeon. Both positions were compared and the diffusion - based tracking depiction was checked for accuracy.
Results: The depiction of a fiber tract corresponding to the facial nerve was observed in 12 of the 15 cases (80%) as a connection between the brainstem and the internal acoustic meatus. However, in 9 of these 12 (75%) cases, one or more additional pathways were visible in the final depiction, making immediate identification of the true position of the facial nerve impossible. Moreover, in the three remaining subjects (20%), only pathways not corresponding to the facial nerve position were depicted.
Conclusion: Probabilistic tracking between the internal acoustic meatus and the brainstem results in multiple pathways in a majority of cases. Observer’s judgement is necessary to identify the probable position of the facial nerve among the multiple connections.