A Systematic Analysis of the Reliability of Diffusion Tensor Imaging Tractography for Facial Nerve Imaging in Patients with Vestibular Schwannoma

Ung, Nolan; Mathur, Monica; Chung, Lawrance K.; Cremer, Nicole; Pelargos, Panayiotis; Frew, Andrew J.; Thill, Kimberly; Mathur, Ishani; Voth, Brittany; Lim, Michael; Yang, Isaac

doi:10.1055/s-0035-1566303

Cited by 17 publications

(6 citation statements)

References 35 publications

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“…Similarly, a 17% accuracy rate was reported by Yoshino et al when standard DTI was used but this increased to 67% when DTI was combined with multifused CE-FIESTA images (Yoshino et al, 2015a). Excluding these results, the success rate of generating cranial nerve tractography in patients with a posterior fossa tumor rises to 82–100%, similar to that reported by Ung et al in their brief review of the literature (Ung et al, 2016); however, intraoperative accuracy remains inconsistent (30–100%).…”

Section: Discussionsupporting

confidence: 74%

Clinical Applications for Diffusion MRI and Tractography of Cranial Nerves Within the Posterior Fossa: A Systematic Review

et al. 2019

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Objective: This paper presents a systematic review of diffusion MRI (dMRI) and tractography of cranial nerves within the posterior fossa. We assess the effectiveness of the diffusion imaging methods used and examine their clinical applications. Methods: The Pubmed, Web of Science and EMBASE databases were searched from January 1st 1997 to December 11th 2017 to identify relevant publications. Any study reporting the use of diffusion imaging and/or tractography in patients with confirmed cranial nerve pathology was eligible for selection. Study quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) tool. Results: We included 41 studies comprising 16 studies of patients with trigeminal neuralgia (TN), 22 studies of patients with a posterior fossa tumor and three studies of patients with other pathologies. Most acquisition protocols used single-shot echo planar imaging (88%) with a single b-value of 1,000 s/mm 2 (78%) but there was significant variation in the number of gradient directions, in-plane resolution, and slice thickness between studies. dMRI of the trigeminal nerve generated interpretable data in all cases. Analysis of diffusivity measurements found significantly lower fractional anisotropy (FA) values within the root entry zone of nerves affected by TN and FA values were significantly lower in patients with multiple sclerosis. Diffusivity values within the trigeminal nerve correlate with the effectiveness of surgical treatment and there is some evidence that pre-operative measurements may be predictive of treatment outcome. Fiber tractography was performed in 30 studies (73%). Most studies evaluating fiber tractography involved patients with a vestibular schwannoma (82%) and focused on generating tractography of the facial nerve to assist with surgical planning. Deterministic tractography using diffusion tensor imaging was performed in 93% of cases but the reported success rate and accuracy of generating fiber tracts from the acquired diffusion data varied considerably. Conclusions: dMRI has the potential to inform our understanding of the microstructural changes that occur within the cranial nerves in various pathologies. Cranial nerve tractography is a promising technique but new avenues of using dMRI should be explored to optimize and improve its reliability.

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Section: Discussionsupporting

confidence: 74%

Clinical Applications for Diffusion MRI and Tractography of Cranial Nerves Within the Posterior Fossa: A Systematic Review

et al. 2019

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“…Four studies (among the 18 with data applicable to our analysis) were not ultimately considered in our analysis. One study (Ung et al 21 ) was a systematic analysis of FN DTI tractography studies that had been conducted in 2015 and included 3 studies. Another study (Chen et al 3 ) analyzed DTI for tracking the cranial nerves in VS but did not test the reliability of the results as compared with intraoperative findings.…”

Section: Resultsmentioning

confidence: 99%

Preoperative diffusion tensor imaging–fiber tracking for facial nerve identification in vestibular schwannoma: a systematic review on its evolution and current status with a pooled data analysis of surgical concordance rates

Savardekar¹,

Patra²,

Thakur³

et al. 2018

Neurosurgical Focus

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OBJECTIVETotal tumor excision with the preservation of neurological function and quality of life is the goal of modern-day vestibular schwannoma (VS) surgery. Postoperative facial nerve (FN) paralysis is a devastating complication of VS surgery. Determining the course of the FN in relation to a VS preoperatively is invaluable to the neurosurgeon and is likely to enhance surgical safety with respect to FN function. Diffusion tensor imaging–fiber tracking (DTI-FT) technology is slowly gaining traction as a viable tool for preoperative FN visualization in patients with VS.METHODSA systematic review of the literature in the PubMed, Cochrane Library, and Web of Science databases was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and those studies that preoperatively localized the FN in relation to a VS using the DTI-FT technique and verified those preoperative FN tracking results by using microscopic observation and electrophysiological monitoring during microsurgery were included. A pooled analysis of studies was performed to calculate the surgical concordance rate (accuracy) of DTI-FT technology for FN localization.RESULTSFourteen studies included 234 VS patients (male/female ratio 1:1.4, age range 17–75 years) who had undergone preoperative DTI-FT for FN identification. The mean tumor size among the studies ranged from 29 to 41.3 mm. Preoperative DTI-FT could not visualize the FN tract in 8 patients (3.4%) and its findings could not be verified in 3 patients (1.2%), were verified but discordant in 18 patients (7.6%), and were verified and concordant in 205 patients (87.1%).CONCLUSIONSPreoperative DTI-FT for FN identification is a useful adjunct in the surgical planning for large VSs (> 2.5 cm). A pooled analysis showed that DTI-FT successfully identifies the complete FN course in 96.6% of VSs (226 of 234 cases) and that FN identification by DTI-FT is accurate in 90.6% of cases (205 of 226 cases). Larger studies with DTI-FT–integrated neuronavigation are required to look at the direct benefit offered by this specific technique in preserving postoperative FN function.

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“…13,19,20 In the past few years, there have been an increasing number of studies, which use diffusion tensor imaging (DTI) to analyze the spatial relationship of the FN to the tumor. [39][40][41][42] While DTI may provide a detailed analysis of the risk for FN injury, it is susceptible to error. The A/P index provides a simple tool, which can be readily calculated on standard MRI to provide meaningful FN risk assessment.…”

Section: Discussionmentioning

confidence: 99%

Prognostic Indices for Predicting Facial Nerve Outcome following the Resection of Large Acoustic Neuromas

et al. 2017

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This study analyzes the simple ratio of anterior-to-posterior extension of large (>2.5 cm) acoustic neuromas relative to the internal auditory canal (ICA; anterior-posterior [A/P] index) as a tool for predicting risk of facial nerve (FN) injury. In total, 105 patients who underwent microsurgical resection for large acoustic neuromas were analyzed retrospectively. House-Brackmann (HB) scores were assessed immediately postoperatively, at 1 month, and at 1 year. Lateral-medial, inferior-superior, A/P, and maximum diameters were measured from preoperative magnetic resonance images. These measurements and the A/P index were analyzed using univariable and multivariable statistical models to assess relationship to FN outcomes. The retrosigmoid, translabyrinthine, and combined approaches were used, and the extent of resection was evaluated. For every 1 standard deviation increase in the A/P index, a patient was 3.87 times more likely have a higher postoperative HB score ( < 0.0001). Accordingly, for every 1-mm increase anterior to the IAC, a patient was 16% more likely have a higher postoperative HB score ( < 0.001). After controlling for tumor size, a patient was still 3.82 times more likely have a higher postoperative HB score for every 1 standard deviation increase in the A/P index ( < 0.0001). While larger tumor size trended toward worse postoperative HB scores, it was not statistically significant. Our prognostic index may be useful to assess the risk of FN injury preoperatively for large acoustic neuromas, while also providing information about the tumor-nerve relationship.

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A Systematic Analysis of the Reliability of Diffusion Tensor Imaging Tractography for Facial Nerve Imaging in Patients with Vestibular Schwannoma

Cited by 17 publications

References 35 publications

Clinical Applications for Diffusion MRI and Tractography of Cranial Nerves Within the Posterior Fossa: A Systematic Review

Clinical Applications for Diffusion MRI and Tractography of Cranial Nerves Within the Posterior Fossa: A Systematic Review

Preoperative diffusion tensor imaging–fiber tracking for facial nerve identification in vestibular schwannoma: a systematic review on its evolution and current status with a pooled data analysis of surgical concordance rates

Prognostic Indices for Predicting Facial Nerve Outcome following the Resection of Large Acoustic Neuromas

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