Tractography of Meyer's Loop asymmetries

Gervai, Patricia Dreessen de; Sboto-Frankenstein, Uta; Bolster, R. Bruce; Thind, Sunny; Gruwel, Marco L.H.; Smith, Stephen D.; Tomanek, Bogusław

doi:10.1016/j.eplepsyres.2014.03.006

Cited by 27 publications

(20 citation statements)

References 33 publications

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“…Specifically, we find left-ward asymmetry of the optic radiation. This is consistent with post-mortem study results that also found the optic radiation was larger on the left hemisphere on a sample size of 10 (Dreessen de Gervai et al 2014). Our results provide an in vivo validation of this finding on a large HCP cohort.…”

Section: Discussionsupporting

confidence: 91%

“…The final bundle was formed by combining the components, but the typical final product obtained in that study did not form the expected continuous sheet representation of the optic radiation. Asymmetry of the left and right Meyer’s loop was studied by Dreessen de Gervai et al (2014) with the probabilistic tractography tool in MedINRIA (Fillard et al , 2007) on a cohort of 20 healthy subjects. Three sub-bundles of the optic radiation were computed separately with different inclusion ROIs that were manually placed around the LGN.…”

Section: Introductionmentioning

confidence: 99%

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Automated retinofugal visual pathway reconstruction with multi-shell HARDI and FOD-based analysis

et al. 2016

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Diffusion MRI tractography provides a non-invasive modality to examine the human retinofugal projection, which consists of the optic nerves, optic chiasm, optic tracts, the lateral geniculate nuclei (LGN) and the optic radiations. However, the pathway has several anatomic features that make it particularly challenging to study with tractography, including its location near blood vessels and bone-air interface at the base of the cerebrum, crossing fibers at the chiasm, somewhat-tortuous course around the temporal horn via Meyer’s Loop, and multiple closely neighboring fiber bundles. To date, these unique complexities of the visual pathway have impeded the development of a robust and automated reconstruction method using tractography. To overcome these challenges, we develop a novel, fully automated system to reconstruct the retinofugal visual pathway from high-resolution diffusion imaging data. Using multi-shell, high angular resolution diffusion imaging (HARDI) data, we reconstruct precise fiber orientation distributions (FODs) with high order spherical harmonics (SPHARM) to resolve fiber crossings, which allows the tractography algorithm to successfully navigate the complicated anatomy surrounding the retinofugal pathway. We also develop automated algorithms for the identification of ROIs used for fiber bundle reconstruction. In particular, we develop a novel approach to extract the LGN region of interest (ROI) based on intrinsic shape analysis of a fiber bundle computed from a seed region at the optic chiasm to a target at the primary visual cortex. By combining automatically identified ROIs and FOD-based tractography, we obtain a fully automated system to compute the main components of the retinofugal pathway, including the optic tract and the optic radiation. We apply our method to the multi-shell HARDI data of 215 subjects from the Human Connectome Project (HCP). Through comparisons with post-mortem dissection measurements, we demonstrate the retinotopic organization of the optic radiation including a successful reconstruction of Meyer’s loop. Then, using the reconstructed optic radiation bundle from the HCP cohort, we construct a probabilistic atlas and demonstrate its consistency with a post-mortem atlas. Finally, we generate a shape-based representation of the optic radiation for morphometry analysis.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Automated retinofugal visual pathway reconstruction with multi-shell HARDI and FOD-based analysis

et al. 2016

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“…Despite the high anatomical variability and marked asymmetry that is associated with the distance of Meyer's Loop to the temporal pole between hemispheres (Bürgel et al, 2006;Jeelani et al, 2010;Dreessen de Gervai et al, 2014), in this study we were able to successfully map the optic radiation in all subjects. In particular, we were able to do so in a pediatric surgical cohort and show, to the best of our knowledge, the first report that relates the degree and location of resection extent with optic radiation involvement in a pediatric surgical series.…”

Section: Clinical Correlations With Tractographymentioning

confidence: 77%

Microstructural Investigations of the Visual Pathways in Pediatric Epilepsy Neurosurgery: Insights From Multi-Shell Diffusion Magnetic Resonance Imaging

et al. 2020

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Background: Surgery is a key approach for achieving seizure freedom in children with focal onset epilepsy. However, the resection can affect or be in the vicinity of the optic radiations. Multi-shell diffusion MRI and tractography can better characterize tissue structure and provide guidance to help minimize surgical related deficits. Whilst in adults tractography has been used to demonstrate that damage to the optic radiations leads to postoperative visual field deficits, this approach has yet to be properly explored in children.Objective: To demonstrate the capabilities of multi-shell diffusion MRI and tractography in characterizing microstructural changes in children with epilepsy pre-and post-surgery affecting the occipital, parietal or temporal lobes.Methods: Diffusion Tensor Imaging and the Spherical Mean Technique were used to investigate the microstructure of the optic radiations. Furthermore, tractography was used to evaluate whether pre-surgical reconstructions of the optic radiations overlap with the resection margin as measured using anatomical post-surgical T1weighted MRI.Results: Increased diffusivity in patients compared to controls at baseline was observed with evidence of decreased diffusivity, anisotropy, and neurite orientation distribution in contralateral hemisphere after surgery. Pre-surgical optic radiation tractography overlapped with post-surgical resection margins in 20/43 (46%) children, and where visual data was available before and after surgery, the presence of overlap indicated a visual field deficit. Frontiers in Neuroscience | www.frontiersin.org 1 April 2020 | Volume 14 | Article 269 Lacerda et al. Visual Pathways in Pediatric SurgeryConclusion: This is the first report in a pediatric series which highlights the relevance of tractography for future pre-surgical evaluation in children undergoing epilepsy surgery and the usefulness of multi-shell diffusion MRI to characterize brain microstructure in these patients.

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“…Nevertheless, having lateralised results are not surprising: several studies showed asymmetric function and structure in the visual system (Antal et al, 2004;Dreessen de Gervai et al, 2014).…”

Section: Discussionmentioning

confidence: 91%

Audio–visual integration through the parallel visual pathways

et al. 2015

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Audio-visual integration has been shown to be present in a wide range of different conditions, some of which are processed through the dorsal, and others through the ventral visual pathway. Whereas neuroimaging studies have revealed integration-related activity in the brain, there has been no imaging study of the possible role of segregated visual streams in audio-visual integration. We set out to determine how the different visual pathways participate in this communication. We investigated how audio-visual integration can be supported through the dorsal and ventral visual pathways during the double flash illusion. Low-contrast and chromatic isoluminant stimuli were used to drive preferably the dorsal and ventral pathways, respectively. In order to identify the anatomical substrates of the audio-visual interaction in the two conditions, the psychophysical results were correlated with the white matter integrity as measured by diffusion tensor imaging.The psychophysiological data revealed a robust double flash illusion in both conditions. A correlation between the psychophysical results and local fractional anisotropy was found in the occipito-parietal white matter in the low-contrast condition, while a similar correlation was found in the infero-temporal white matter in the chromatic isoluminant condition. Our results indicate that both of the parallel visual pathways may play a role in the audio-visual interaction.

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Tractography of Meyer's Loop asymmetries

Cited by 27 publications

References 33 publications

Automated retinofugal visual pathway reconstruction with multi-shell HARDI and FOD-based analysis

Automated retinofugal visual pathway reconstruction with multi-shell HARDI and FOD-based analysis

Microstructural Investigations of the Visual Pathways in Pediatric Epilepsy Neurosurgery: Insights From Multi-Shell Diffusion Magnetic Resonance Imaging

Audio–visual integration through the parallel visual pathways

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