High-resolution diffusion tensor imaging and tractography of the human optic chiasm at 9.4 T

Roebroeck, Alard; Galuske, Ralf A. W.; Formisano, Elia; Chiry, Oriana; Bratzke, H.; Ronen, Itamar; Kim, Dae‐Shik; Goebel, Rainer

doi:10.1016/j.neuroimage.2007.08.015

Cited by 92 publications

(84 citation statements)

References 46 publications

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“…Our results also suggest that this problem is unlikely to be overcome by using sophisticated HARDI tracking algorithms or by acquiring high-resolution (angular and spatial) DWI data. In this respect, our findings are consistent with an ex vivo DWI tractography study of the human optic chiasm that showed that DWI tractography fails to identify the ipsilateral and contralateral axonal pathways that branch at the optic chiasm, even at a resolution of 156 μm (in-plane) (41). Despite this intrinsic limitation, tractography is likely to remain a widely used tool in neuroscience, because currently it is the only noninvasive method that allows visualization of white matter pathways in vivo.…”

Section: Discussionsupporting

confidence: 89%

Anatomical accuracy of brain connections derived from diffusion MRI tractography is inherently limited

Thomas

İrfanoğlu

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

708

633

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Tractography based on diffusion-weighted MRI (DWI) is widely used for mapping the structural connections of the human brain. Its accuracy is known to be limited by technical factors affecting in vivo data acquisition, such as noise, artifacts, and data undersampling resulting from scan time constraints. It generally is assumed that improvements in data quality and implementation of sophisticated tractography methods will lead to increasingly accurate maps of human anatomical connections. However, assessing the anatomical accuracy of DWI tractography is difficult because of the lack of independent knowledge of the true anatomical connections in humans. Here we investigate the future prospects of DWI-based connectional imaging by applying advanced tractography methods to an ex vivo DWI dataset of the macaque brain. The results of different tractography methods were compared with maps of known axonal projections from previous tracer studies in the macaque. Despite the exceptional quality of the DWI data, none of the methods demonstrated high anatomical accuracy. The methods that showed the highest sensitivity showed the lowest specificity, and vice versa. Additionally, anatomical accuracy was highly dependent upon parameters of the tractography algorithm, with different optimal values for mapping different pathways. These results suggest that there is an inherent limitation in determining long-range anatomical projections based on voxelaveraged estimates of local fiber orientation obtained from DWI data that is unlikely to be overcome by improvements in data acquisition and analysis alone.T he creation of a comprehensive map of the connectional neuroanatomy of the human brain would be a fundamental achievement in neuroscience. However, despite the numerous efforts to date (for a historical review, see ref. 1), creating this map remains a challenge. A major limitation is that the current goldstandard technique for mapping structural connections, which requires the injection of axonal tracers, cannot be used in humans. The introduction of diffusion-weighted MRI (DWI) (2-4) and the subsequent advent of diffusion tensor MRI (DTI) (5) opened the possibility of exploring the structural properties of white matter in the living human brain (6). Local DWI measures are used clinically for the early detection of stroke and for the characterization of neurological disorders such as multiple sclerosis, epilepsy, and brain gliomas, among others (7). In addition, tractography approaches (8-12) that can infer structural brain connectivity based on brain-wide local DWI measurement have been developed (for reviews, see refs. 13 and 14). The success of DWI tractography as a method for studying fiber trajectories has led to a systematic characterization of large white-matter pathways of the living human brain (e.g., ref. 15), and now it is used routinely to provide a structural explanation for aspects of human brain function (16).A major limitation of DWI tractography is that its characterization of axonal pathways is based on indirec...

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Section: Discussionsupporting

confidence: 89%

Anatomical accuracy of brain connections derived from diffusion MRI tractography is inherently limited

Thomas

İrfanoğlu

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

708

633

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“…The course of the decussating fibers has been reported to describe two bends (see Fig. 5A0) (Hoyt and Luis, 1963;Roebroeck et al, 2008). In order to model the human optic chiasm (see Figs.…”

Section: Models Of the Optic Chiasmmentioning

confidence: 99%

Understanding fiber mixture by simulation in 3D Polarized Light Imaging

et al. 2015

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“…The higher the ADC value, the higher the diffusivity. FA value represents the direction of the diffusion and ranges from 0 to 1 where a FA of 0 indicates all directional free diffusion tensor and a FA of 1 indicates one-directional linear tensor [6]. If there are no hindrances to random motions of water, diffusion is the same in all directions and is termed isotropic diffusion (isotropy causes lower FA values).…”

Section: Introductionmentioning

confidence: 99%

Correlation of the measurements of optical coherence tomography and diffuse tension imaging of optic pathways in amblyopia

Altıntaş

Gümüştaş

Cinik³

et al. 2016

Int Ophthalmol

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The aim of this study was to investigate whether a correlation exists between optical coherence tomography (OCT) of retina and diffusion tensor imaging (DTI) of the optic pathway measurements. All subjects underwent OCT measurements of optic nerve head, retinal nerve fiber layer, and macula. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of optic pathways were analyzed using DTI. Prechiasmatic FA values were significantly decreased in unilateral amblyopic group in both affected and sound fellow eyes (p = 0.019 and 0.013), but not in bilateral amblyopic group (p = 0.221) when compared with the control group. ADC values were significantly greater in sound eye in unilateral amblyopic group in prechiasmatic and postchiasmatic regions (p = 0.001 and 0.049). ADC values were also significantly greater in bilateral amblyopic group in postchiasmatic region (p = 0.037). There were no significant differences between the affected eye and sound eye side DTI measurements. There was no significant correlation between prechiasmatic DTI and OCT measurements in affected and sound eyes of unilateral amblyopia group. DTI results demonstrated that there is a functional underdevelopment of the anterior and posterior visual pathways in both affected and sound eye of unilateral amblyopic patients. Significantly reduced FA values in prechiasmatic region where OCT values of retina were normal can be explained by possible micro-structural changes.

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High-resolution diffusion tensor imaging and tractography of the human optic chiasm at 9.4 T

Cited by 92 publications

References 46 publications

Anatomical accuracy of brain connections derived from diffusion MRI tractography is inherently limited

Anatomical accuracy of brain connections derived from diffusion MRI tractography is inherently limited

Understanding fiber mixture by simulation in 3D Polarized Light Imaging

Correlation of the measurements of optical coherence tomography and diffuse tension imaging of optic pathways in amblyopia

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