Dataset Information

Diffusion Tensor Imaging Tractography of White Matter Tracts in the Equine Brain.

ABSTRACT: Tractography, a noninvasive technique tracing brain pathways from diffusion tensor magnetic resonance imaging (DTI) data, is increasingly being used for brain investigation of domestic mammals. In the equine species, such a technique could be useful to improve our knowledge about structural connectivity or to assess structural changes of white matter tracts potentially associated with neurodegenerative diseases. The goals of the present study were to establish the feasibility of DTI tractography in the equine brain and to provide a morphologic description of the most representative tracts in this species. Postmortem DTI and susceptibility-weighted imaging (SWI) of an equine brain were acquired with a 3-T system using a head coil. Association, commissural, and projection fibers, the three fiber groups typically investigated in tractography studies, were successfully reconstructed and overlaid on SWI or fractional anisotropy maps. The fibers derived from DTI correlate well with their description in anatomical textbooks. Our results demonstrate the feasibility of using postmortem DTI data to reconstruct the main white matter tracts of the equine brain. Further DTI acquisitions and corresponding dissections of equine brains will be necessary to validate these findings and create an equine stereotaxic white matter atlas that could be used in future neuroimaging research.

SUBMITTER: Boucher S

PROVIDER: S-EPMC7406683 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Diffusion Tensor Imaging Tractography of White Matter Tracts in the Equine Brain.

Boucher Samuel S Arribarat Germain G Cartiaux Benjamin B Lallemand Elodie Anne EA Péran Patrice P Deviers Alexandra A Mogicato Giovanni G

Frontiers in veterinary science 20200730

Tractography, a noninvasive technique tracing brain pathways from diffusion tensor magnetic resonance imaging (DTI) data, is increasingly being used for brain investigation of domestic mammals. In the equine species, such a technique could be useful to improve our knowledge about structural connectivity or to assess structural changes of white matter tracts potentially associated with neurodegenerative diseases. The goals of the present study were to establish the feasibility of DTI tractography ...[more]

PMID: 32850994

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Project description:BackgroundCognitive impairment is known to occur in patients with prolactinoma, but the underlying mechanism is unclear.ObjectiveTo evaluate cognitive function in patients with prolactinoma and to investigate the basis of possible cognitive impairment in brain white matter changes using diffusion tensor imaging (DTI).Methods37 consecutive patients with prolactinoma and 37 healthy controls of similar age, sex, and education were enrolled in the study. Hormone levels were determined in all participants, comprehensive neuropsychological testing was performed, and DTI was used to reconstruct and evaluate white matter tracts.ResultsIn patients with prolactinoma, short- and long-term visual and verbal memory, attention, concentration, and executive and language functions were impaired compared to the healthy group. When comparing the DTI results, lower fractional anisotropy (FA) values were found in the patients' right uncinate fasciculus (R-UF), indicating neuronal damage. After applying the Bonferroni correction, the two groups had no significant difference in 42 tracts (p > 0.0012 for all). A positive correlation was found between poor FA scores on the R-UF and low scores on long-term memory, category and letter fluency tests. In addition, patients with hypoprolactinemia had the worst short-term memory scores, while normoprolactinemia had the best scores. Also, the poorer R-UF FA values were found in the patients with hypoprolactinemia and the highest in those with normoprolactinemia.ConclusionThis study is the first to investigate reasons for cognitive dysfunction in patients with prolactinoma by DTI. No significant structural changes were found in brain tracts of patients with prolactinoma. Still, there may be a link between potential damage in the R-UF and cognitive dysfunction, and further research is needed. In addition, the results showed that the development of hypoprolactinemia is associated with cognitive dysfunction and emphasized that overtreatment should be avoided.

Project description:Primary progressive aphasia is a clinical syndrome that encompasses three major phenotypes: non-fluent/agrammatic, semantic and logopenic. These clinical entities have been associated with characteristic patterns of focal grey matter atrophy in left posterior frontoinsular, anterior temporal and left temporoparietal regions, respectively. Recently, network-level dysfunction has been hypothesized but research to date has focused largely on studying grey matter damage. The aim of this study was to assess the integrity of white matter tracts in the different primary progressive aphasia subtypes. We used diffusion tensor imaging in 48 individuals: nine non-fluent, nine semantic, nine logopenic and 21 age-matched controls. Probabilistic tractography was used to identify bilateral inferior longitudinal (anterior, middle, posterior) and uncinate fasciculi (referred to as the ventral pathway); and the superior longitudinal fasciculus segmented into its frontosupramarginal, frontoangular, frontotemporal and temporoparietal components, (referred to as the dorsal pathway). We compared the tracts' mean fractional anisotropy, axial, radial and mean diffusivities for each tract in the different diagnostic categories. The most prominent white matter changes were found in the dorsal pathways in non-fluent patients, in the two ventral pathways and the temporal components of the dorsal pathways in semantic variant, and in the temporoparietal component of the dorsal bundles in logopenic patients. Each of the primary progressive aphasia variants showed different patterns of diffusion tensor metrics alterations: non-fluent patients showed the greatest changes in fractional anisotropy and radial and mean diffusivities; semantic variant patients had severe changes in all metrics; and logopenic patients had the least white matter damage, mainly involving diffusivity, with fractional anisotropy altered only in the temporoparietal component of the dorsal pathway. This study demonstrates that both careful dissection of the main language tracts and consideration of all diffusion tensor metrics are necessary to characterize the white matter changes that occur in the variants of primary progressive aphasia. These results highlight the potential value of diffusion tensor imaging as a new tool in the multimodal diagnostic evaluation of primary progressive aphasia.

Project description:Background and purposeBrain white matter is frequently affected in mitochondrial diseases; optic atrophy gene 1-autosomal dominant optic atrophy and Leber hereditary optic neuropathy are the most frequent mitochondrial monosymptomatic optic neuropathies. In this observational study, brain white matter microstructure was characterized by DTI in patients with optic atrophy gene 1-autosomal dominant optic atrophy and Leber hereditary optic neuropathy, in relation to clinical and genetic features.Materials and methodsNineteen patients with optic atrophy gene 1-autosomal dominant optic atrophy and 17 with Leber hereditary optic neuropathy older than 18 years of age, all genetically diagnosed, and 19 healthy volunteers underwent DTI by using a 1.5T MR imaging scanner and neurologic and ophthalmologic assessments. Brain white matter DTI metrics were calculated for all participants, and, in patients, their correlations with genetics and clinical findings were calculated.ResultsCompared with controls, patients with optic atrophy gene 1-autosomal dominant optic atrophy had an increased mean diffusivity in 29.2% of voxels analyzed within major white matter tracts distributed throughout the brain, while fractional anisotropy was reduced in 30.3% of voxels. For patients with Leber hereditary optic neuropathy, the proportion of altered voxels was only 0.5% and 5.5%, respectively, of which half was found within the optic radiation and 3.5%, in the smaller acoustic radiation. In almost all regions, fractional anisotropy diminished with age in patients with optic atrophy gene 1-autosomal dominant optic atrophy and correlated with average retinal nerve fiber layer thickness in several areas. Mean diffusivity increased in those with a missense mutation. Patients with Leber hereditary optic neuropathy taking idebenone had slightly milder changes.ConclusionsPatients with Leber hereditary optic neuropathy had preferential involvement of the optic and acoustic radiations, consistent with trans-synaptic degeneration, whereas patients with optic atrophy gene 1-autosomal dominant optic atrophy presented with widespread involvement suggestive of a multisystemic, possibly a congenital/developmental, disorder. White matter changes in Leber hereditary optic neuropathy and optic atrophy gene 1-autosomal dominant optic atrophy may be exploitable as biomarkers.

Dataset Information

Diffusion Tensor Imaging Tractography of White Matter Tracts in the Equine Brain.

Publications

Diffusion Tensor Imaging Tractography of White Matter Tracts in the Equine Brain.

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