Characterization of ten white matter tracts in a representative sample of Cuban population.

D Góngora,M Domínguez,M A Bobes

doi:10.1186/s12880-016-0163-7

Abstract

BackgroundThe diffusion tensor imaging technique (DTI) combined with tractography methods, has achieved the tridimensional reconstruction of white matter tracts in the brain. It allows their characterization in vivo in a non-invasive way. However, one of the largest sources of variability originates from the location of regions of interest, is therefore necessary schemes which make it possible to establish a protocol to be insensitive to variations in drawing thereof. The purpose of this paper is to stablish a reliable protocol to reconstruct ten prominent tracts of white matter and characterize them according to volume, fractional anisotropy and mean diffusivity. Also we explored the relationship among these factors with gender and hemispheric symmetry.MethodsThis study aims to characterize ten prominent tracts of white matter in a representative sample of Cuban population using this technique, including 84 healthy subjects. Diffusion tensors and subsequently fractional anisotropy and mean diffusivity maps were calculated from each subject’s DTI scans. The trajectory of ten brain tracts was estimated by using deterministic tractography methods of fiber tracking. In such tracts, the volume, the FA and MD were calculated, creating a reference for their study in the Cuban population. The interactions between these variables with age, cerebral hemispheres and gender factors were explored using Repeated Measure Analysis of Variance.ResultsThe volume values showed that a most part of tracts have bigger volume in left hemisphere. Also, the data showed bigger values of MD for males than females in all the tracts, an inverse behavior than FA values.ConclusionsThis work showed that is possible reconstruct white matter tracts using a unique region of interest scheme defined from standard to native space. Also, this study indicates differing developmental trajectories in white matter for males and females and the importance of taking gender into account in developmental DTI studies and in underlie gender-related cognitive differences.Electronic supplementary materialThe online version of this article (doi:10.1186/s12880-016-0163-7) contains supplementary material, which is available to authorized users.

Highlights

The diffusion tensor imaging technique (DTI) combined with tractography methods, has achieved the tridimensional reconstruction of white matter tracts in the brain
To establish and validate reconstruction procedures of trajectories of white matter tracts in humans, reproducible between subjects, is crucial to allow an understandable use of this technique. Given this background and the fact that there are variations in brain anatomy in terms of factors such as hemispheric symmetry, gender and studied population [13], the purpose of this paper is to reconstruct ten prominent tracts of white matter and characterize them according to volume, Fractional Anisotropy (FA) and Mean Diffusivity (MD)
The Region of interest (ROI) that defined tracts’s trajectories were drawn on anatomical reference image from Montreal Neurological Institute (MNI) steoreotaxic space according to the anatomical description reported for Mori et al [8] and validated for Wakana et al [7, 21]. Our data probed their reliability. These authors drawn the ROIs on each individual brain; we drawn the ROIs on MNI space and automatically were transformed to native space of each individual allowing the optimization of ROIs procedure and diminish the time needed for their analysis and the inter-subject variability

Summary

Introduction

The diffusion tensor imaging technique (DTI) combined with tractography methods, has achieved the tridimensional reconstruction of white matter tracts in the brain. It allows their characterization in vivo in a noninvasive way. The purpose of this paper is to stablish a reliable protocol to reconstruct ten prominent tracts of white matter and characterize them according to volume, fractional anisotropy and mean diffusivity. The FACT method allows a good characterization of white matter tracts In healthy subjects, this characterization is required to permit patterns analysis of brain connectivity, and to make comparisons with pathological conditions. It was used small samples (less than 30 subjects), mostly Caucasian populations without emphasis in variables that characterize the peculiarities of each tract [7,8,9]

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