Automated probabilistic reconstruction of white-matter pathways in health and disease using an atlas of the underlying anatomy

Abstract

We have developed a method for automated probabilistic reconstruction of a set of major white-matter pathways from diffusion-weighted MR images. Our method is called TRACULA (TRActs Constrained by UnderLying Anatomy) and utilizes prior information on the anatomy of the pathways from a set of training subjects. By incorporating this prior knowledge in the reconstruction procedure, our method obviates the need for manual interaction with the tract solutions at a later stage and thus facilitates the application of tractography to large studies. In this paper we illustrate the application of the method on data from a schizophrenia study and investigate whether the inclusion of both patients and healthy subjects in the training set affects our ability to reconstruct the pathways reliably. We show that, since our method does not constrain the exact spatial location or shape of the pathways but only their trajectory relative to the surrounding anatomical structures, a set a of healthy training subjects can be used to reconstruct the pathways accurately in patients as well as in controls.

Differences in the right inferior longitudinal fasciculus but no general disruption of white matter tracts in children with autism spectrum disorder

“…There is no assumption that the pathways have the same shape in the study subjects as in the training subjects, and thus TRACULA does not rely on perfect alignment between study and training subjects. The work of Yendiki et al (42) provides more details on this method, as well as information on its accuracy in healthy participants and those with schizophrenia. Mean values for FA, MD, RD, and axial diffusivity (AD) were obtained for each of the tracts reconstructed by TRACULA.…”

“…These segmentations were then used as part of the diffusion analysis. Anatomically constrained probabilistic diffusion tractography was carried out by using the Tracts Constrained by UnderLying Anatomy (TRACULA) tool within FreeSurfer (42). This algorithm for automated global probabilistic tractography estimates the posterior probability of each of 18 white-matter pathways given the diffusionweighted MRI data of each participant.…”

An MRI study of white matter tract integrity in regular cannabis users: effects of cannabis use and age

“…Diffusion sequences were pre-processed using the TRACULA pipeline (Yendiki et al 2011), which involved eddy-current correction and rotation of b-vectors, followed by brain extraction and co-registration between structures and diffusion (b=0) volumes. Fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) volumes were created using the DTIFIT command from FSL (Smith et al 2004) utilising ordinary least squares tensor fitting.…”

“…An alternative method is to apply expert neuroanatomists' segmentations of major white matter tracts to individual participants (TRActs Constrained by UnderLying Anatomy, TRACULA, (Yendiki et al 2011)) and calculate average white matter integrity over the entire tract. In combining automated methodologies, we utilised the exploratory voxel-based comparison of TBSS together with the overall tract integrity assessment of TRACULA.…”

Brain Mapping Using Neuroimaging

“…TBSS has the advantage of correcting white matter tracks' spatial alignment problem. TRActs Constrained by UnderLying Anatomy (TRACULA) is a fiber tracking method with automated probabilistic reconstruction of 18 major white matter pathways from DTI (Yendiki et al, 2011). It uses prior information of the white matter pathways from a set of training subject which was previously built.…”