Diffusion Tensor Magnetic Resonance Imaging Strategies for Color Mapping of Human Brain Anatomy

Said Boujraf

Abstract


A color mapping of fber tract orientation using diffusion tensor imaging (DTI) can be prominent
in clinical practice. The goal of this paper is to perform a comparative study of visualized diffusion
anisotropy in the human brain anatomical entities using three different color‑mapping techniques
based on diffusion‑weighted imaging (DWI) and DTI. The frst technique is based on calculating
a color map from DWIs measured in three perpendicular directions. The second technique is based
on eigenvalues derived from the diffusion tensor. The last technique is based on three eigenvectors
corresponding to sorted eigenvalues derived from the diffusion tensor. All magnetic resonance
imaging measurements were achieved using a 1.5 Tesla Siemens Vision whole body imaging system.
A single‑shot DW echoplanar imaging sequence used a Stejskal–Tanner approach. Trapezoidal
diffusion gradients are used. The slice orientation was transverse. The basic measurement yielded
a set of 13 images. Each series consists of a single image without diffusion weighting, besides two
DWIs for each of the next six noncollinear magnetic feld gradient directions. The three types of color
maps were calculated consequently using the DWI obtained and the DTI. Indeed, we established an
excellent similarity between the image data in the color maps and the fber directions of known
anatomical structures (e.g., corpus callosum and gray matter). In the meantime, rotationally invariant
quantities such as the eigenvectors of the diffusion tensor reflected better, the real orientation found
in the studied tissue.


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