Page 37 - TI Journal 18-1

Technology and Innovation, Vol. 18, pp. 31-37, 2016 ISSN 1949-8241 • E-ISSN 1949-825X
Printed in the USA. All rights reserved. http://dx.doi.org/10.21300/18.1.2016.31
Copyright © 2016 National Academy of Inventors. www.technologyandinnovation.org

DIFFUSION IMAGING FIBER BUNDLES

Song Zhang

Computer Science and Engineering Department
Mississippi State University, Mississippi State, MS, USA

Diffusion imaging fiber bundles reconstructed from diffusion-weighted images reveal the shape
and size of neural fiber bundles in brain white matter. Further, the global connectivity infor-
mation in the diffusion imaging fiber bundles helps researchers examine the integrity of the
neural bundles and injury from diseases. In this paper, we review the background, the meth-
ods, and the applications of diffusion imaging fibers.
Key words: Diffusion imaging; Diffusion tensor; HARDI; Fiber bundles

INTRODUCTION can be done qualitatively with visualization or quan-
Diffusion imaging (DI) is a type of magnetic res- titatively with metrics on the fiber bundles. Figure 1
onance imaging (MRI) that is widely used to probe shows the pipeline for diffusion imaging fiber bundle
the three dimensional structure of fibrous tissues, analysis. In this paper, we review the key steps in the
such as brain, heart, and muscle, in vivo (20). The generation and analysis of diffusion imaging fiber
method for reconstructing the fibrous structures from bundles with applications in brain white matter.
diffusion weighted images is called tractography (3),
which tracks integral curves following the principal DIFFUSION TENSOR IMAGING
direction of diffusion. The resulting diffusion fibers Diffusion imaging records the diffusion process of
follow biological tissue fibers, such as the white matter water molecules in biological tissues in vivo. Water
pathways. These fibers can be further analyzed to molecules in biological tissues engage in random
understand anatomical structures, check structural Brownian motion from collision with other atoms
integrity, and study the effect of diseases on brain, and molecules. The motion is restricted by micro-
heart, and muscle. An important step in analyzing structures in the tissues. For example, in white matter,
diffusion fibers is to identify groups of fibers that water diffuses faster along the axons but slower per-
are relevant to the study from all the fibers. These pendicular to axons because the motion is restricted
are called tracts-of-interest (9). Manually selecting by the tightly packed multiple myelin membranes
these tracts is both time-consuming and error-prone. encompassing axons (21). This phenomenon of dif-
Hence, automatic fiber bundling methods have been ferent diffusion rate in different directions is called
proposed to group the diffusion fiber into fiber bun- anisotropy, which can be captured by diffusion MRI
dles. Once the fiber bundles are generated, analysis to explore the white matter structures in vivo.
_____________________
Accepted December 10, 2015.
Address correspondence to Song Zhang, Computer Science and Engineering Department, Mississippi State University, Box 9637, Mississippi
State, MS 39762, USA. Tel: +1 (662) 325-7510; E-mail: szhang@cse.msstate.edu

31