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Statistical representation of mean diffusivity and fractional anisotropy brain maps of normal subjects

✍ Scribed by Siamak Ardekani; Usha Sinha

Book ID
102904574
Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
889 KB
Volume
24
Category
Article
ISSN
1053-1807

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✦ Synopsis

Abstract

Purpose

To create diffusion tensor atlases from echo planar imaging (EPI) images acquired at 3 T in 10 normal subjects.

Materials and Methods

Data from 10 right‐handed healthy adult volunteers (mean age of 31 ± 3 years; eight males) were acquired using a 3.0‐T scanner. Geometric distortion artifacts correction was accomplished by combining parallel acquisition to reduce the distortion as well as postprocessing by registration to a geometrically accurate T2‐weighted fast‐spin‐echo image. This reduced distortions to within a voxel for most of the internal structures of the brain. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) atlases were created by warping images using an iterative optical‐flow–based local deformation algorithm that used two channels of data: ADC and FA.

Results

A three‐dimensional distance measure was used to evaluate the accuracy of the registration algorithm with contours defined on two structures: the corpus callosum and cerebellum. The average three‐dimensional distance value for the nine subjects (with the 10th as the reference) was 0.2 mm for the corpus callosum and 1.2 mm for the cerebellum.

Conclusion

A high‐resolution, diffusion MR atlas with full brain coverage was developed. Additionally, maps of the SD of the diffusion indices were also generated to provide an estimate of the variance within a normal population. Active shape and texture models were also generated for the corpus callosum as an alternate method of representing the variance in morphology and diffusion indices. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.

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