Correction for distortion of echo‐planar images used to calculate the apparent diffusion coefficient

Haselgrove, John C.; Moore, Jason Z.

doi:10.1002/mrm.1910360620

Cited by 298 publications

(268 citation statements)

References 5 publications

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“…72,73 An interesting approach is to use a mutual information criterion to determine a warp that maximizes the overlap within a series of diffusion-weighted images. 57,74 Other post-processing methods that have been proposed include correcting the phase map using a model of the effects of the eddy current on it, 75,76 and mapping the eddy current induced fields directly.…”

Section: Eddy Currentsmentioning

confidence: 99%

Diffusion‐tensor MRI: theory, experimental design and data analysis – a technical review

2002

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This article treats the theoretical underpinnings of diffusion-tensor magnetic resonance imaging (DT-MRI), as well as experimental design and data analysis issues. We review the mathematical model underlying DT-MRI, discuss the quantitative parameters that are derived from the measured effective diffusion tensor, and describe artifacts thet arise in typical DT-MRI acquisitions. We also discuss difficulties in identifying appropriate models to describe water diffusion in heterogeneous tissues, as well as in interpreting experimental data obtained in such issues. Finally, we describe new statistical methods that have been developed to analyse DT-MRI data, and their potential uses in clinical and multi-site studies.

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Section: Eddy Currentsmentioning

confidence: 99%

Diffusion‐tensor MRI: theory, experimental design and data analysis – a technical review

2002

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“…We first applied a non-linear warping correction to every diffusion volume to compensate for residual eddy current distortions (Haselgrove and Moore, 1996). Twelve maps of the apparent diffusion coefficient (ADC) were computed from the eddy current corrected images, and then used to compute the diffusion tensor.…”

Section: Diffusion Tensor Image Processingmentioning

confidence: 99%

Brain macrostructural and microstructural abnormalities in cocaine dependence

Lim

Wozniak

Mueller

et al. 2008

Drug and Alcohol Dependence

143

115

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Rationale-Two previous studies have utilized Diffusion Tensor Imaging (DTI) to examine microstructural integrity in cocaine abuse and found evidence of brain abnormalities in white matter.Objective-Using anatomical magnetic resonance imaging (MRI), DTI, and clinical evaluation, the macrostructural and microstructural correlates of cocaine abuse were investigated.Methods-21 men and women (mean age 42.5, mean 18.9 years of cocaine use) and 21 age/gendermatched controls were included. Fractional anisotropy (FA) was measured in frontal white matter ROIs. Gray and white matter volumes in superior and inferior frontal regions were compared.Results-DTI data revealed that cocaine users had lower FA than controls, specifically in inferior frontal white matter. FA differences were not seen in other areas. Significant volumetric differences were not seen, but both grey and white matter inferior frontal volumes trended toward smaller in the cocaine group. The data suggested that duration of use was associated with decreased grey and white matter volumes. FA and grey matter volume were correlated in cocaine users.Conclusions-Both macrostructural and microstructural abnormalities were seen in a group of cocaine abusers. Length of cocaine use was associated with severity of the brain abnormalities. Future studies of white matter tissue integrity are warranted including examination of the relationship between DTI measures and traditional volumetric measures.

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“…Images are realigned using a combination of intra-modal 49 and cross-modal 2D and 3D affine procedures specially targeted to low-order linear distortions 47 that are characteristic of Eddy currents. 50 The realignment procedures also correct for in-plane and through-plane subject motion. Images are averaged across frames and runs to increase SNR and to partially recover the precision in signal intensity levels lost in the integerization step of MRI reconstruction.…”

Section: Processing Of Dt-mri Data Prior To Tensor and Track Computationmentioning

confidence: 99%

Diffusion tensor fiber tracking of human brain connectivity: aquisition methods, reliability analysis and biological results

et al. 2002

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We present a description, biological results and a reliability analysis for the method of diffusion tensor tracking (DTT) of white matter fiber pathways. In DTT, diffusion-tensor MRI (DT-MRI) data are collected and processed to visualize the line trajectories of fiber bundles within white matter (WM) pathways of living humans. A detailed description of the data acquisition is given. Technical aspects and experimental results are illustrated for the geniculo-calcarine tract with broad projections to visual cortex, occipital and parietal U-fibers, and the temporocalcarine ventral pathway. To better understand sources of error and to optimize the method, accuracy and precision were analyzed by computer simulations. In the simulations, noisy DT-MRI data were computed that would be obtained for a WM pathway having a helical trajectory passing through gray matter. The error vector between the real and ideal track was computed, and random errors accumulated with the square root of track length consistent with a random-walk process. Random error was most dependent on signal-to-noise ratio, followed by number of averages, pathway anisotropy and voxel size, in decreasing order. Systematic error only occurred for a few conditions, and was most dependent on the stepping algorithm, anisotropy of the surrounding tissue, and non-equal voxel dimensions. Both random and systematic errors were typically below the voxel dimension. Other effects such as track rebound and track recovery also depended on experimental conditions. The methods, biological results and error analysis herein may improve the understanding and optimization of DTT for use in various applications in neuroscience and medicine.

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Correction for distortion of echo‐planar images used to calculate the apparent diffusion coefficient

Cited by 298 publications

References 5 publications

Diffusion‐tensor MRI: theory, experimental design and data analysis – a technical review

Diffusion‐tensor MRI: theory, experimental design and data analysis – a technical review

Brain macrostructural and microstructural abnormalities in cocaine dependence

Diffusion tensor fiber tracking of human brain connectivity: aquisition methods, reliability analysis and biological results

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