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Distortion correction for diffusion-weighted MRI tractography and fMRI in the temporal lobes

K.V. Embleton, H.A. Haroon, D.M. Morris, M.A. Lambon Ralph, G.J.M. Parker

Human Brain Mapping. 2010;31(10):1570-1587.

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Abstract

Single shot echo-planar imaging (EPI) sequences are currently the most commonly used sequen- ces for diffusion-weighted imaging (DWI) and functional magnetic resonance imaging (fMRI) as they allow relatively high signal to noise with rapid acquisition time. A major drawback of EPI is the substantial geo- metric distortion and signal loss that can occur due to magnetic field inhomogeneities close to air-tissue boundaries. If DWI-based tractography and fMRI are to be applied to these regions, then the distortions must be accurately corrected to achieve meaningful results. We describe robust acquisition and processing methods for correcting such distortions in spin echo (SE) EPI using a variant of the reversed direction k space traversal method with a number of novel additions. We demonstrate that dual direction k space tra- versal with maintained diffusion-encoding gradient strength and direction results in correction of the great majority of eddy current-associated distortions in DWI, in addition to those created by variations in mag- netic susceptibility. We also provide examples to demonstrate that the presence of severe distortions cannot be ignored if meaningful tractography results are desired. The distortion correction routine was applied to SE-EPI fMRI acquisitions and allowed detection of activation in the temporal lobe that had been previously found using PET but not conventional fMRI.

Keyword(s)

diffusion-weighted imaging distortion echo planar imaging tractography magnetic susceptibility fMRI

Bibliographic metadata

Type of resource:
Content type:
Publication type:
Publication form:
Published date:
Journal title:
Volume:
31
Issue:
10
Start page:
1570
End page:
1587
Digital Object Identifier:
10.1002/hbm.20959
Access state:
Active

Institutional metadata

University researcher(s):

Record metadata

Manchester eScholar ID:
uk-ac-man-scw:80978
Created by:
Parker, Geoffrey
Created:
14th May, 2010, 09:15:07
Last modified by:
Parker, Geoffrey
Last modified:
13th January, 2015, 08:16:40

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