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A comprehensive approach for correcting voxel‐wise b‐value errors in diffusion MRI


Lee, Yoojin; Kettinger, Adam O; Wilm, Bertram Jakob; Deichmann, Ralf; Weiskopf, Nikolaus; Lambert, Christian; Pruessmann, Klaas Paul; Nagy, Zoltan (2020). A comprehensive approach for correcting voxel‐wise b‐value errors in diffusion MRI. Magnetic Resonance in Medicine, 83(6):2173-2184.

Abstract

PURPOSE:
In diffusion MRI, the actual b-value played out on the scanner may deviate from the nominal value due to magnetic field imperfections. A simple image-based correction method for this problem is presented.

METHODS:
The apparent diffusion constant (ADC) of a water phantom was measured voxel-wise along 64 diffusion directions at b = 1000 s/mm2 . The true diffusion constant of water was estimated, considering the phantom temperature. A voxel-wise correction factor, providing an effective b-value including any magnetic field deviations, was determined for each diffusion direction by relating the measured ADC to the true diffusion constant. To test the method, the measured b-value map was used to calculate the corrected voxel-wise ADC for additionally acquired diffusion data sets on the same water phantom and data sets acquired on a small water phantom at three different positions. Diffusion tensor was estimated by applying the measured b-value map to phantom and in vivo data sets.

RESULTS:
The b-value-corrected ADC maps of the phantom showed the expected spatial uniformity as well as a marked improvement in consistency across diffusion directions. The b-value correction for the brain data resulted in a 5.8% and 5.5% decrease in mean diffusivity and angular differences of the primary diffusion direction of 2.71° and 0.73° inside gray and white matter, respectively.

CONCLUSION:
The actual b-value deviates significantly from its nominal setting, leading to a spatially variable error in the common diffusion outcome measures. The suggested method measures and corrects these artifacts.

Abstract

PURPOSE:
In diffusion MRI, the actual b-value played out on the scanner may deviate from the nominal value due to magnetic field imperfections. A simple image-based correction method for this problem is presented.

METHODS:
The apparent diffusion constant (ADC) of a water phantom was measured voxel-wise along 64 diffusion directions at b = 1000 s/mm2 . The true diffusion constant of water was estimated, considering the phantom temperature. A voxel-wise correction factor, providing an effective b-value including any magnetic field deviations, was determined for each diffusion direction by relating the measured ADC to the true diffusion constant. To test the method, the measured b-value map was used to calculate the corrected voxel-wise ADC for additionally acquired diffusion data sets on the same water phantom and data sets acquired on a small water phantom at three different positions. Diffusion tensor was estimated by applying the measured b-value map to phantom and in vivo data sets.

RESULTS:
The b-value-corrected ADC maps of the phantom showed the expected spatial uniformity as well as a marked improvement in consistency across diffusion directions. The b-value correction for the brain data resulted in a 5.8% and 5.5% decrease in mean diffusivity and angular differences of the primary diffusion direction of 2.71° and 0.73° inside gray and white matter, respectively.

CONCLUSION:
The actual b-value deviates significantly from its nominal setting, leading to a spatially variable error in the common diffusion outcome measures. The suggested method measures and corrects these artifacts.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:03 Faculty of Economics > Department of Economics
Dewey Decimal Classification:330 Economics
Scopus Subject Areas:Health Sciences > Radiology, Nuclear Medicine and Imaging
Uncontrolled Keywords:Radiology Nuclear Medicine and imaging
Language:English
Date:June 2020
Deposited On:07 Feb 2020 09:06
Last Modified:22 Apr 2020 22:58
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0740-3194
OA Status:Closed
Publisher DOI:https://doi.org/10.1002/mrm.28078
PubMed ID:31840300

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Embargo till: 2020-12-16