Improving robustness and reliability of phase-sensitive fMRI analysis using temporal off-resonance alignment of single-echo timeseries (TOAST)

Echo Planar Imaging (EPI), often utilized in functional MRI (fMRI) experiments, is well known for its vulnerability to inconsistencies in the static magnetic field (B0). Correction for these field inhomogeneities usually involves measuring the magnetic field at a single time point, and using this st...

Full description

Saved in:
Bibliographic Details
Published in:NeuroImage (Orlando, Fla.) Fla.), 2009-02, Vol.44 (3), p.742-752
Main Authors: Hahn, Andrew D., Nencka, Andrew S., Rowe, Daniel B.
Format: Article
Language:English
Subjects:
Acquisitions & mergers
Algorithms
Brain - anatomy & histology
Brain - physiology
Brain Mapping - methods
Echo-Planar Imaging - instrumentation
Echo-Planar Imaging - methods
Evoked Potentials - physiology
Humans
Image Enhancement - methods
Image Interpretation, Computer-Assisted - methods
Magnetic fields
Magnetic Resonance Imaging - instrumentation
Magnetic Resonance Imaging - methods
Methods
Noise
Reproducibility of Results
Sensitivity and Specificity
Time series
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Echo Planar Imaging (EPI), often utilized in functional MRI (fMRI) experiments, is well known for its vulnerability to inconsistencies in the static magnetic field (B0). Correction for these field inhomogeneities usually involves measuring the magnetic field at a single time point, and using this static information to correct a series of images collected over the course of one or multiple experiments. However, common phenomena, such as respiration and motion, change the characteristics of the B0 field homogeneity in a time-dependent and often unpredictable manner, rendering previous field measurements invalid. The effects of these changes are particularly large in the image phase, due to its direct and sensitive relationship to the magnetic field, and methods utilizing complex information can suffer enormously. This dependence can be exploited to estimate the temporal dynamics of the B0 field. Use of this information to correct fMRI data can provide more effective motion correction, reduce temporal “noise,” and can substantially restore statistically significant power to complex fMRI data analysis. All of the necessary information is embedded in complex EPI images, and results indicate this is a robust way to improve the quality of fMRI data, especially when used with complex analysis.
ISSN:1053-8119
1095-9572
DOI:10.1016/j.neuroimage.2008.10.001