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On the role of physiological fluctuations in quantitative gradient echo MRI: implications for GEPCI, QSM, and SWI
Jie Wen1, Anne H Cross2, Dmitriy A Yablonskiy1
1Department of Radiology, Washington University, St. Louis, Missouri, USA.
Purpose:
Physiological fluctuations in biological tissues adversely affect MR images if present during signal acquisition. This problem is especially important for quantitative MRI. The goal of the studies reported in this study was to reduce the contributions of physiological fluctuations in quantitative MRI based on T2* tissue relaxation properties. Specifically, in this study we deal with GEPCI, QSM, and SWI techniques and propose methods allowing for substantial improvement of their results.
Methods:
We used a navigator imbedded in a multi-gradient-echo sequence to record and correct MR signal phase fluctuations at each phase encoding step. All GEPCI, QSM, and SWI images were then reconstructed from a single acquisition. We used a keyhole-type approach to further average out effects of physiological fluctuations. Voxel spread function technique was used to correct for macroscopic field inhomogeneities.
Results:
Brains of normal subjects and subjects with multiple sclerosis were studied. We demonstrated that our used strategies substantially reduced the width of the R2* = 1/T2* distribution within human brains and significantly improved quantification of tissue damage in multiple sclerosis. We also showed improved quality of the SWI and QSM images.
Conclusion:
The strategies used in this study greatly reduced physiologically induced artifacts in GEPCI, QSM, and SWI, improving the reliability of these techniques.
Insights
This study introduces new methods to reduce physiological noise in quantitative MRI, improving image quality for techniques like GEPCI, QSM, and SWI. These advancements enhance the reliability of MRI scans for diagnosing conditions like multiple sclerosis.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Biomedical Engineering
- Neuroimaging
Background:
- Physiological fluctuations during MRI signal acquisition introduce artifacts, particularly impacting quantitative MRI (qMRI) based on T2* relaxation.
- Accurate qMRI is crucial for diagnosing neurological disorders, but motion artifacts hinder precise tissue characterization.
Purpose of the Study:
- To develop and validate methods for reducing physiological fluctuation artifacts in quantitative MRI.
- To improve the accuracy and reliability of Gradient Echo Phase Contrast Imaging (GEPCI), Quantitative Susceptibility Mapping (QSM), and Susceptibility Weighted Imaging (SWI).
Main Methods:
- A navigator embedded in a multi-gradient-echo sequence was used to correct MR signal phase fluctuations.
- Keyhole imaging and voxel spread function techniques were employed to further mitigate artifacts and correct for field inhomogeneities.
- All GEPCI, QSM, and SWI images were reconstructed from a single acquisition.
Main Results:
- The proposed strategies significantly reduced the R2* (1/T2*) distribution width in human brains.
- Quantification of tissue damage in multiple sclerosis patients was substantially improved.
- The quality of SWI and QSM images was demonstrably enhanced.
Conclusions:
- The implemented strategies effectively reduced physiologically induced artifacts in GEPCI, QSM, and SWI.
- These improvements enhance the diagnostic reliability of these quantitative MRI techniques.
- The study provides a robust method for artifact reduction in advanced MRI applications.
