Related Experiment Video
Updated: Jun 23, 2026
09:55
Troubleshooting and Quality Assurance in Hyperpolarized Xenon Magnetic Resonance Imaging: Tools for High-Quality Image Acquisition
Published on: January 5, 2024
A new distortion model for strong inhomogeneity problems in echo-planar MRI
Marcelo V W Zibetti1, Alvaro R De Pierro
1Federal University of Technology-Paraná (UTFPR), 80230-901 Curitiba, Brazil. marcelozibetti@utfpr.edu.br
IEEE Transactions on Medical Imaging
|May 22, 2009
Summary
This study introduces an improved echo planar imaging (EPI) distortion model to address magnetic field inhomogeneity. The new model significantly reduces geometrical distortions and signal loss in magnetic resonance imaging (MRI).
Area of Science:
- Medical Imaging
- Magnetic Resonance Imaging (MRI)
- Image Reconstruction
Background:
- Fast imaging sequences like echo planar imaging (EPI) are crucial for applications requiring high temporal resolution.
- EPI is highly sensitive to magnetic field inhomogeneity, causing geometrical distortions and signal attenuation.
- Existing distortion models struggle with strong inhomogeneity and discretization artifacts.
Purpose of the Study:
- To propose a novel distortion model for echo planar imaging (EPI) that effectively handles strong magnetic field inhomogeneity.
- To minimize discretization artifacts and signal loss caused by intravoxel dephasing in EPI.
- To evaluate the performance of the new model across various image reconstruction methods.
Main Methods:
- Modification of the discrete distortion model to incorporate intravoxel inhomogeneity effects.
- Implementation of techniques to minimize discretization artifacts.
- Experimental validation using conjugate phase, least squares, and regularized reconstruction methods.
Main Results:
- Significant reduction in geometrical distortions and intensity variations in EPI images.
- Mitigation of signal attenuation in regions with high inhomogeneity.
- Demonstrated improvements in image quality across different reconstruction algorithms.
Conclusions:
- The proposed distortion model offers a substantial improvement for EPI acquisition under strong magnetic field inhomogeneity.
- The model effectively addresses limitations of existing methods, enhancing image fidelity.
- The enhanced model shows robust performance with various reconstruction techniques, making it broadly applicable.
Related Concept Videos
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
01:24Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a noninvasive medical imaging technique based on a phenomenon of nuclear physics discovered in the 1930s, in which matter exposed to magnetic fields and radio waves was found to emit radio signals. In 1970, a physician and researcher named Raymond Damadian noticed that malignant (cancerous) tissue gave off different signals than normal body tissue. He applied for a patent for the first MRI scanning device in clinical use by the early 1980s. The early MRI...
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...