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B0-informed variable density trajectory design for enhanced correction of off-resonance effects in parallel
Rainer Schneider1, Dieter Ritter, Jens Haueisen
1MR Application Development, Siemens Healthcare, Erlangen, Germany; Institute of Biomedical Engineering and Informatics, Ilmenau University of Technology, Ilmenau, Germany.
Magnetic Resonance in Medicine
|May 30, 2013
Summary
This study introduces a new trajectory design for magnetic resonance imaging (MRI) radio-frequency (RF) pulses, significantly improving excitation performance and reducing RF power. This advancement enhances parallel transmission capabilities and off-resonance correction in MRI scans.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Radio-Frequency (RF) Pulse Design
- Parallel Transmission Technology
Background:
- B1 and B0 inhomogeneity affects MRI quality.
- Parallel transmission aims to improve RF pulse performance.
- Existing methods struggle with off-resonance correction and power efficiency.
Purpose of the Study:
- Improve B1/B0 inhomogeneity mitigation in parallel transmission.
- Decrease RF pulse power consumption.
- Enhance off-resonance correction for spoke-trajectory RF pulses.
Main Methods:
- Defined target magnetization patterns for optimal excitation resolution.
- Introduced a novel variable-density trajectory design to mitigate B0 phase errors.
- Conducted simulations (echo-planar and spiral 2DRF) and validated in vivo experiments on a 3T MRI system.
Main Results:
- Proper target pattern definition can necessitate spatial filtering, impacting performance and power.
- The new trajectory design significantly improves off-resonance compensation.
- Achieved 43% less RMSE and 79% less RF power for spoke-based pulses.
Conclusions:
- Proposed methods enhance excitation performance (homogeneity, acceleration) and reduce RF power.
- Single-channel transmit RF pulse performance can also be improved.
- Offers a more efficient and effective approach to RF pulse design in MRI.
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