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Cardiac Magnetic Resonance Imaging at 7 Tesla
Published on: January 6, 2019
Ultra fast electromagnetic field computations for RF multi-transmit techniques in high field MRI
Bob van den Bergen1, Christiaan C Stolk, Jan Bouwe van den Berg
1Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands. B.vandenBergen@UMCUtrecht.nl
Physics in Medicine and Biology
|February 3, 2009
Summary
A novel, rapid computational method accurately calculates MRI electromagnetic fields. This approach enhances multi-transmit applications by enabling real-time control of electric fields and specific absorption rate (SAR), reducing SAR by over 38%.
Area of Science:
- Medical Imaging
- Computational Electromagnetics
- Magnetic Resonance Imaging (MRI)
Background:
- Accurate calculation of electromagnetic fields is crucial for Magnetic Resonance Imaging (MRI) safety and efficacy.
- Existing methods like Finite-Difference Time-Domain (FDTD) simulations are computationally intensive.
- The need for faster, versatile methods for real-time electromagnetic field control in advanced MRI applications is growing.
Purpose of the Study:
- To present a new, highly efficient computational approach for calculating MRI electromagnetic excitation fields.
- To validate the method's accuracy against established techniques and experimental measurements.
- To explore its potential for real-time control in multi-transmit MRI and radiofrequency (RF) shimming.
Main Methods:
- The calculation domain is partitioned into homogeneous regions, with general solutions derived using basis functions.
- Boundary conditions are enforced to obtain a unique electromagnetic field solution.
- The method combines analytical speed with full-wave simulation versatility, validated against FDTD and 3T measurements.
Main Results:
- The developed method demonstrates high computational speed and accuracy, comparable to FDTD simulations and 3T measurements.
- Validation in the pelvic region at 3T and 7T confirmed the method's reliability.
- RF shimming simulations at 7T showed successful homogenization of the magnetic excitation field and significant SAR reduction (>38%).
Conclusions:
- This fast and accurate electromagnetic field calculation method offers significant potential for multi-transmit MRI applications.
- It enables on-line control of global and local electric fields and specific absorption rate (SAR) within the patient.
- The technique facilitates improved RF shimming, leading to enhanced field homogeneity and reduced SAR.
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