A hybrid volume-surface integral equation method for rapid electromagnetic simulations in MRI

TL;DR

This paper introduces a hybrid volume-surface integral equation method that significantly accelerates MRI electromagnetic simulations by efficiently modeling both local and remote conductive elements, enabling rapid and accurate results.

Contribution

The paper presents a novel hybrid VSIE approach combining domain decomposition and advanced algorithms to improve simulation speed and memory efficiency in MRI modeling.

Findings

Achieved at least 23 times faster simulation at 2 mm VIR

Reduced memory usage by 760 times compared to traditional methods

Enabled practical 1 mm isotropic resolution MRI simulations

Abstract

Objective: We developed a hybrid volume surface integral equation (VSIE) method based on domain decomposition to perform fast and accurate magnetic resonance imaging (MRI) simulations that include both remote and local conductive elements. Methods: We separated the conductive surfaces present in MRI setups into two domains and optimized electromagnetic (EM) modeling for each case. Specifically, interactions between the body and EM waves originating from local radiofrequency (RF) coils were modeled with the precorrected fast Fourier transform, whereas the interactions with remote conductive surfaces (RF shield, scanner bore) were modeled with a novel cross tensor train-based algorithm. We compared the hybrid- VSIE with other VSIE methods for realistic MRI simulation setups. Results: The hybrid-VSIE was the only practical method for simulation using 1 mm voxel isotropic resolution (VIR). For 2 mm VIR, our method could be solved at least 23 times faster and required 760 times lower memory than traditional VSIE methods. Conclusion: The hybrid-VSIE demonstrated a marked improvement in terms of convergence times of the numerical EM simulation compared to traditional approaches in multiple realistic MRI scenarios. Significance: The efficiency of the novel hybrid-VSIE method could enable rapid simulations of complex and comprehensive MRI setups.