September 17, 2025

Simulation of SAR and B1+ homogeneity change with subject movement using 16ch transceiver coil at 7T

Key Points

Head movement significantly increases SAR levels, which may exceed safety limits during MRI scans.
The study found that both coil tuning and B1+ shim contribute to changes in SAR and B1+ homogeneity.
Electromagnetic simulation analyzed the impacts of head position, coil tuning, and B1+ shim on SAR and B1+ distributions.
Improving estimates of B1+ and SAR changes could enhance safety measures during MRI scanning procedures.

Abstract

Motivation: SAR estimation at UHF is critical. Particularly when subject moves during scan, SAR could be changed significantly, potentially exceeding limit. Goal(s): We investigated how SAR and B1+ homogeneity is changed by head movement, coil tunning/matching(TM) and B1+ shim. Approach: Using EM simulation with human model with 16ch transceiver, B1+ and SAR distribution was estimated for different head positions, coil TM and B1+ shim. Results: Head movement is main contributor to SAR increase; but also suboptimal coil TM and B1+ shim contributing to the variation. Impact: Estimation of B1+ and SAR changes by subject motion would improve scan safety as well as B1+ shim approach.

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Cite This Study

Kim et al. (Tue,) studied this question.

synapsesocial.com/papers/68d4597031b076d99fa5c8c4 https://doi.org/https://doi.org/10.58530/2025/3965

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