RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field Generator

The use of a transfer function (TF) method enables a conservative estimation for radio frequency (RF) safety assessment of active implantable devices (AIMDs). The TF approach can be applied to various scan conditions, patient populations, and device trajectories inside the human body, reducing the c...

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Main Authors: Hongbae Jeong, Joshua W. Guag, Ananda Kumar
Format: Article
Language:English
Published: IEEE 2024-01-01
Series:IEEE Access
Subjects:
Online Access:https://ieeexplore.ieee.org/document/10804130/
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author Hongbae Jeong
Joshua W. Guag
Ananda Kumar
author_facet Hongbae Jeong
Joshua W. Guag
Ananda Kumar
author_sort Hongbae Jeong
collection DOAJ
description The use of a transfer function (TF) method enables a conservative estimation for radio frequency (RF) safety assessment of active implantable devices (AIMDs). The TF approach can be applied to various scan conditions, patient populations, and device trajectories inside the human body, reducing the computational burden of full-wave electromagnetic (EM) simulation. The in vitro TF model validation process is time-consuming, requiring tests in various sample trajectories that collectively exceed eight hours. Here, we demonstrated reducing the burden of the TF approach using a low-power tabletop E-field generator. We measured the TF of the stent via the piecewise excitation method at 128 MHz and validated it by exposing the device under diverse test exposure fields using a tabletop E-field generator that requires less phantom material, lower cost than whole-body coil or MRI scanner, and with reduced experimental safety hazards or shielded room requirements. The TF approach was used to predict radio frequency (RF)-induced power near the stent tip at 128 MHz and predicted values were then compared against measured values. We also used a body transmit coil to compare the conventional in vitro TF model validation approach and tabletop E-field generator. With the tabletop E-field generator, the equivalent absolute normalized error was (<inline-formula> <tex-math notation="LaTeX">$0.37~\pm ~0.31$ </tex-math></inline-formula> dB) compared to the body transmit coil tests (<inline-formula> <tex-math notation="LaTeX">$0.43~\pm ~0.15$ </tex-math></inline-formula> dB), and the required test time decreased from eight to three hours. In summary, we showed how a low-power compact E-field generator can be used for in vitro TF model validation with reduced testing time and cost without using a shielded room.
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spelling doaj-art-162a370ca4a74affb7931da66825c7b92024-12-21T00:00:45ZengIEEEIEEE Access2169-35362024-01-011219194519195410.1109/ACCESS.2024.351897410804130RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field GeneratorHongbae Jeong0https://orcid.org/0000-0003-4908-2070Joshua W. Guag1Ananda Kumar2Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, USAOffice of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, USAOffice of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, USAThe use of a transfer function (TF) method enables a conservative estimation for radio frequency (RF) safety assessment of active implantable devices (AIMDs). The TF approach can be applied to various scan conditions, patient populations, and device trajectories inside the human body, reducing the computational burden of full-wave electromagnetic (EM) simulation. The in vitro TF model validation process is time-consuming, requiring tests in various sample trajectories that collectively exceed eight hours. Here, we demonstrated reducing the burden of the TF approach using a low-power tabletop E-field generator. We measured the TF of the stent via the piecewise excitation method at 128 MHz and validated it by exposing the device under diverse test exposure fields using a tabletop E-field generator that requires less phantom material, lower cost than whole-body coil or MRI scanner, and with reduced experimental safety hazards or shielded room requirements. The TF approach was used to predict radio frequency (RF)-induced power near the stent tip at 128 MHz and predicted values were then compared against measured values. We also used a body transmit coil to compare the conventional in vitro TF model validation approach and tabletop E-field generator. With the tabletop E-field generator, the equivalent absolute normalized error was (<inline-formula> <tex-math notation="LaTeX">$0.37~\pm ~0.31$ </tex-math></inline-formula> dB) compared to the body transmit coil tests (<inline-formula> <tex-math notation="LaTeX">$0.43~\pm ~0.15$ </tex-math></inline-formula> dB), and the required test time decreased from eight to three hours. In summary, we showed how a low-power compact E-field generator can be used for in vitro TF model validation with reduced testing time and cost without using a shielded room.https://ieeexplore.ieee.org/document/10804130/Magnetic resonance imaging (MRI)transfer function model validationMR safetyregulatory science toolsMITS-TTspecific absorption rate (SAR)
spellingShingle Hongbae Jeong
Joshua W. Guag
Ananda Kumar
RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field Generator
IEEE Access
Magnetic resonance imaging (MRI)
transfer function model validation
MR safety
regulatory science tools
MITS-TT
specific absorption rate (SAR)
title RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field Generator
title_full RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field Generator
title_fullStr RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field Generator
title_full_unstemmed RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field Generator
title_short RF-Induced Heating Estimation of a Stent in a 3T MRI Using Transfer Function Approach With a Tabletop E-Field Generator
title_sort rf induced heating estimation of a stent in a 3t mri using transfer function approach with a tabletop e field generator
topic Magnetic resonance imaging (MRI)
transfer function model validation
MR safety
regulatory science tools
MITS-TT
specific absorption rate (SAR)
url https://ieeexplore.ieee.org/document/10804130/
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