Reducing RF-Induced Heating Near Implanted Leads Through High-Dielectric Capacitive Bleeding of Current (CBLOC)

Laleh Golestanirad; Leonardo M. Angelone; John Kirsch; Sean Downs; Boris Keil; Giorgio Bonmassar; Lawrence L. Wald

doi:10.1109/TMTT.2018.2885517

Reducing RF-Induced Heating Near Implanted Leads Through High-Dielectric Capacitive Bleeding of Current (CBLOC)

Laleh Golestanirad^*, Leonardo M. Angelone, John Kirsch, Sean Downs, Boris Keil, Giorgio Bonmassar, Lawrence L. Wald

^*Corresponding author for this work

Biomedical Engineering

Research output: Contribution to journal › Article › peer-review

33 Scopus citations

Abstract

Patients with implanted medical devices such as deep brain stimulation or spinal cord stimulation are often unable to receive magnetic resonance imaging (MRI). This is because, once the device is within the radio frequency (RF) field of the MRI scanner, electrically conductive leads act as antenna, amplifying the RF energy deposition in the tissue and causing possible excessive tissue heating. Here, we propose a novel concept in lead design in which 40-cm lead wires are coated with a ∼1.2-mm layer of high dielectric constant material (155 < ϵ_r < 250) embedded in a weakly conductive insulation (σ = 20 S/m). The technique called high-dielectric capacitive bleeding of current (CBLOC) works by forming a distributed capacitance along the lengths of the lead, efficiently dissipating RF energy before it reaches the exposed tip. Measurements during RF exposure at 64 and 123 MHz demonstrated that CBLOC leads generated 20-fold less heating at 1.5 T and 40-fold less heating at 3 T compared to control leads. Numerical simulations of RF exposure at 297 MHz (7 T) predicted a 15-fold reduction in specific absorption rate of RF energy around the tip of CBLOC leads compared to control leads.

Original language	English (US)
Article number	8598958
Pages (from-to)	1265-1273
Number of pages	9
Journal	IEEE Transactions on Microwave Theory and Techniques
Volume	67
Issue number	3
DOIs	https://doi.org/10.1109/TMTT.2018.2885517
State	Published - Mar 2019

Keywords

Electrode leads
MR conditional
RF heating
finite-element method
high field
high-dielectric material
magnetic resonance imaging (MRI)
medical implants
numerical simulations
radio frequency (RF) safety
specific absorption rate (SAR)

ASJC Scopus subject areas

Radiation
Condensed Matter Physics
Electrical and Electronic Engineering

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10.1109/TMTT.2018.2885517

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@article{2834f8daf8b74e8999e748455a900897,

title = "Reducing RF-Induced Heating Near Implanted Leads Through High-Dielectric Capacitive Bleeding of Current (CBLOC)",

abstract = "Patients with implanted medical devices such as deep brain stimulation or spinal cord stimulation are often unable to receive magnetic resonance imaging (MRI). This is because, once the device is within the radio frequency (RF) field of the MRI scanner, electrically conductive leads act as antenna, amplifying the RF energy deposition in the tissue and causing possible excessive tissue heating. Here, we propose a novel concept in lead design in which 40-cm lead wires are coated with a ∼1.2-mm layer of high dielectric constant material (155 < ϵr < 250) embedded in a weakly conductive insulation (σ = 20 S/m). The technique called high-dielectric capacitive bleeding of current (CBLOC) works by forming a distributed capacitance along the lengths of the lead, efficiently dissipating RF energy before it reaches the exposed tip. Measurements during RF exposure at 64 and 123 MHz demonstrated that CBLOC leads generated 20-fold less heating at 1.5 T and 40-fold less heating at 3 T compared to control leads. Numerical simulations of RF exposure at 297 MHz (7 T) predicted a 15-fold reduction in specific absorption rate of RF energy around the tip of CBLOC leads compared to control leads.",

keywords = "Electrode leads, MR conditional, RF heating, finite-element method, high field, high-dielectric material, magnetic resonance imaging (MRI), medical implants, numerical simulations, radio frequency (RF) safety, specific absorption rate (SAR)",

author = "Laleh Golestanirad and Angelone, {Leonardo M.} and John Kirsch and Sean Downs and Boris Keil and Giorgio Bonmassar and Wald, {Lawrence L.}",

note = "Funding Information: Manuscript received July 10, 2018; revised October 1, 2018; accepted November 5, 2018. Date of publication January 1, 2019; date of current version March 5, 2019. This work was supported by the National Institutes of Health (NIH) under Grant R03EB024705. (Giogio Bonmassar and Lawrence L. Wald contributed equally to this work.) (Corresponding author: Laleh Golestanirad.) L. Golestanirad is with the A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA 02129 USA, and also with the Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611 USA (e-mail: laleh.rad1@northwestern.edu). Funding Information: This work was supported by the National Institutes of Health (NIH) under Grant R03EB024705. The mention of commercial products, their sources, or their use in connection with the material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services. Publisher Copyright: {\textcopyright} 2019 IEEE.",

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AU - Golestanirad, Laleh

AU - Angelone, Leonardo M.

AU - Kirsch, John

AU - Downs, Sean

AU - Keil, Boris

AU - Bonmassar, Giorgio

AU - Wald, Lawrence L.

N1 - Funding Information: Manuscript received July 10, 2018; revised October 1, 2018; accepted November 5, 2018. Date of publication January 1, 2019; date of current version March 5, 2019. This work was supported by the National Institutes of Health (NIH) under Grant R03EB024705. (Giogio Bonmassar and Lawrence L. Wald contributed equally to this work.) (Corresponding author: Laleh Golestanirad.) L. Golestanirad is with the A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA 02129 USA, and also with the Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611 USA (e-mail: laleh.rad1@northwestern.edu). Funding Information: This work was supported by the National Institutes of Health (NIH) under Grant R03EB024705. The mention of commercial products, their sources, or their use in connection with the material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services. Publisher Copyright: © 2019 IEEE.

PY - 2019/3

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N2 - Patients with implanted medical devices such as deep brain stimulation or spinal cord stimulation are often unable to receive magnetic resonance imaging (MRI). This is because, once the device is within the radio frequency (RF) field of the MRI scanner, electrically conductive leads act as antenna, amplifying the RF energy deposition in the tissue and causing possible excessive tissue heating. Here, we propose a novel concept in lead design in which 40-cm lead wires are coated with a ∼1.2-mm layer of high dielectric constant material (155 < ϵr < 250) embedded in a weakly conductive insulation (σ = 20 S/m). The technique called high-dielectric capacitive bleeding of current (CBLOC) works by forming a distributed capacitance along the lengths of the lead, efficiently dissipating RF energy before it reaches the exposed tip. Measurements during RF exposure at 64 and 123 MHz demonstrated that CBLOC leads generated 20-fold less heating at 1.5 T and 40-fold less heating at 3 T compared to control leads. Numerical simulations of RF exposure at 297 MHz (7 T) predicted a 15-fold reduction in specific absorption rate of RF energy around the tip of CBLOC leads compared to control leads.

AB - Patients with implanted medical devices such as deep brain stimulation or spinal cord stimulation are often unable to receive magnetic resonance imaging (MRI). This is because, once the device is within the radio frequency (RF) field of the MRI scanner, electrically conductive leads act as antenna, amplifying the RF energy deposition in the tissue and causing possible excessive tissue heating. Here, we propose a novel concept in lead design in which 40-cm lead wires are coated with a ∼1.2-mm layer of high dielectric constant material (155 < ϵr < 250) embedded in a weakly conductive insulation (σ = 20 S/m). The technique called high-dielectric capacitive bleeding of current (CBLOC) works by forming a distributed capacitance along the lengths of the lead, efficiently dissipating RF energy before it reaches the exposed tip. Measurements during RF exposure at 64 and 123 MHz demonstrated that CBLOC leads generated 20-fold less heating at 1.5 T and 40-fold less heating at 3 T compared to control leads. Numerical simulations of RF exposure at 297 MHz (7 T) predicted a 15-fold reduction in specific absorption rate of RF energy around the tip of CBLOC leads compared to control leads.

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KW - medical implants

KW - numerical simulations

KW - radio frequency (RF) safety

KW - specific absorption rate (SAR)

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Reducing RF-Induced Heating Near Implanted Leads Through High-Dielectric Capacitive Bleeding of Current (CBLOC)

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