RF-induced heating in tissue near bilateral DBS implants during MRI at 1.5 T and 3T: The role of surgical lead management

Laleh Golestani Rad, John Kirsch, Giorgio Bonmassar, Sean Downs, Behzad Elahi, Alastair Martin, Maria Ida Iacono, Leonardo M. Angelone, Boris Keil, Lawrence L. Wald, Julie Pilitsis

Research output: Contribution to journalArticle

Abstract

Access to MRI is limited for patients with deep brain stimulation (DBS) implants due to safety hazards, including radiofrequency (RF) heating of tissue surrounding the leads. Computational models provide an exquisite tool to explore the multi-variate problem of RF heating and help better understand the interaction of electromagnetic fields and biological tissues. This paper presents a computational approach to assess RF-induced heating, in terms of specific absorption rate (SAR) in the tissue, around the tip of bilateral DBS leads during MRI at 64MHz/1.5 T and 127 MHz/3T. Patient-specific realistic lead models were constructed from post-operative CT images of nine patients operated for sub-thalamic nucleus DBS. Finite element method was applied to calculate the SAR at the tip of left and right DBS contact electrodes. Both transmit head coils and transmit body coils were analyzed. We found a substantial difference between the SAR and temperature rise at the tip of right and left DBS leads, with the lead contralateral to the implanted pulse generator (IPG) exhibiting up to 7 times higher SAR in simulations, and up to 10 times higher temperature rise during measurements. The orientation of incident electric field with respect to lead trajectories was explored and a metric to predict local SAR amplification was introduced. Modification of the lead trajectory was shown to substantially reduce the heating in phantom experiments using both conductive wires and commercially available DBS leads. Finally, the surgical feasibility of implementing the modified trajectories was demonstrated in a patient operated for bilateral DBS.

LanguageEnglish (US)
Pages566-576
Number of pages11
JournalNeuroimage
Volume184
DOIs
StatePublished - Jan 1 2019

Fingerprint

Deep Brain Stimulation
Heating
Thalamic Nuclei
Electromagnetic Fields
Temperature
Lead
Electrodes
Head
Safety

Keywords

  • Computational modeling and simulations
  • Deep brain stimulation (DBS)
  • Finite element method (FEM)
  • Magnetic resonance imaging (MRI)
  • Medical implants
  • MRI safety
  • Neuromodulation
  • Neurostimulation
  • Specific absorption rate (SAR)

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience

Cite this

Golestani Rad, Laleh ; Kirsch, John ; Bonmassar, Giorgio ; Downs, Sean ; Elahi, Behzad ; Martin, Alastair ; Iacono, Maria Ida ; Angelone, Leonardo M. ; Keil, Boris ; Wald, Lawrence L. ; Pilitsis, Julie. / RF-induced heating in tissue near bilateral DBS implants during MRI at 1.5 T and 3T : The role of surgical lead management. In: Neuroimage. 2019 ; Vol. 184. pp. 566-576.
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abstract = "Access to MRI is limited for patients with deep brain stimulation (DBS) implants due to safety hazards, including radiofrequency (RF) heating of tissue surrounding the leads. Computational models provide an exquisite tool to explore the multi-variate problem of RF heating and help better understand the interaction of electromagnetic fields and biological tissues. This paper presents a computational approach to assess RF-induced heating, in terms of specific absorption rate (SAR) in the tissue, around the tip of bilateral DBS leads during MRI at 64MHz/1.5 T and 127 MHz/3T. Patient-specific realistic lead models were constructed from post-operative CT images of nine patients operated for sub-thalamic nucleus DBS. Finite element method was applied to calculate the SAR at the tip of left and right DBS contact electrodes. Both transmit head coils and transmit body coils were analyzed. We found a substantial difference between the SAR and temperature rise at the tip of right and left DBS leads, with the lead contralateral to the implanted pulse generator (IPG) exhibiting up to 7 times higher SAR in simulations, and up to 10 times higher temperature rise during measurements. The orientation of incident electric field with respect to lead trajectories was explored and a metric to predict local SAR amplification was introduced. Modification of the lead trajectory was shown to substantially reduce the heating in phantom experiments using both conductive wires and commercially available DBS leads. Finally, the surgical feasibility of implementing the modified trajectories was demonstrated in a patient operated for bilateral DBS.",
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Golestani Rad, L, Kirsch, J, Bonmassar, G, Downs, S, Elahi, B, Martin, A, Iacono, MI, Angelone, LM, Keil, B, Wald, LL & Pilitsis, J 2019, 'RF-induced heating in tissue near bilateral DBS implants during MRI at 1.5 T and 3T: The role of surgical lead management' Neuroimage, vol. 184, pp. 566-576. https://doi.org/10.1016/j.neuroimage.2018.09.034

RF-induced heating in tissue near bilateral DBS implants during MRI at 1.5 T and 3T : The role of surgical lead management. / Golestani Rad, Laleh; Kirsch, John; Bonmassar, Giorgio; Downs, Sean; Elahi, Behzad; Martin, Alastair; Iacono, Maria Ida; Angelone, Leonardo M.; Keil, Boris; Wald, Lawrence L.; Pilitsis, Julie.

In: Neuroimage, Vol. 184, 01.01.2019, p. 566-576.

Research output: Contribution to journalArticle

TY - JOUR

T1 - RF-induced heating in tissue near bilateral DBS implants during MRI at 1.5 T and 3T

T2 - NeuroImage

AU - Golestani Rad, Laleh

AU - Kirsch, John

AU - Bonmassar, Giorgio

AU - Downs, Sean

AU - Elahi, Behzad

AU - Martin, Alastair

AU - Iacono, Maria Ida

AU - Angelone, Leonardo M.

AU - Keil, Boris

AU - Wald, Lawrence L.

AU - Pilitsis, Julie

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Access to MRI is limited for patients with deep brain stimulation (DBS) implants due to safety hazards, including radiofrequency (RF) heating of tissue surrounding the leads. Computational models provide an exquisite tool to explore the multi-variate problem of RF heating and help better understand the interaction of electromagnetic fields and biological tissues. This paper presents a computational approach to assess RF-induced heating, in terms of specific absorption rate (SAR) in the tissue, around the tip of bilateral DBS leads during MRI at 64MHz/1.5 T and 127 MHz/3T. Patient-specific realistic lead models were constructed from post-operative CT images of nine patients operated for sub-thalamic nucleus DBS. Finite element method was applied to calculate the SAR at the tip of left and right DBS contact electrodes. Both transmit head coils and transmit body coils were analyzed. We found a substantial difference between the SAR and temperature rise at the tip of right and left DBS leads, with the lead contralateral to the implanted pulse generator (IPG) exhibiting up to 7 times higher SAR in simulations, and up to 10 times higher temperature rise during measurements. The orientation of incident electric field with respect to lead trajectories was explored and a metric to predict local SAR amplification was introduced. Modification of the lead trajectory was shown to substantially reduce the heating in phantom experiments using both conductive wires and commercially available DBS leads. Finally, the surgical feasibility of implementing the modified trajectories was demonstrated in a patient operated for bilateral DBS.

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KW - Computational modeling and simulations

KW - Deep brain stimulation (DBS)

KW - Finite element method (FEM)

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KW - Medical implants

KW - MRI safety

KW - Neuromodulation

KW - Neurostimulation

KW - Specific absorption rate (SAR)

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