Temperature Measurements in the Vicinity of Human Intracranial EEG Electrodes Exposed to Body-Coil RF for MRI at 1.5T

Hawsawi, Hassan B.; Papadaki, Anastasia; Thornton, John S.; Carmichael, David W.; Lemieux, Louis

doi:10.3389/fnins.2020.00429

Cited by 6 publications

(3 citation statements)

References 28 publications

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“…For instance, standard human MRI's body excitation coils tend to evoke larger SAR than (custom) local transmit coils, which can lead to stronger heating. Careful assessment of induced heating with computer simulations and actual measurements with electrodes taken in solution, artificial cerebrospinal fluid, egg albumin, or a phantom are highly recommended (Hawsawi et al, 2020). Electrode displacement due to the time-varying stimulation current within the static magnetic field is also a concern that needs to be tested as part of the safety assessment approach before involving experimental animals.…”

Section: Safety Risks and Solutionsmentioning

confidence: 99%

Combining Brain Perturbation and Neuroimaging in Non-human Primates

Klink¹,

jean-francois.aubry@espci.fr²,

Ferrera³

et al. 2020

Preprint

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Brain perturbation studies allow detailed causal inferences of behavioral and neural processes. Because the combination of brain perturbation methods and neural measurement techniques is inherently challenging, research in humans has predominantly focused on non-invasive, indirect brain perturbations, or neurological lesions. Non-human primates have been indispensable as a neurobiological system that is highly similar to humans while simultaneously being more experimentally tractable, allowing visualization of the functional and structural impact of systematic brain perturbation. This review considers the state-of-the-art in non-human primate brain perturbation with a focus on approaches that can be combined with neuroimaging. We consider both non-reversible (lesions) and reversible or temporary perturbations such as electrical, pharmacological, optical, optogenetic, chemogenetic, pathway-selective, and ultrasound based interference methods. Method-specific considerations from the research and development community are offered to facilitate research in this field and support further innovations. We conclude by identifying novel avenues for further research and innovation and by highlighting the clinical translational potential of the methods.

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Section: Safety Risks and Solutionsmentioning

confidence: 99%

Combining Brain Perturbation and Neuroimaging in Non-human Primates

Klink¹,

jean-francois.aubry@espci.fr²,

Ferrera³

et al. 2020

Preprint

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“…14 ). Similar to the setup used here, the body coil was also used to test MRI-induced temperature changes in intracranial electrodes 20 and the body coil was used to examine RF safety of EEG gel during MRI 21 . The imaging quality is not altered by the PEDOT polymer electrodes (Fig.…”

Section: Discussionmentioning

confidence: 99%

Physical behavior of PEDOT polymer electrode during magnetic resonance imaging and long-term test in the climate chamber

Camp

Bergeler²,

Seifert

2023

Sci Rep

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The PEDOT polymer electrode is a metal-free electrode, consisting of an acrylate (dental composite) and the conductive polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The electrode is applied as gel onto the skin and cured with blue light for 10–20 s in order to achieve a conductive bond to the skin. The electrodes are used in combination with polymer cables consisting of a textile backbone and PEDOT:PSS. To test this new electrode and cable type under different conditions we designed two stress-tests: highly sensitive temperature recordings within a head phantom during Magnetic Resonance Imaging (MRI) and long-term stability inside a climate chamber with high humidity. To study the physical behavior inside the strong magnetic field (3 Tesla), the PEDOT polymer electrode was attached to an agarose head-phantom inside a magnetic resonance tomograph during an image sequence. MRI-safe temperature sensors were placed nearby in order to measure possible heating effects. In comparison to a metal cable, nearly no rise in temperature could be observed if the electrode was used in combination with a conductive textile cable. Furthermore, the electrode showed stable impedance values inside a climate chamber for 4 consecutive days. These results pave the way for testing the PEDOT polymer electrode as biosignal recording electrode during MRI, especially for cardio MRI and Electroencephalography in combination with functional MRI (EEG–fMRI).

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“…Although deep brain stimulation (DBS) electrode (MRI-conditional for 3 T) and icEEG electrodes from a specific manufacturer (DIXI medical, MRI-conditional for 1.5–3 T) are allowed for MRI under the restrictive guidelines of manufacturers, most commercial icEEG electrodes have yet to be formally approved for MRI ( Ciumas et al, 2014 ; Hawsawi et al, 2017 ). Nevertheless, structural imaging of icEEG electrodes has been well documented in both clinical and research settings without adverse events at 1.5 T ( Davis et al, 1999 ; Carmichael et al, 2007 , 2008 ; Larson et al, 2008 ; Nazzaro et al, 2010 ; Weise et al, 2010 ; Vulliemoz et al, 2011 ; Zrinzo et al, 2011 ; Hawsawi et al, 2017 , 2020 ; Erhardt et al, 2018 ; Hall and Khoo, 2018 ; Yazdani et al, 2021 ). Imaging of DBS electrodes at 3 T has also been documented in 10 patients with a mild temperature increase and concluded to be potentially safe ( Sammartino et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Safety of Simultaneous Intracranial Electroencephalography and Functional Magnetic Resonance Imaging Acquisition Using a 3 Tesla Magnetic Resonance Imaging Scanner

et al. 2022

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BackgroundThe unsurpassed sensitivity of intracranial electroencephalography (icEEG) and the growing interest in understanding human brain networks and ongoing activities in health and disease have make the simultaneous icEEG and functional magnetic resonance imaging acquisition (icEEG-fMRI) an attractive investigation tool. However, safety remains a crucial consideration, particularly due to the impact of the specific characteristics of icEEG and MRI technologies that were safe when used separately but may risk health when combined. Using a clinical 3-T scanner with body transmit and head-receive coils, we assessed the safety and feasibility of our icEEG-fMRI protocol.MethodsUsing platinum and platinum-iridium grid and depth electrodes implanted in a custom-made acrylic-gel phantom, we assessed safety by focusing on three factors. First, we measured radio frequency (RF)-induced heating of the electrodes during fast spin echo (FSE, as a control) and the three sequences in our icEEG-fMRI protocol. Heating was evaluated with electrodes placed orthogonal or parallel to the static magnetic field. Using the configuration with the greatest heating observed, we then measured the total heating induced in our protocol, which is a continuous 70-min icEEG-fMRI session comprising localizer, echo-planar imaging (EPI), and magnetization-prepared rapid gradient-echo sequences. Second, we measured the gradient switching-induced voltage using configurations mimicking electrode implantation in the frontal and temporal lobes. Third, we assessed the gradient switching-induced electrode movement by direct visual detection and image analyses.ResultsOn average, RF-induced local heating on the icEEG electrode contacts tested were greater in the orthogonal than parallel configuration, with a maximum increase of 0.2°C during EPI and 1.9°C during FSE. The total local heating was below the 1°C safety limit across all contacts tested during the 70-min icEEG-fMRI session. The induced voltage was within the 100-mV safety limit regardless of the configuration. No gradient switching-induced electrode displacement was observed.ConclusionWe provide evidence that the additional health risks associated with heating, neuronal stimulation, or device movement are low when acquiring fMRI at 3 T in the presence of clinical icEEG electrodes under the conditions reported in this study. High specific absorption ratio sequences such as FSE should be avoided to prevent potential inadvertent tissue heating.

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Temperature Measurements in the Vicinity of Human Intracranial EEG Electrodes Exposed to Body-Coil RF for MRI at 1.5T

Cited by 6 publications

References 28 publications

Combining Brain Perturbation and Neuroimaging in Non-human Primates

Combining Brain Perturbation and Neuroimaging in Non-human Primates

Physical behavior of PEDOT polymer electrode during magnetic resonance imaging and long-term test in the climate chamber

Evaluating the Safety of Simultaneous Intracranial Electroencephalography and Functional Magnetic Resonance Imaging Acquisition Using a 3 Tesla Magnetic Resonance Imaging Scanner

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