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Chen YI, Ay I, Marturano F, Fuller P, Millan H, Bonmassar G. A Polymer Thick Film on an Organic Substrate Grid Electrode and an Open-Source Recording System for UHF MRI: An Imaging Study. SENSORS (BASEL, SWITZERLAND) 2024; 24:5214. [PMID: 39204909 PMCID: PMC11359886 DOI: 10.3390/s24165214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 07/26/2024] [Accepted: 07/31/2024] [Indexed: 09/04/2024]
Abstract
Electrocorticography (ECoG) is a critical tool in preclinical neuroscience research for studying global network activity. However, integrating ECoG with functional magnetic resonance imaging (fMRI) has posed challenges, due to metal electrode interference with imaging quality and heating around the metallic electrodes. Here, we introduce recent advancements in ECoG grid development that utilize a polymer-thick film on an organic substrate (PTFOS). PTFOS offers notable advantages over traditional ECoG grids. Firstly, it significantly reduces imaging artifacts, ensuring minimal interference with MR image quality when overlaying brain tissue with PTFOS grids. Secondly, during a 30-min fMRI acquisition, the temperature increase associated with PTFOS grids is remarkably low, measuring only 0.4 °C. These findings suggest that utilizing ECoG with PTFOS grids has the potential to enhance the safety and efficacy of neurosurgical procedures. By providing clearer imaging results and mitigating risk factors such as excessive heating during MRI scans, PTFOS-based ECoG grids represent a promising advancement in neurosurgical technology. Furthermore, we describe a cutting-edge open-source system designed for simultaneous electrophysiology and fMRI. This system stands out due to its exceptionally low input noise levels (<0.6 V peak-to-peak), robust electromagnetic compatibility (it is suitable for use in MRI environments up to 9.4 teslas), and the inclusion of user-programmable real-time signal-processing capabilities. The open-platform software is a key feature, enabling researchers to swiftly implement and customize real-time signal-processing algorithms to meet specific experimental needs. This innovative system has been successfully utilized in several rodent EEG/fMRI studies, particularly at magnetic field strengths of 4.7 and 9.4 teslas, focusing on the somatosensory system. These studies have allowed for detailed observation of neural activity and responses within this sensory system, providing insights that are critical for advancing our understanding of neurophysiological processes. The versatility and high performance of our system make it an invaluable tool for researchers aiming to integrate and analyze complex datasets from advanced imaging and electrophysiological recordings, ultimately enhancing the depth and scope of neuroscience research.
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Affiliation(s)
- Yinching Iris Chen
- AA. Martinos Center Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; (Y.I.C.); (I.A.); (F.M.); (H.M.)
| | - Ilknur Ay
- AA. Martinos Center Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; (Y.I.C.); (I.A.); (F.M.); (H.M.)
| | - Francesca Marturano
- AA. Martinos Center Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; (Y.I.C.); (I.A.); (F.M.); (H.M.)
| | - Peter Fuller
- PLF Consulting, 258 Harvard Street #324, Brookline, MA 02446-2904, USA;
| | - Hernan Millan
- AA. Martinos Center Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; (Y.I.C.); (I.A.); (F.M.); (H.M.)
- PLF Consulting, 258 Harvard Street #324, Brookline, MA 02446-2904, USA;
| | - Giorgio Bonmassar
- AA. Martinos Center Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; (Y.I.C.); (I.A.); (F.M.); (H.M.)
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Jeong H, Ntolkeras G, Warbrick T, Jaschke M, Gupta R, Lev MH, Peters JM, Grant PE, Bonmassar G. Aluminum Thin Film Nanostructure Traces in Pediatric EEG Net for MRI and CT Artifact Reduction. SENSORS (BASEL, SWITZERLAND) 2023; 23:3633. [PMID: 37050693 PMCID: PMC10098641 DOI: 10.3390/s23073633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/24/2023] [Accepted: 03/28/2023] [Indexed: 06/19/2023]
Abstract
Magnetic resonance imaging (MRI) and continuous electroencephalogram (EEG) monitoring are essential in the clinical management of neonatal seizures. EEG electrodes, however, can significantly degrade the image quality of both MRI and CT due to substantial metallic artifacts and distortions. Thus, we developed a novel thin film trace EEG net ("NeoNet") for improved MRI and CT image quality without compromising the EEG signal quality. The aluminum thin film traces were fabricated with an ultra-high-aspect ratio (up to 17,000:1, with dimensions 30 nm × 50.8 cm × 100 µm), resulting in a low density for reducing CT artifacts and a low conductivity for reducing MRI artifacts. We also used numerical simulation to investigate the effects of EEG nets on the B1 transmit field distortion in 3 T MRI. Specifically, the simulations predicted a 65% and 138% B1 transmit field distortion higher for the commercially available copper-based EEG net ("CuNet", with and without current limiting resistors, respectively) than with NeoNet. Additionally, two board-certified neuroradiologists, blinded to the presence or absence of NeoNet, compared the image quality of MRI images obtained in an adult and two children with and without the NeoNet device and found no significant difference in the degree of artifact or image distortion. Additionally, the use of NeoNet did not cause either: (i) CT scan artifacts or (ii) impact the quality of EEG recording. Finally, MRI safety testing confirmed a maximum temperature rise associated with the NeoNet device in a child head-phantom to be 0.84 °C after 30 min of high-power scanning, which is within the acceptance criteria for the temperature for 1 h of normal operating mode scanning as per the FDA guidelines. Therefore, the proposed NeoNet device has the potential to allow for concurrent EEG acquisition and MRI or CT scanning without significant image artifacts, facilitating clinical care and EEG/fMRI pediatric research.
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Affiliation(s)
- Hongbae Jeong
- AA. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Georgios Ntolkeras
- Department of Newborn Medicine, Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Baystate Medical Center, University of Massachusetts Medical School, Springfield, MA 01605, USA
| | | | | | - Rajiv Gupta
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Michael H. Lev
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Jurriaan M. Peters
- Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Patricia Ellen Grant
- Department of Newborn Medicine, Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Giorgio Bonmassar
- AA. Martinos Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
- Department of Newborn Medicine, Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Boston, MA 02115, USA
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Yan T, Kameda S, Suzuki K, Kaiju T, Inoue M, Suzuki T, Hirata M. Minimal Tissue Reaction after Chronic Subdural Electrode Implantation for Fully Implantable Brain-Machine Interfaces. SENSORS 2020; 21:s21010178. [PMID: 33383864 PMCID: PMC7795822 DOI: 10.3390/s21010178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 12/12/2020] [Accepted: 12/25/2020] [Indexed: 11/16/2022]
Abstract
There is a growing interest in the use of electrocorticographic (ECoG) signals in brain–machine interfaces (BMIs). However, there is still a lack of studies involving the long-term evaluation of the tissue response related to electrode implantation. Here, we investigated biocompatibility, including chronic tissue response to subdural electrodes and a fully implantable wireless BMI device. We implanted a half-sized fully implantable device with subdural electrodes in six beagles for 6 months. Histological analysis of the surrounding tissues, including the dural membrane and cortices, was performed to evaluate the effects of chronic implantation. Our results showed no adverse events, including infectious signs, throughout the 6-month implantation period. Thick connective tissue proliferation was found in the surrounding tissues in the epidural space and subcutaneous space. Quantitative measures of subdural reactive tissues showed minimal encapsulation between the electrodes and the underlying cortex. Immunohistochemical evaluation showed no significant difference in the cell densities of neurons, astrocytes, and microglia between the implanted sites and contralateral sites. In conclusion, we established a beagle model to evaluate cortical implantable devices. We confirmed that a fully implantable wireless device and subdural electrodes could be stably maintained with sufficient biocompatibility in vivo.
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Affiliation(s)
- Tianfang Yan
- Department of Neurological Diagnosis and Restoration, Osaka University Graduate School of Medicine, Suita 565-0871, Japan; (T.Y.); (S.K.)
| | - Seiji Kameda
- Department of Neurological Diagnosis and Restoration, Osaka University Graduate School of Medicine, Suita 565-0871, Japan; (T.Y.); (S.K.)
- Global Center for Medical Engineering and Informatics, Osaka University, Suita 565-0871, Japan
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita 565-0871, Japan
| | - Katsuyoshi Suzuki
- Ogino Memorial Laboratory, Nihon Kohden Corporation, Tokorozawa 359-0037, Japan;
| | - Taro Kaiju
- Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita 565-0871, Japan; (T.K.); (M.I.); (T.S.)
| | - Masato Inoue
- Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita 565-0871, Japan; (T.K.); (M.I.); (T.S.)
| | - Takafumi Suzuki
- Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita 565-0871, Japan; (T.K.); (M.I.); (T.S.)
| | - Masayuki Hirata
- Department of Neurological Diagnosis and Restoration, Osaka University Graduate School of Medicine, Suita 565-0871, Japan; (T.Y.); (S.K.)
- Global Center for Medical Engineering and Informatics, Osaka University, Suita 565-0871, Japan
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita 565-0871, Japan
- Correspondence:
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Li SJ, Lo YC, Lai HY, Lin SH, Lin HC, Lin TC, Chang CW, Chen TC, Chin-Jung Hsieh C, Yang SH, Chiu FM, Kuo CH, Chen YY. Uncovering the Modulatory Interactions of Brain Networks in Cognition with Central Thalamic Deep Brain Stimulation Using Functional Magnetic Resonance Imaging. Neuroscience 2020; 440:65-84. [DOI: 10.1016/j.neuroscience.2020.05.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 05/05/2020] [Accepted: 05/12/2020] [Indexed: 01/04/2023]
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Erhardt JB, Lottner T, Martinez J, Özen AC, Schuettler M, Stieglitz T, Ennis DB, Bock M. It's the little things: On the complexity of planar electrode heating in MRI. Neuroimage 2019; 195:272-284. [PMID: 30935911 DOI: 10.1016/j.neuroimage.2019.03.061] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 03/07/2019] [Accepted: 03/26/2019] [Indexed: 10/27/2022] Open
Abstract
Neurological disorders are increasingly analysed and treated with implantable electrodes, and patients with such electrodes are studied with MRI despite the risk of radio-frequency (RF) induced heating during the MRI exam. Recent clinical research suggests that electrodes with smaller diameters of the electrical interface between implant and tissue are beneficial; however, the influence of this electrode contact diameter on RF-induced heating has not been investigated. In this work, electrode contact diameters between 0.3 and 4 mm of implantable electrodes appropriate for stimulation and electrocorticography were evaluated in a 1.5 T MRI system. In situ temperature measurements adapted from the ASTM standard test method were performed and complemented by simulations of the specific absorption rate (SAR) to assess local SAR values, temperature increase and the distribution of dissipated power. Measurements showed temperature changes between 0.8 K and 53 K for different electrode contact diameters, which is well above the legal limit of 1 K. Systematic errors in the temperature measurements are to be expected, as the temperature sensors may disturb the heating pattern near small electrodes. Compared to large electrodes, simulations suggest that small electrodes are subject to less dissipated power, but more localized power density. Thus, smaller electrodes might be classified as safe in current certification procedures but may be more likely to burn adjacent tissue. To assess these local heating phenomena, smaller temperature sensors or new non-invasive temperature sensing methods are needed.
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Affiliation(s)
- Johannes B Erhardt
- Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg, Germany; Department of Radiology, University of California, Los Angeles, CA, USA; BrainLinks-BrainTools, Freiburg, Germany
| | - Thomas Lottner
- Department of Radiology - Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jessica Martinez
- Department of Radiology, University of California, Los Angeles, CA, USA; Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Ali C Özen
- Department of Radiology - Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany; German Cancer Consortium Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | - Thomas Stieglitz
- Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg, Germany; Bernstein Center Freiburg, Freiburg, Germany; BrainLinks-BrainTools, Freiburg, Germany
| | - Daniel B Ennis
- Department of Radiology, Stanford University, Stanford, CA, USA
| | - Michael Bock
- Department of Radiology - Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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Iacono MI, Atefi SR, Mainardi L, Walker HC, Angelone LM, Bonmassar G. A Study on the Feasibility of the Deep Brain Stimulation (DBS) Electrode Localization Based on Scalp Electric Potential Recordings. Front Physiol 2019; 9:1788. [PMID: 30662407 PMCID: PMC6328462 DOI: 10.3389/fphys.2018.01788] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 11/28/2018] [Indexed: 11/13/2022] Open
Abstract
Deep Brain Stimulation (DBS) is an effective therapy for patients disabling motor symptoms from Parkinson's disease, essential tremor, and other motor disorders. Precise, individualized placement of DBS electrodes is a key contributor to clinical outcomes following surgery. Electroencephalography (EEG) is widely used to identify the sources of intracerebral signals from the potential on the scalp. EEG is portable, non-invasive, low-cost, and it could be easily integrated into the intraoperative or ambulatory environment for localization of either the DBS electrode or evoked potentials triggered by stimulation itself. In this work, we studied with numerical simulations the principle of extracting the DBS electrical pulse from the patient's EEG - which normally constitutes an artifact - and localizing the source of the artifact (i.e., the DBS electrodes) using EEG localization methods. A high-resolution electromagnetic head model was used to simulate the EEG potential at the scalp generated by the DBS pulse artifact. The potential distribution on the scalp was then sampled at the 256 electrode locations of a high-density EEG Net. The electric potential was modeled by a dipole source created by a given pair of active DBS electrodes. The dynamic Statistical Parametric Maps (dSPM) algorithm was used to solve the EEG inverse problem, and it allowed localization of the position of the stimulus dipole in three DBS electrode bipolar configurations with a maximum error of 1.5 cm. To assess the accuracy of the computational model, the results of the simulation were compared with the electric artifact amplitudes over 16 EEG electrodes measured in five patients. EEG artifacts measured in patients confirmed that simulated data are commensurate to patients' data (0 ± 6.6 μV). While we acknowledge that further work is necessary to achieve a higher accuracy needed for surgical navigation, the results presented in this study are proposed as the first step toward a validated computational framework that could be used for non-invasive localization not only of the DBS system but also brain rhythms triggered by stimulation at both proximal and distal sites in the human central nervous system.
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Affiliation(s)
- Maria Ida Iacono
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States.,Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Seyed Reza Atefi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Luca Mainardi
- Bioengineering Department, Politecnico di Milano, Milan, Italy
| | - Harrison C Walker
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, United States.,Division of Movement Disorders, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Leonardo M Angelone
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Giorgio Bonmassar
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
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Erhardt JB, Fuhrer E, Gruschke OG, Leupold J, Wapler MC, Hennig J, Stieglitz T, Korvink JG. Should patients with brain implants undergo MRI? J Neural Eng 2018. [DOI: 10.1088/1741-2552/aab4e4] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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