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Bottauscio O, Arduino A, Chiampi M, Zilberti L. Simplified modeling of implanted medical devices with metallic filamentary closed loops exposed to low or medium frequency magnetic fields. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 229:107316. [PMID: 36566651 DOI: 10.1016/j.cmpb.2022.107316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 12/12/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND AND OBJECTIVES Electric currents are induced in implanted medical devices with metallic filamentary closed loops (e.g., fixation grids, stents) when exposed to time varying magnetic fields, as those generated during certain diagnostic and therapeutic biomedical treatments. A simplified methodology to efficiently compute these currents, to estimate the altered electromagnetic field distribution in the biological tissues and to assess the consequent biological effects is proposed for low or medium frequency fields. METHODS The proposed methodology is based on decoupling the handling of the filamentary wire and the anatomical body. To do this, a circuital solution is adopted to study the metallic filamentary implant and this solution is inserted in the electromagnetic field solution involving the biological tissues. The Joule losses computed in the implant are then used as a forcing term for the thermal problem defined by the bioheat Pennes' equation. The methodology is validated against a model problem, where a reference solution is available. RESULTS The proposed simplified methodology is proved to be in good agreement with solutions provided by alternative approaches. In particular, errors in the amplitude of the currents induced in the wires result to be always lower than 3%. After the validation, the methodology is applied to check the interactions between the magnetic field generated by different biomedical devices and a skull grid, which represents a complex filamentary wire implant. CONCLUSIONS The proposed simplified methodology, suitable to be applied to closed loop wires in the low to intermediate frequency range, is found to be sufficiently accurate and easy to apply in realistic exposure scenarios. This modeling tool allows analyzing different types of small implants, from coronary and biliary duct stents to orthopedic grids, under a variety of exposure scenarios.
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Affiliation(s)
- Oriano Bottauscio
- Istituto Nazionale di Ricerca Metrologica (INRiM), Strada Delle Cacce 91, 10135 Torino, Italy.
| | - Alessandro Arduino
- Istituto Nazionale di Ricerca Metrologica (INRiM), Strada Delle Cacce 91, 10135 Torino, Italy
| | - Mario Chiampi
- Istituto Nazionale di Ricerca Metrologica (INRiM), Strada Delle Cacce 91, 10135 Torino, Italy
| | - Luca Zilberti
- Istituto Nazionale di Ricerca Metrologica (INRiM), Strada Delle Cacce 91, 10135 Torino, Italy
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Acerbo E, Jegou A, Luff C, Dzialecka P, Botzanowski B, Missey F, Ngom I, Lagarde S, Bartolomei F, Cassara A, Neufeld E, Jirsa V, Carron R, Grossman N, Williamson A. Focal non-invasive deep-brain stimulation with temporal interference for the suppression of epileptic biomarkers. Front Neurosci 2022; 16:945221. [PMID: 36061593 PMCID: PMC9431367 DOI: 10.3389/fnins.2022.945221] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 07/12/2022] [Indexed: 11/15/2022] Open
Abstract
Introduction Neurostimulation applied from deep brain stimulation (DBS) electrodes is an effective therapeutic intervention in patients suffering from intractable drug-resistant epilepsy when resective surgery is contraindicated or failed. Inhibitory DBS to suppress seizures and associated epileptogenic biomarkers could be performed with high-frequency stimulation (HFS), typically between 100 and 165 Hz, to various deep-seated targets, such as the Mesio-temporal lobe (MTL), which leads to changes in brain rhythms, specifically in the hippocampus. The most prominent alterations concern high-frequency oscillations (HFOs), namely an increase in ripples, a reduction in pathological Fast Ripples (FRs), and a decrease in pathological interictal epileptiform discharges (IEDs). Materials and methods In the current study, we use Temporal Interference (TI) stimulation to provide a non-invasive DBS (130 Hz) of the MTL, specifically the hippocampus, in both mouse models of epilepsy, and scale the method using human cadavers to demonstrate the potential efficacy in human patients. Simulations for both mice and human heads were performed to calculate the best coordinates to reach the hippocampus. Results This non-invasive DBS increases physiological ripples, and decreases the number of FRs and IEDs in a mouse model of epilepsy. Similarly, we show the inability of 130 Hz transcranial current stimulation (TCS) to achieve similar results. We therefore further demonstrate the translatability to human subjects via measurements of the TI stimulation vs. TCS in human cadavers. Results show a better penetration of TI fields into the human hippocampus as compared with TCS. Significance These results constitute the first proof of the feasibility and efficiency of TI to stimulate at depth an area without impacting the surrounding tissue. The data tend to show the sufficiently focal character of the induced effects and suggest promising therapeutic applications in epilepsy.
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Affiliation(s)
- Emma Acerbo
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Aude Jegou
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Charlotte Luff
- Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Patrycja Dzialecka
- Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Boris Botzanowski
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Florian Missey
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Ibrahima Ngom
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Stanislas Lagarde
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
- Department of Epileptology, APHM, Timone Hospital, Marseille, France
| | - Fabrice Bartolomei
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
- Department of Epileptology, APHM, Timone Hospital, Marseille, France
| | - Antonino Cassara
- Foundation for Research on Information Technologies in Society, Zurich, Switzerland
| | - Esra Neufeld
- Foundation for Research on Information Technologies in Society, Zurich, Switzerland
| | - Viktor Jirsa
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Romain Carron
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
- Department of Functional and Stereotactic Neurosurgery, Timone University Hospital, Marseille, France
| | - Nir Grossman
- Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Adam Williamson
- Aix Marseille University:, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
- Department of Medicine, Center for Bioelectronic Medicine, Karolinska Institute, Stockholm, Sweden
- *Correspondence: Adam Williamson, ;
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Tang M, Yamamoto T. Progress in Understanding Radiofrequency Heating and Burn Injuries for Safer MR Imaging. Magn Reson Med Sci 2022; 22:7-25. [PMID: 35228437 PMCID: PMC9849420 DOI: 10.2463/mrms.rev.2021-0047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
RF electromagnetic wave exposure during MRI scans induces heat and occasionally causes burn injuries to patients. Among all the types of physical injuries that have occurred during MRI examinations, RF burn injuries are the most common ones. The number of RF burn injuries increases as the static magnetic field of MRI systems increases because higher RFs lead to higher heating. The commonly believed mechanisms of RF burn injuries are the formation of a conductive loop by the patient's posture or cables, such as an electrocardiogram lead; however, the mechanisms of RF burn injuries that occur at the contact points, such as the bore wall and the elbow, remain unclear. A comprehensive understanding of RF heating is needed to address effective countermeasures against all RF burn injuries for safe MRI examinations. In this review, we summarize the occurrence of RF burn injury cases by categorizing RF burn injuries reported worldwide in recent decades. Safety standards and regulations governing RF heating that occurs during MRI examinations are presented, along with their theoretical and physiological backgrounds. The experimental assessment techniques for RF heating are then reviewed, and the development of numerical simulation techniques is explained. In addition, a comprehensive theoretical interpretation of RF burn injuries is presented. By including the results of recent experimental and numerical simulation studies on RF heating, this review describes the progress achieved in understanding RF heating from the standpoint of MRI burn injury prevention.
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Affiliation(s)
- Minghui Tang
- Department of Diagnostic Imaging, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Toru Yamamoto
- Division of Biomedical Engineering and Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan,Corresponding author: Faculty of Health Sciences, Hokkaido University, Kita 12 Nishi 5, Kita-ku, Sapporo, Hokkaido 060-0812, Japan. Phone: +81-11-706-3412, Fax: +81-11-706-4916, E-mail:
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Yao A, Goren T, Samaras T, Kuster N, Kainz W. Radiofrequency-induced heating of broken and abandoned implant leads during magnetic resonance examinations. Magn Reson Med 2021; 86:2156-2164. [PMID: 34080721 PMCID: PMC8362172 DOI: 10.1002/mrm.28836] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 04/15/2021] [Accepted: 04/21/2021] [Indexed: 12/21/2022]
Abstract
Purpose The risks of RF‐induced heating of active implantable medical device (AIMD) leads during MR examinations must be well understood and realistically assessed. In this study, we evaluate the potential additional risks of broken and abandoned (cut) leads. Methods First, we defined a generic AIMD with a metallic implantable pulse generator (IPG) and a 100‐cm long lead containing 1 or 2 wires. Next, we numerically estimated the deposited in vitro lead‐tip power for an intact lead, as well as with wire breaks placed at 10 cm intervals. We studied the effect of the break size (wire gap width), as well as the presence of an intact wire parallel to the broken wire, and experimentally validated the numeric results for the configurations with maximum deposited in vitro lead‐tip power. Finally, we performed a Tier 3 assessment of the deposited in vivo lead‐tip power for the intact and broken lead in 4 high resolution virtual population anatomic models for over 54,000 MR examination scenarios. Results The enhancement of the deposited lead‐tip power for the broken leads, compared to the intact lead, reached 30‐fold in isoelectric exposure, and 16‐fold in realistic clinical exposures. The presence of a nearby intact wire, or even a nearby broken wire, reduced this enhancement factor to <7‐fold over the intact lead. Conclusion Broken and abandoned leads can pose increased risk of RF‐induced lead‐tip heating to patients undergoing MR examinations. The potential enhancement of deposited in vivo lead‐tip power depends on location and type of the wire break, lead design, and clinical routing of the lead, and should be carefully considered when performing risk assessment for MR examinations and MR conditional labeling.
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Affiliation(s)
- Aiping Yao
- Foundation of Research on Information Technologies in Society (IT'IS), Zurich, Switzerland
| | - Tolga Goren
- Foundation of Research on Information Technologies in Society (IT'IS), Zurich, Switzerland
| | - Theodoros Samaras
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Niels Kuster
- Foundation of Research on Information Technologies in Society (IT'IS), Zurich, Switzerland.,Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Wolfgang Kainz
- Center for Devices and Radiological Health, Food and Drug Administration (FDA), Silver Spring, Maryland, USA
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Yao A, Zastrow E, Neufeld E, Kuster N. Efficient and Reliable Assessment of the Maximum Local Tissue Temperature Increase at the Electrodes of Medical Implants under MRI Exposure. Bioelectromagnetics 2019; 40:422-433. [DOI: 10.1002/bem.22208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 06/27/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Aiping Yao
- Foundation for Research on Information Technologies in Society (IT'IS) Zurich Switzerland
- Swiss Federal Institute of Technology (ETH) Zurich Zurich Switzerland
| | - Earl Zastrow
- Foundation for Research on Information Technologies in Society (IT'IS) Zurich Switzerland
| | - Esra Neufeld
- Foundation for Research on Information Technologies in Society (IT'IS) Zurich Switzerland
| | - Niels Kuster
- Foundation for Research on Information Technologies in Society (IT'IS) Zurich Switzerland
- Swiss Federal Institute of Technology (ETH) Zurich Zurich Switzerland
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