1
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Eijbersen MA, Steensma BR, van den Berg CAT, Raaijmakers AJE. An improved method to measure transfer functions using MRI. Magn Reson Med 2024; 92:2246-2260. [PMID: 38860561 DOI: 10.1002/mrm.30179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 05/07/2024] [Accepted: 05/12/2024] [Indexed: 06/12/2024]
Abstract
PURPOSE A previously published method for MRI-based transfer function assessment makes use of the so-called transceive phase assumption (TPA). This limits its applicability to shorter leads and/or lower field strengths. A new method is presented where the background electric field is determined from bothB 1 + $$ {\mathrm{B}}_1^{+} $$ - andB 1 - $$ {\mathrm{B}}_1^{-} $$ -field distributions, avoiding the TPA and making it more generally applicable. THEORY AND METHODS TheseB 1 $$ {\mathrm{B}}_1 $$ -distributions are determined from a spoiled gradient echo multiflip angle acquisition. From the separatedB 1 $$ {\mathrm{B}}_1 $$ -components the background electrical field and the induced current are computed. Further improvement is achieved by recasting theB 1 $$ {\mathrm{B}}_1 $$ -field model as a "magnitude squared least squares" problem. The proposed reconstruction method is used to determine transfer functions of various copper wire lengths up to 40 cm inside an elliptical ASTM phantom. The method is first tested on EM-simulated data and subsequently phantom and bench measurements are used to determine transfer functions experimentally. RESULTS In silica reconstructions demonstrate the validity of the proposedB 1 $$ {\mathrm{B}}_1 $$ -field model resulting in highly accurate reconstructedB 1 $$ {\mathrm{B}}_1 $$ -fields, currents, incident electric fields and transfer functions. The experimental results show slight deviations in the field model, however, resulting transfer functions are accurately determined with high similarity to simulations and comparable to bench measurements. CONCLUSION A more generally applicable method for MRI-based transfer function assessment is presented. The proposed method circumvents phase assumptions making it applicable for longer objects and/or higher field strengths. Additional improvements are implemented in theB 1 $$ {\mathrm{B}}_1 $$ -mapping method and the solution algorithm.
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Affiliation(s)
- Michael A Eijbersen
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
- Computational Imaging Group for MR Therapy and Diagnostics, Center for Image Sciences, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bart R Steensma
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
- Computational Imaging Group for MR Therapy and Diagnostics, Center for Image Sciences, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Cornelis A T van den Berg
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
- Computational Imaging Group for MR Therapy and Diagnostics, Center for Image Sciences, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Alexander J E Raaijmakers
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
- Computational Imaging Group for MR Therapy and Diagnostics, Center for Image Sciences, University Medical Center Utrecht, Utrecht, The Netherlands
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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2
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Jiang F, Henry KR, Bhusal B, Sanpitak P, Webster G, Popescu A, Laternser C, Kim D, Golestanirad L. Age Matters: A Comparative Study of RF Heating of Epicardial and Endocardial Electronic Devices in Pediatric and Adult Phantoms during Cardiothoracic MRI. Diagnostics (Basel) 2023; 13:2847. [PMID: 37685385 PMCID: PMC10486594 DOI: 10.3390/diagnostics13172847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 06/29/2023] [Accepted: 08/04/2023] [Indexed: 09/10/2023] Open
Abstract
This study focused on the potential risks of radiofrequency-induced heating of cardiac implantable electronic devices (CIEDs) in children and adults with epicardial and endocardial leads of varying lengths during cardiothoracic MRI scans. Infants and young children are the primary recipients of epicardial CIEDs, though the devices have not been approved as MR conditional by the FDA due to limited data, leading to pediatric hospitals either refusing the MRI service to most pediatric CIED patients or adopting a scan-all strategy based on results from adult studies. The study argues that risk-benefit decisions should be made on an individual basis. We used 120 clinically relevant epicardial and endocardial device configurations in adult and pediatric anthropomorphic phantoms to determine the temperature rise during RF exposure at 1.5 T. The results showed that there was significantly higher RF heating of epicardial leads than endocardial leads in the pediatric phantom, but not in the adult phantom. Additionally, body size and lead length significantly affected RF heating, with RF heating up to 12 °C observed in models based on younger children with short epicardial leads. The study provides evidence-based knowledge on RF-induced heating of CIEDs and highlights the importance of making individual risk-benefit decisions when assessing the potential risks of MRI scans in pediatric CIED patients.
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Affiliation(s)
- Fuchang Jiang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Kaylee R. Henry
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Bhumi Bhusal
- Department of Radiology, Northwestern University, Chicago, IL 60611, USA
| | - Pia Sanpitak
- Department of Radiology, Northwestern University, Chicago, IL 60611, USA
| | - Gregory Webster
- Division of Cardiology, Ann and Robert H. Lurie Children’s Hospital of Chicago, Northwestern University, Chicago, IL 60611, USA
| | - Andrada Popescu
- Division of Medical Imaging, Ann and Robert H. Lurie Children’s Hospital of Chicago, Northwestern University, Chicago, IL 60611, USA
| | - Christina Laternser
- Division of Cardiology, Ann and Robert H. Lurie Children’s Hospital of Chicago, Northwestern University, Chicago, IL 60611, USA
| | - Daniel Kim
- Department of Radiology, Northwestern University, Chicago, IL 60611, USA
| | - Laleh Golestanirad
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Radiology, Northwestern University, Chicago, IL 60611, USA
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3
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Vu J, Bhusal B, Nguyen BT, Sanpitak P, Nowac E, Pilitsis J, Rosenow J, Golestanirad L. A comparative study of RF heating of deep brain stimulation devices in vertical vs. horizontal MRI systems. PLoS One 2022; 17:e0278187. [PMID: 36490249 PMCID: PMC9733854 DOI: 10.1371/journal.pone.0278187] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 11/11/2022] [Indexed: 12/13/2022] Open
Abstract
The majority of studies that assess magnetic resonance imaging (MRI) induced radiofrequency (RF) heating of the tissue when active electronic implants are present have been performed in horizontal, closed-bore MRI systems. Vertical, open-bore MRI systems have a 90° rotated magnet and a fundamentally different RF coil geometry, thus generating a substantially different RF field distribution inside the body. Little is known about the RF heating of elongated implants such as deep brain stimulation (DBS) devices in this class of scanners. Here, we conducted the first large-scale experimental study investigating whether RF heating was significantly different in a 1.2 T vertical field MRI scanner (Oasis, Fujifilm Healthcare) compared to a 1.5 T horizontal field MRI scanner (Aera, Siemens Healthineers). A commercial DBS device mimicking 30 realistic patient-derived lead trajectories extracted from postoperative computed tomography images of patients who underwent DBS surgery at our institution was implanted in a multi-material, anthropomorphic phantom. RF heating around the DBS lead was measured during four minutes of high-SAR RF exposure. Additionally, we performed electromagnetic simulations with leads of various internal structures to examine this effect on RF heating. When controlling for RMS B1+, the temperature increase around the DBS lead-tip was significantly lower in the vertical scanner compared to the horizontal scanner (0.33 ± 0.24°C vs. 4.19 ± 2.29°C). Electromagnetic simulations demonstrated up to a 17-fold reduction in the maximum of 0.1g-averaged SAR in the tissue surrounding the lead-tip in the vertical scanner compared to the horizontal scanner. Results were consistent across leads with straight and helical internal wires. Radiofrequency heating and power deposition around the DBS lead-tip were substantially lower in the 1.2 T vertical scanner compared to the 1.5 T horizontal scanner. Simulations with different lead structures suggest that the results may extend to leads from other manufacturers.
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Affiliation(s)
- Jasmine Vu
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Bhumi Bhusal
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Bach T. Nguyen
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Pia Sanpitak
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Elizabeth Nowac
- Illinois Bone and Joint Institute (IBJI), Wilmette, Illinois, United States of America
| | - Julie Pilitsis
- Department of Neurosciences & Experimental Therapeutics, Albany Medical College, Albany, New York, United States of America
| | - Joshua Rosenow
- Department of Neurosurgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Laleh Golestanirad
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- * E-mail:
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Fujita Y, Khoo HM, Hirayama M, Kawahara M, Koyama Y, Tarewaki H, Arisawa A, Yanagisawa T, Tani N, Oshino S, Lemieux L, Kishima H. Evaluating the Safety of Simultaneous Intracranial Electroencephalography and Functional Magnetic Resonance Imaging Acquisition Using a 3 Tesla Magnetic Resonance Imaging Scanner. Front Neurosci 2022; 16:921922. [PMID: 35812224 PMCID: PMC9259878 DOI: 10.3389/fnins.2022.921922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 05/25/2022] [Indexed: 11/13/2022] Open
Abstract
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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Affiliation(s)
- Yuya Fujita
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan
| | - Hui Ming Khoo
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan
- *Correspondence: Hui Ming Khoo,
| | - Miki Hirayama
- Department of Radiology, Osaka University Hospital, Suita, Japan
| | - Masaaki Kawahara
- Department of Radiology, Osaka University Hospital, Suita, Japan
| | - Yoshihiro Koyama
- Department of Radiology, Osaka University Hospital, Suita, Japan
| | | | - Atsuko Arisawa
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Takufumi Yanagisawa
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan
| | - Naoki Tani
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan
| | - Satoru Oshino
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan
| | - Louis Lemieux
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Haruhiko Kishima
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan
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5
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A perturbation approach for ultrafast calculation of RF field enhancements near medical implants in MRI. Sci Rep 2022; 12:4224. [PMID: 35273313 PMCID: PMC8913743 DOI: 10.1038/s41598-022-08004-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 02/22/2022] [Indexed: 11/08/2022] Open
Abstract
Patients with medical implants often are deprived of magnetic resonance imaging examination because of safety risks. One specific risk is the enhancement of the radiofrequency fields around the medical implant potentially resulting in significant tissue heating and damage. The assessment of this enhancement is a computationally demanding task, with simulations taking hours or days to converge. Conventionally the source of the radiofrequency fields, patient anatomy, and the medical implant are simulated concurrently. To alleviate the computational burden, we reformulate a fast simulation method that views the medical implant as a small perturbation of the simulation domain without the medical implant and calculates the radiofrequency fields associated with this perturbation. Previously, this method required an extensive offline stage where the result is intractable for large simulation domains. Currently, this offline stage is no longer required and the method is completely online. The proposed method results in comparable radiofrequency fields but is orders of magnitude faster compared to standard simulation technique; the finite-difference time-domain, the finite-sums, and the finite element methods. This acceleration could enable patient-specific and potentially online radiofrequency safety assessment.
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6
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Bhusal B, Bhattacharyya P, Baig T, Jones S, Martens M. Effect of inter-electrode RF coupling on heating patterns of wire-like conducting implants in MRI. Magn Reson Med 2022; 87:2933-2946. [PMID: 35092097 DOI: 10.1002/mrm.29177] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 12/16/2021] [Accepted: 01/09/2022] [Indexed: 11/05/2022]
Abstract
PURPOSE In this study, the effects of RF coupling on the magnitude and spatial patterns of RF-induced heating near multiple wire-like conducting implants (such as simultaneous electrical stimulation of stereoelectroencephalography electrodes) during MRI were assessed. METHODS Simulations and experimental measurements of RF-induced temperature increases near partially immersed wire-like conductors were performed using a phantom with a transmit/receive head coil on a 3T MRI system. The conductors consisted of either a pair of wires or a single simultaneous electrical stimulation of stereoelectroencephalography electrode with multiple contacts, and the locations and lengths of the conductors were varied to study the effect of electromagnetic coupling on RF-induced heating. RESULTS The temperature increase near a wire within the phantom was dependent not only on its own location and length, but also on the locations and lengths of the other partially immersed wires. In the configurations that were studied, the presence of a second implant could increase the heating near the tip of the conductor by as much as 95%. CONCLUSION The level of RF-induced heating during an MR scan is affected significantly by RF coupling when more than one wire-like implant is present. In some of the configurations studied, the heating was increased by the presence of a second conductor partially immersed in the phantom. Thus, RF coupling is an important factor to consider in the assessment of safety issues for MRI when multiple implants are present.
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Affiliation(s)
- Bhumi Bhusal
- Department of Radiology, Northwestern University, Chicago, Illinois, USA
| | | | - Tanvir Baig
- Department of Radiation Oncology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Stephen Jones
- Imaging Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Michael Martens
- Department of Physics, Case Western Reserve University, Cleveland, Ohio, USA
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7
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Nguyen BT, Bhusal B, Rahsepar AA, Fawcett K, Lin S, Marks DS, Passman R, Nieto D, Niemzcura R, Golestanirad L. Safety of MRI in patients with retained cardiac leads. Magn Reson Med 2021; 87:2464-2480. [PMID: 34958685 PMCID: PMC8919805 DOI: 10.1002/mrm.29116] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 11/18/2021] [Accepted: 11/20/2021] [Indexed: 11/17/2022]
Abstract
Purpose To evaluate the safety of MRI in patients with fragmented retained leads (FRLs) through numerical simulation and phantom experiments. Methods Electromagnetic and thermal simulations were performed to determine the worst‐case RF heating of 10 patient‐derived FRL models during MRI at 1.5 T and 3 T and at imaging landmarks corresponding to head, chest, and abdomen. RF heating measurements were performed in phantoms implanted with reconstructed FRL models that produced highest heating in numerical simulations. The potential for unintended tissue stimulation was assessed through a conservative estimation of the electric field induced in the tissue due to gradient‐induced voltages developed along the length of FRLs. Results In simulations under conservative approach, RF exposure at B1+ ≤ 2 µT generated cumulative equivalent minutes (CEM)43 < 40 at all imaging landmarks at both 1.5 T and 3 T, indicating no thermal damage for acquisition times (TAs) < 10 min. In experiments, the maximum temperature rise when FRLs were positioned at the location of maximum electric field exposure was measured to be 2.4°C at 3 T and 2.1°C at 1.5 T. Electric fields induced in the tissue due to gradient‐induced voltages remained below the threshold for cardiac tissue stimulation in all cases. Conclusions Simulation and experimental results indicate that patients with FRLs can be scanned safely at both 1.5 T and 3 T with most clinical pulse sequences.
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Affiliation(s)
- Bach T Nguyen
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Bhumi Bhusal
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Amir Ali Rahsepar
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Kate Fawcett
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Stella Lin
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Daniel S Marks
- Department of Electrophysiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Rod Passman
- Department of Electrophysiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Donny Nieto
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Richard Niemzcura
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Laleh Golestanirad
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, USA
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8
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Stijnman PRS, Erturk MA, van den Berg CAT, Raaijmakers AJE. A single setup approach for the MRI-based measurement and validation of the transfer function of elongated medical implants. Magn Reson Med 2021; 86:2751-2765. [PMID: 34036617 PMCID: PMC8596675 DOI: 10.1002/mrm.28840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 04/23/2021] [Accepted: 04/23/2021] [Indexed: 12/15/2022]
Abstract
PURPOSE To propose a single setup using the MRI to both measure and validate the transfer function (TF) of linear implants. Conventionally, the TF of an implant is measured in one bench setup and validated using another. METHODS It has been shown that the TF can be measured using MRI. To validate this measurement, the implant is exposed to different incident electric fields, while the temperature increase at the tip is monitored. For a good validation, the incident electric fields that the implant is exposed to should be orthogonal. We perform a simulation study on six different methods that change the incident electric field. Afterward, a TF measurement and validation study using the best method from the simulations is performed. This is done with fiberoptic temperature probes at 1.5 T for four linear implant structures using the proposed single setup. RESULTS The simulation study showed that positioning local transmit coils at different locations along the lead trajectory has a similar validation quality compared with changing the implant trajectory (ie, the conventional validation method). For the validation study that was performed, an R2 ≥ 0.91 was found for the four investigated leads. CONCLUSION A single setup to both measure and validate the transfer function using local transmit coils has been shown to work. The benefits of using the proposed validation method are that there is only one setup required instead of two and the implant trajectory is not varied; therefore, the relative distance between the leap tip and the temperature probe is constant.
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Affiliation(s)
- Peter R. S. Stijnman
- Computational Imaging Group for MRI diagnostics and therapyCenter for Image Sciences UMC UtrechtUtrechtthe Netherlands
- Department of Biomedical EngineeringEindhoven University of TechnologyEindhoven, Brabantthe Netherlands
| | - M. Arcan Erturk
- Restorative Therapies Group, Implantables R&D, Medtronic PLCMinneapolisMinnesotaUSA
| | - Cornelis A. T. van den Berg
- Computational Imaging Group for MRI diagnostics and therapyCenter for Image Sciences UMC UtrechtUtrechtthe Netherlands
| | - Alexander J. E. Raaijmakers
- Computational Imaging Group for MRI diagnostics and therapyCenter for Image Sciences UMC UtrechtUtrechtthe Netherlands
- Department of Biomedical EngineeringEindhoven University of TechnologyEindhoven, Brabantthe Netherlands
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Bhusal B, Stockmann J, Guerin B, Mareyam A, Kirsch J, Wald LL, Nolt MJ, Rosenow J, Lopez-Rosado R, Elahi B, Golestanirad L. Safety and image quality at 7T MRI for deep brain stimulation systems: Ex vivo study with lead-only and full-systems. PLoS One 2021; 16:e0257077. [PMID: 34492090 PMCID: PMC8423254 DOI: 10.1371/journal.pone.0257077] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 08/23/2021] [Indexed: 11/19/2022] Open
Abstract
Ultra-high field MRI at 7 T can produce much better visualization of sub-cortical structures compared to lower field, which can greatly help target verification as well as overall treatment monitoring for patients with deep brain stimulation (DBS) implants. However, use of 7 T MRI for such patients is currently contra-indicated by guidelines from the device manufacturers due to the safety issues. The aim of this study was to provide an assessment of safety and image quality of ultra-high field magnetic resonance imaging at 7 T in patients with deep brain stimulation implants. We performed experiments with both lead-only and complete DBS systems implanted in anthropomorphic phantoms. RF heating was measured for 43 unique patient-derived device configurations. Magnetic force measurements were performed according to ASTM F2052 test method, and device integrity was assessed before and after experiments. Finally, we assessed electrode artifact in a cadaveric brain implanted with an isolated DBS lead. RF heating remained below 2°C, similar to a fever, with the 95% confidence interval between 0.38°C-0.52°C. Magnetic forces were well below forces imposed by gravity, and thus not a source of concern. No device malfunctioning was observed due to interference from MRI fields. Electrode artifact was most noticeable on MPRAGE and T2*GRE sequences, while it was minimized on T2-TSE images. Our work provides the safety assessment of ultra-high field MRI at 7 T in patients with DBS implants. Our results suggest that 7 T MRI may be performed safely in patients with DBS implants for specific implant models and MRI hardware.
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Affiliation(s)
- Bhumi Bhusal
- Department of Radiology, Northwestern University, Chicago, IL, United States of America
| | - Jason Stockmann
- Department of Radiology, Harvard Medical School, Boston, MA, United States of America
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States of America
| | - Bastien Guerin
- Department of Radiology, Harvard Medical School, Boston, MA, United States of America
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States of America
| | - Azma Mareyam
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States of America
| | - John Kirsch
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States of America
| | - Lawrence L. Wald
- Department of Radiology, Harvard Medical School, Boston, MA, United States of America
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States of America
| | - Mark J. Nolt
- Department of Neurosurgery, Northwestern University, Chicago, IL, United States of America
| | - Joshua Rosenow
- Department of Neurosurgery, Northwestern University, Chicago, IL, United States of America
| | - Roberto Lopez-Rosado
- Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, United States of America
| | - Behzad Elahi
- Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, United States of America
| | - Laleh Golestanirad
- Department of Radiology, Northwestern University, Chicago, IL, United States of America
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
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10
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Nguyen BT, Pilitsis J, Golestanirad L. The effect of simulation strategies on prediction of power deposition in the tissue around electronic implants during magnetic resonance imaging. ACTA ACUST UNITED AC 2020; 65:185007. [DOI: 10.1088/1361-6560/abac9f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Bhusal B, Nguyen BT, Sanpitak PP, Vu J, Elahi B, Rosenow J, Nolt MJ, Lopez‐Rosado R, Pilitsis J, DiMarzio M, Golestanirad L. Effect of Device Configuration and Patient's Body Composition on the
RF
Heating and Nonsusceptibility Artifact of Deep Brain Stimulation Implants During
MRI
at 1.5T and 3T. J Magn Reson Imaging 2020; 53:599-610. [DOI: 10.1002/jmri.27346] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- Bhumi Bhusal
- Department of Radiology Northwestern University Chicago Illinois USA
| | - Bach T. Nguyen
- Department of Radiology Northwestern University Chicago Illinois USA
| | - Pia P. Sanpitak
- Department of Biomedical Engineering Northwestern University Chicago Illinois USA
| | - Jasmine Vu
- Department of Radiology Northwestern University Chicago Illinois USA
- Department of Biomedical Engineering Northwestern University Chicago Illinois USA
| | - Behzad Elahi
- Department of Physical Therapy and Human Movement Sciences Northwestern University Chicago Illinois USA
| | - Joshua Rosenow
- Department of Neurosurgery Northwestern University Chicago Illinois USA
| | - Mark J. Nolt
- Department of Neurosurgery Northwestern University Chicago Illinois USA
| | - Roberto Lopez‐Rosado
- Department of Physical Therapy and Human Movement Sciences Northwestern University Chicago Illinois USA
| | - Julie Pilitsis
- Department of Neurosciences and Experimental Therapeutics Albany Medical College Albany New York USA
| | - Marisa DiMarzio
- Department of Neurosciences and Experimental Therapeutics Albany Medical College Albany New York USA
| | - Laleh Golestanirad
- Department of Radiology Northwestern University Chicago Illinois USA
- Department of Biomedical Engineering Northwestern University Chicago Illinois USA
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Bhusal B, Nguyen BT, Vu J, Elahi B, Rosenow J, Nolt MJ, Pilitsis J, DiMarzio M, Golestanirad L. Device Configuration and Patient's Body Composition Significantly Affect RF Heating of Deep Brain Stimulation Implants During MRI: An Experimental Study at 1.5T and 3T. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:5192-5197. [PMID: 33019155 PMCID: PMC10900233 DOI: 10.1109/embc44109.2020.9175833] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Patients with deep brain stimulation (DBS) devices have limited access to magnetic resonance imaging (MRI) due to safety concerns associated with RF heating generated around the implant. The problem of predicting RF heating of conductive leads is complex with a large parameter space and several interplaying factors. Recently however, off-label use of MRI in patients with DBS devices has been reported based on limited safety assessments, raising the concern that potentially dangerous scenarios may have been overlooked. In this work, we present results of a systematic assessment of RF heating of a commercial DBS device during MRI at 1.5T and 3T, taking into account the effect of device configuration, imaging landmark, and patient's body composition. Ninety-six (96) RF heating measurements were performed using anthropomorphic phantoms implanted with a full DBS system. We evaluated eight clinically relevant device configurations, implanted in phantoms with different material compositions, and imaged at three different landmarks (head, shoulder, and lower chest) in 1.5 T and 3T scanners. We observed a substantial fluctuation in the RF heating depending on phantom's composition and device configuration. RF heating in the brain-mimicking gel varied from 0.1°C to 12°C during 1.5 T MRI and from <0.1°C to 4.5°C during 3T MRI. We also observed that certain device configurations consistently reduced RF heating across different phantom compositions, imaging landmarks, and MRI transmit frequencies.
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Modeling radiofrequency responses of realistic multi-electrode leads containing helical and straight wires. MAGMA (NEW YORK, N.Y.) 2020; 33:421-437. [PMID: 31745756 PMCID: PMC7230065 DOI: 10.1007/s10334-019-00793-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 09/27/2019] [Accepted: 10/24/2019] [Indexed: 11/04/2022]
Abstract
Purpose To present a modeling workflow for the evaluation of a lead electromagnetic model (LEM) consisting of a transfer function (TF) and a calibration factor. The LEM represents an analytical relationship between the RF response of a lead and the incident electromagnetic field. The study also highlights the importance of including key geometric details of the lead and the electrode when modeling multi-electrode leads. Methods The electrical and thermal responses of multi-electrode leads with helical and straight wires were investigated using 3D electromagnetic (EM) and thermal co-simulations. The net dissipated power (P) around each lead electrode and the net temperature increase at the electrodes (ΔT) were obtained for a set of incident EM fields with different spatial distributions. A reciprocity approach was used to determine a TF for each electrode based on the results of the computational model. The evaluation of the calibration factors and the TF validation were performed using the linear regression of P versus the LEM predictions. Results P and ΔT were investigated for four multi-electrode leads and four single-electrode leads containing either helical or straight wires. All electrodes of the multi-electrode lead were found to be points of high power deposition and temperature rise. The LEMs for the individual electrodes varied substantially. A significant dependence of the calibration factors on the surrounding tissue medium was also found. Finally, the model showed that the TF, the calibration factor, P and ΔT for multi-electrode leads differ significantly from those for single-electrode leads. Conclusion These results highlight the need to evaluate a LEM for each electrode of a multi-electrode lead as well as for each possible surrounding medium. It is also shown that the results derived from simulations based on simplified single-electrode leads can significantly mislead multi-electrode lead analyses.
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Needle Heating During Interventional Magnetic Resonance Imaging at 1.5- and 3.0-T Field Strengths. Invest Radiol 2020; 55:396-404. [DOI: 10.1097/rli.0000000000000649] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Özen AC, Silemek B, Lottner T, Atalar E, Bock M. MR safety watchdog for active catheters: Wireless impedance control with real-time feedback. Magn Reson Med 2020; 84:1048-1060. [PMID: 31961965 DOI: 10.1002/mrm.28153] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/29/2019] [Accepted: 12/09/2019] [Indexed: 12/13/2022]
Abstract
PURPOSE To dynamically minimize radiofrequency (RF)-induced heating of an active catheter through an automatic change of the termination impedance. METHODS A prototype wireless module was designed that modifies the input impedance of an active catheter to keep the temperature rise during MRI below a threshold, ΔTmax . The wireless module (MR safety watchdog; MRsWD) measures the local temperature at the catheter tip using either a built-in thermistor or external data from a fiber-optical thermometer. It automatically changes the catheter input impedance until the temperature rise during MRI is minimized. If ΔTmax is exceeded, RF transmission is blocked by a feedback system. RESULTS The thermistor and fiber-optical thermometer provided consistent temperature data in a phantom experiment. During MRI, the MRsWD was able to reduce the maximum temperature rise by 25% when operated in real-time feedback mode. CONCLUSION This study demonstrates the technical feasibility of an MRsWD as an alternative or complementary approach to reduce RF-induced heating of active interventional devices. The automatic MRsWD can reduce heating using direct temperature measurements at the tip of the catheter. Given that temperature measurements are intrinsically slow, for a clinical implementation, a faster feedback parameter would be required such as the RF currents along the catheter or scattered electric fields at the tip.
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Affiliation(s)
- Ali Caglar Özen
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Consortium for Translational Cancer Research Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Berk Silemek
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey.,Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany
| | - Thomas Lottner
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Freiburg, Germany
| | - Ergin Atalar
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey.,Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
| | - Michael Bock
- Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Freiburg, Germany
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Wang Y, Wang Q, Liu J, Zeng Q, Zheng J, Kainz W, Chen J. On the development of equivalent medium for active implantable device radiofrequency safety assessment. Magn Reson Med 2019; 82:1164-1176. [DOI: 10.1002/mrm.27785] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 03/06/2019] [Accepted: 04/04/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Yu Wang
- Department of Electrical and Computer Engineering University of Houston Houston Texas 77204‐4005
| | - Qingyan Wang
- Department of Electrical and Computer Engineering University of Houston Houston Texas 77204‐4005
| | - Jingshen Liu
- Department of Electrical and Computer Engineering University of Houston Houston Texas 77204‐4005
| | - Qi Zeng
- Department of Electrical and Computer Engineering University of Houston Houston Texas 77204‐4005
| | - Jianfeng Zheng
- Department of Electrical and Computer Engineering University of Houston Houston Texas 77204‐4005
| | - Wolfgang Kainz
- Division of Biomedical Physics U.S. FDA Silver Spring Maryland 20993
| | - Ji Chen
- Department of Electrical and Computer Engineering University of Houston Houston Texas 77204‐4005
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Risk assessment of copper-containing contraceptives: the impact for women with implanted intrauterine devices during clinical MRI and CT examinations. Eur Radiol 2018; 29:2812-2820. [PMID: 30456586 DOI: 10.1007/s00330-018-5864-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/28/2018] [Accepted: 10/25/2018] [Indexed: 12/19/2022]
Abstract
OBJECTIVES To assess the risks for implant users with copper-containing intrauterine devices (IUDs) during MR and CT examinations. METHODS A tissue-mimicking phantom suitable for all experiments within this study was developed. Seven different types of copper IUDs were evaluated. Heating and dislocation of each IUD were investigated at two clinically relevant positions in 1.5 T and 3 T MR scanners. Artifacts in the field of view caused by each tested IUD were determined for clinical MR and CT imaging. RESULTS No significant heating of any tested IUD was detected during MR measurements. The temperature increase was less than 0.6 K for all IUDs. Neither angular deflection nor translation of any IUD was detected. Artifacts in MR images were limited to the very vicinity of the IUDs except for one IUD containing a steel-visualizing element. Streaking artifacts in CT were severe (up to 75.5%) in the slices including the IUD. CONCLUSION No significant risk possibly harming the patient was determined during this phantom study, deeming MR examinations safe for women with an implanted copper IUD. Image quality was more impaired for CT than for MR imaging and needs careful consideration during diagnosis. KEY POINTS • Risk assessment of copper-containing IUDs with regard to heating, dislocation, and artifacts during MR and CT imaging. • Neither significant heating nor dislocation was determined in MR; image quality was more impaired for CT than for MR imaging and needs careful consideration during diagnosis. • The tested IUDs pose no additional risks for implant users during MR and CT examinations.
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