Abstract
Objective
To propose and validate a variation of the classic techniques for the estimation of the transfer function (TF) of a real pacemaker (PM) lead.
Methods
The TF of three commercially available PM leads was measured by combining data from experimental measurements and numerical simulations generated by three sources: a) the experimental local SAR at the tip of the PM lead (single measurement point) exposed to a 64 MHz birdcage body coil; b) the experimental current distribution along the PM lead, obtained by directly injecting a 64 MHz signal inside the lead; c) the electric field (E-field) simulated with a computational model of the 64 MHz birdcage body coil adopted in the experimental measurement performed in a). The effect of the lead trajectory on the estimation of the TF was also estimated.
Results
The proposed methodology was validated by comparing the SAR obtained from the PM lead TF with experimental measurements: a maximum difference of 2.2 dB was observed. It was also shown that the estimation of the TF cannot be considered independent with the lead trajectory: a variation of the SAR estimation up to 3.4 dB was observed.
Conclusion
For the three PM lead tested, the error in the SAR estimation is within the uncertainty level of SAR measurements (± 2 dB). Additionally, the estimation of the TF using the reciprocity principle is influenced by the particular lead trajectory adopted, even if the consequent variability in the SAR estimation is still close to the uncertainty level of SAR measurements.
Similar content being viewed by others
References
Sutton R, Kanal E, Wilkoff BL, Bello D, Luechinger R, Jenniskens I, Hull M, Sommer T (2008) Safety of magnetic resonance imaging of patients with a new Medtronic EnRhythm MRI SureScan pacing system: clinical study design. Trials 2(9):68
Ferreira AM, Costa F, Tralhão A, Marques H, Cardim N, Adragão P (2014) MRI-conditional pacemakers: current perspectives. Med Devices (Auckl) 7:115–124
FDA PMA approval database: https://www.fda.gov/medical-devices/device-approvals-denials-and-clearances/pma-approvals. Last visited 31/07/2020.
ISO/TS 10974:2018. Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device.
Park SM, Kamondetdacha R, Nyenhuis JA (2007) Calculation of MRI-induced heating of an implanted medical lead wire with an electric field transfer function. J Magn Reson Imaging 26(5):1278–1285
Zastrow E, Capstick M, Cabot E, Kuster N (2014) Piece-wise excitation system for the characterization of local RF-induced heating of AIMD during MR exposure. International Symposium on Electromagnetic Compatibility, Tokyo
Feng S, Qiang R, Kainz W, Chen J (2015) A technique to evaluate mri-induced electric fields at the ends of practical implanted lead. IEEE Trans Microw Theory Tech 63:1
Missoffe A, Aissani S (2018) Experimental setup for transfer function measurement to assess RF heating of medical leads in MRI: Validation in the case of a single wire. Magn Reson Med 79(3):1766–1772
Tokaya JP, Raaijmakers AJE, Luijten PR, Bakker JF, van den Berg CAT (2017) MRI-based transfer function determination for the assessment of implant safety. Magn Reson Med 78(6):2449–2459
Tokaya JP, Raaijmakers AJE, Luijten PR, van den Berg CAT (2018) MRI-based, wireless determination of the transfer function of a linear implant: Introduction of the transfer matrix. Magn Reson Med 80(6):2771–2784
Kozlov M, Kainz W, Daniel L (2020) Influence of metallic shielding on radio frequency energy-induced heating of leads with straight and helical wires: a numerical case study. IEEE Trans Microwave Theory Tech 68(2):1–7
Min X and Sison S. (2018) Transfer functions of a spinal cord stimulation system in mixed media and homogeneous media for estimation of rf heating during MRI scans. 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), pp 18–21.
Kurpad KKN, Liu J, Stadnik PJ, Von Arx J, Stotts L, Kainz W, and Chen J. MRI RF Safety of Active Implantable Medical Devices (AIMDs): Effect of Conductivity of Tissue Simulating Media on Device Model Accuracy. Proc. 26th Annu. Meeting Int. Soc. of Magn. Reson. Med. 2018 June 16-21, Paris, France, pp. 4075.
Min X, Sison S (2017) Impact of mixed media on transfer functions with a pacemaker system for estimation of RF heating during MRI scans. Comput Cardiol 44(1–4):5
Bottomley PA, Kumar A, Edelstein WA, Allen JM, Karmarkar PV (2010) Designing passive MRI-safe implantable conducting leads with electrodes. Med Phys 37(7):3828–3843
ASTM F2182 - 11a. Standard test method for measurement of radio frequency induced heating on or near passive implants during magnetic resonance imaging
C95.3–2003: Recommended practice for measurements and computations with respect to human exposure to radiofrequency electromagnetic fields, 100 kHz to 300 GHz. Institute of Electrical and Electronics Engineers (IEEE).
Lucano E, Liberti M, Mendoza GG, Lloyd T, Iacono MI, Apollonio F, Wedan S, Kainz W, Angelone LM (2016) Assessing the electromagnetic fields generated by a radiofrequency mri body coil at 64 MHz: defeaturing versus accuracy. IEEE Trans Biomed Eng 63(8):1591–1601
Nyenhuis J, Jallal J, Min X, Sison S, Mouchawar G. Comparison of Measurement and Calculation of the Electric Field Transfer Function for an Active Implant Lead in Different Media. Proceedings from the Computing in Cardiology Conference, Sophia Antipolis, France, 2015. pp 765–768.
Mattei E, Calcagnini G, Censi F, Triventi M, Bartolini P (2012) Role of the lead structure in MRI-induced heating: In vitro measurements on 30 commercial pacemaker/defibrillator leads. Magn Reson Med 67(4):925–935
Mattei E, Triventi M, Calcagnini G, Censi F, Kainz W, Bassen HI, Bartolini P (2007) Temperature and SAR measurement errors in the evaluation of metallic linear structures heating during MRI using fluoroptic probes. Phys Med Biol 52(6):1633–1646
Mattei E, Triventi M, Calcagnini G, Censi F, Kainz W, Mendoza G, Bassen HI, Bartolini P (2008) Complexity of MRI induced heating on metallic leads: experimental measurements of 374 configurations. Biomed Eng Online 3(7):11
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Disclosure
The mention of commercial products, their sources, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Mattei, E., Censi, F., Calcagnini, G. et al. A combined computational and experimental approach to assess the transfer function of real pacemaker leads for MR radiofrequency-induced heating. Magn Reson Mater Phy 34, 619–630 (2021). https://doi.org/10.1007/s10334-021-00909-0
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10334-021-00909-0