On the Relationship Between Impedances of Active Implantable Medical Devices and Device Safety Under MRI RF Emission

Liu, Jingshen; Jackson, David R.; Wang, Qingyan; Kainz, Wolfgang; Chen, Ji

doi:10.1109/temc.2019.2938908

Cited by 8 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…and for different TSMs, for RF-induced voltage at the proximal end. While this work did not focus on RF-induced heating, it is still important for any discussion of the impact of TSM properties to highlight the influence of the tip impedance, Z tip , on the ultimate result, a relationship which has been explored in further depth [37]. Still, neither of these works investigated which TSM would then give the most accurate result when compared to a full evaluation with an inhomogeneous CHM.…”

Section: Numerical Studies Of Simplified Structuresmentioning

confidence: 99%

RF-induced Heating Near Active Implanted Medical Devices in MRI: Impact of Tissue Simulating Medium

Brown

Stadnik

Arx

et al. 2022

Brain and Human Body Modelling 2021

View full text Add to dashboard Cite

Recent advances in the MR conditional safety assessment of active implantable medical devices (AIMDs) have begun providing guidelines in the development of transfer functions for evaluating risk to the patient due to RF-induced heating. This work introduces the complexity of the analysis of RF-induced heating and explores the impact of the computational human model (CHM) on the resulting analysis. Through historical analysis techniques, simplified structures, and real medical device geometries, the interaction of the AIMD lead with the tissue simulating medium (TSM) can be better understood. Finally, a general guiding principle for MR manufacturers is identified, whereby the thickness of the lead insulation can be used to determine the appropriate TSM for the most accurate in vivo predictions of RF-induced heating.

show abstract

Section: Numerical Studies Of Simplified Structuresmentioning

confidence: 99%

RF-induced Heating Near Active Implanted Medical Devices in MRI: Impact of Tissue Simulating Medium

Brown

Stadnik

Arx

et al. 2022

Brain and Human Body Modelling 2021

View full text Add to dashboard Cite

show abstract

“…RF heating is evaluated at the distal end of the lead, while RF-induced energy is quantified at the proximal end, but otherwise the phenomena are very much related. Both may be influenced differently by the terminating impedance at the IPG [12].…”

Section: Evaluation Of Rf-induced Unintended Stimulation Using Computmentioning

confidence: 99%

RF-Induced Unintended Stimulation for Implantable Medical Devices in MRI

Brown

Qiang

Stadnik

et al. 2020

Brain and Human Body Modeling 2020

View full text Add to dashboard Cite

Historically, patients with implantable medical devices have been denied access to magnetic resonance imaging (MRI) due to several potentially hazardous interactions. There has been significant interest in recent years to provide access to MRI to patients with implantable medical devices, as it is the preferred imaging modality for soft tissue imaging. Among the potential hazards of MRI for patients with an active implantable medical device is radio frequency (RF)-induced unintended stimulation. RF energy incident on the device may be rectified by internal active components. Any rectified waveform present at the lead electrodes may stimulate nearby tissue. In order to assess the risk to the patient, device manufacturers use computational human models (CHMs) to quantify the incident RF on the device and perform in vitro testing to determine the likelihood of unintended stimulation. The use of CHMs enables the investigation of millions of scenarios of scan parameters, patient sizes and anatomies, and MR system technologies.

show abstract

“…Many studies have investigated the impact of the IPG impedance on the RF-induced heating. An analytical model of the MRI RF-induced lead heating as a function of the impedance at the extremities of AIMD (respectively the lead Tip and the IPG circuit load) has been derived and validated through measurements and simulations for simple structures by Liu et al 5 The dependency of the temperature at the lead tip hotspot on the IPG load impedance has been presented by Guo et al 6 Several authors have been interested in abandoned leads. [7][8][9] Wang et al 7 have recently investigated the RF lead heating of abandoned leads and shown that it depends on the lead proximal termination.…”

Section: Introductionmentioning

confidence: 99%

MRI conditional safety of mixed systems: Study of the impact of active implant medical device impedance on the radiofrequency‐induced lead heating

Fall¹,

Guraliuc²,

Monfret³

et al. 2023

Magnetic Resonance in Med

View full text Add to dashboard Cite

Purpose The aim of this paper is to study the impact of pulse generator small impedance variations on the overall radiofrequency (RF)‐induced heating of a cardiac rhythm management (CRM) lead in a 1.5 T MR system. Methods An analysis was conducted on two CRM pacing leads with different structural designs. The leads were connected to three CRM devices belonging to different technological platforms: two pacemakers and a cardiac resynchronization therapy defibrillator (CRT‐D). All pulse generators had a small (< 5%$$ 5\% $$) RF input impedance compared to the overall system (pulse generator and lead) impedance. In addition, two Dummy load devices with an input impedance that is not negligible compared to the lead impedance were also studied. The implantable systems were studied in terms of RF deposited power at the lead electrodes, which is proportional to the RF‐induced heating. Results Results show that both leads behave very similarly in terms of RF deposited power for the same in‐vivo tangential E‐field excitation when mounting any of the pulse generators; reported differences are well below the combined uncertainty false(k=1false)$$ \left(k=1\right) $$. On the other hand, both Dummy load devices resulted in a RF deposited power which differs from the other pulse generators by values larger than the combined uncertainty. Conclusion The results of our experimental analysis show that different pulse generators would not change the RF‐induced heating behavior of a given lead, provided that the pulse generator impedances are small (in our study less than 5%) compared to the overall system impedance.

show abstract

On the Relationship Between Impedances of Active Implantable Medical Devices and Device Safety Under MRI RF Emission

Cited by 8 publications

References 0 publications

RF-induced Heating Near Active Implanted Medical Devices in MRI: Impact of Tissue Simulating Medium

RF-induced Heating Near Active Implanted Medical Devices in MRI: Impact of Tissue Simulating Medium

RF-Induced Unintended Stimulation for Implantable Medical Devices in MRI

MRI conditional safety of mixed systems: Study of the impact of active implant medical device impedance on the radiofrequency‐induced lead heating

Contact Info

Product

Resources

About