A Novel Design of Implantable Esophageal Stent to Reduce the MRI RF-Induced Heating

Li, Dawei; Ji, Xiaohe; Zheng, Jianfeng; Pan, Changwang; Chen, Ji; Kainz, Wolfgang

doi:10.1109/temc.2016.2625812

Cited by 11 publications

(3 citation statements)

References 29 publications

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“…Opposite to the p-type Si substrate (11,12) that did not show any image artifacts, the n-type Si substrate generated comparatively high image artifacts (13,14). Pt showed severe image artifacts, regardless of the substrate used (15)(16)(17)(18)(19)(20). All experiments for 7T MRI.…”

Section: Induced Heat and Sarmentioning

confidence: 98%

“…During the past decades, several studies have focused on the safety of implants under MRI with several techniques proposed to overcome the safety issue [ 10 , 14 , 15 , 16 , 17 , 18 , 19 ]. Reported approaches to develop a more MRI compatible neural implant are mainly based on low electrically conductive materials, materials with magnetic susceptibility compatible with tissue, and the shielding of electrodes with high dielectric materials or conductive coils [ 17 , 18 , 20 , 21 , 22 , 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

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Silicon Carbide and MRI: Towards Developing a MRI Safe Neural Interface

et al. 2021

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An essential method to investigate neuromodulation effects of an invasive neural interface (INI) is magnetic resonance imaging (MRI). Presently, MRI imaging of patients with neural implants is highly restricted in high field MRI (e.g., 3 T and higher) due to patient safety concerns. This results in lower resolution MRI images and, consequently, degrades the efficacy of MRI imaging for diagnostic purposes in these patients. Cubic silicon carbide (3C-SiC) is a biocompatible wide-band-gap semiconductor with a high thermal conductivity and magnetic susceptibility compatible with brain tissue. It also has modifiable electrical conductivity through doping level control. These properties can improve the MRI compliance of 3C-SiC INIs, specifically in high field MRI scanning. In this work, the MRI compliance of epitaxial SiC films grown on various Si wafers, used to implement a monolithic neural implant (all-SiC), was studied. Via finite element method (FEM) and Fourier-based simulations, the specific absorption rate (SAR), induced heating, and image artifacts caused by the portion of the implant within a brain tissue phantom located in a 7 T small animal MRI machine were estimated and measured. The specific goal was to compare implant materials; thus, the effect of leads outside the tissue was not considered. The results of the simulations were validated via phantom experiments in the same 7 T MRI system. The simulation and experimental results revealed that free-standing 3C-SiC films had little to no image artifacts compared to silicon and platinum reference materials inside the MRI at 7 T. In addition, FEM simulations predicted an ~30% SAR reduction for 3C-SiC compared to Pt. These initial simulations and experiments indicate an all-SiC INI may effectively reduce MRI induced heating and image artifacts in high field MRI. In order to evaluate the MRI safety of a closed-loop, fully functional all-SiC INI as per ISO/TS 10974:2018 standard, additional research and development is being conducted and will be reported at a later date.

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Section: Induced Heat and Sarmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Silicon Carbide and MRI: Towards Developing a MRI Safe Neural Interface

et al. 2021

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“…Once the safe conditions are determined, the appropriate MR condition can be labeled per ASTM (American Society for Testing and Materials) standards . In literature, work has been conducted to assess the RF‐induced heating for passive implantable medical devices such as stents and orthopedic devices, and active implantable medical devices such as deep brain stimulation systems and cardiac pacemakers . Most passive devices have a single configuration after implantation and can be evaluated using the standard ASTM procedure, and typical MRI safety test results can be found online at http://www.MRIsafety.com.…”

Section: Introductionmentioning

confidence: 99%

Wire‐based sternal closure: MRI‐related heating at 1.5 T/64 MHz and 3 T/128 MHz based on simulation and experimental phantom study

Zheng

Xia

Kainz

et al. 2019

Magnetic Resonance in Med

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Purpose:The paper investigates factors that affect the RF-induced heating for commonly used wire-based sternal closure under 1.5 T and 3 T MRI systems and clarifies the heating mechanisms. Methods: Numerical simulations based on the finite-difference time-domain method and experimental measurements in ASTM (American Society for Testing and Materials) phantom were used in the study. Various configurations of the wire-based sternal closure in the phantom were studied based on parameter sweeps to understand key factors related to the RF-induced heating. In vivo simulations were further performed to explore the RF-induced heating in computational human phantoms for clinically relevant scenarios. Results: The wire-based sternal closure can lead to peak 1-g averaged spatial absorption ratio of 106.3 W/kg and 75.2 W/kg in phantom and peak 1-g averaged specific absorption rate of 32.1 W/kg and 62.1 W/kg in computational human models near the device at 1.5 T and 3 T, respectively. In phantom, the simulated maximum temperature rises for 15-minute RF exposure are 9.4°C at 1.5 T and 5.8°C at 3 T. Generally, the RF-induced heating will be higher when the electrical length of the device is close to the resonant length or when multiple components are spaced closely along the longitudinal direction. Conclusion: The RF-induced heating related to wire-based sternal closure can be significant due to the antenna effect and capacitive mutual coupling effect related to the specific geometries of devices. K E Y W O R D S antenna effect, capacitive mutual coupling effect, magnetic resonance imaging (MRI), RF-induced heating, wire-based sternal closure 1056 | ZHENG Et al.

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