Computational study of external fixation devices surface heating in MRI RF environment

Liu, Yan; Shen, Jiale; Kainz, Wolfgang; Qian, Songsong; Wu, Wen; Chen, Ji

doi:10.1109/isemc.2012.6351691

Cited by 9 publications

(9 citation statements)

References 1 publication

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“…The heating can be related to many factors, e.g. incident tangential electric field distribution, insertion depth of pin inside the ASTM phantom gel and nonconductive material used at the connection part on the device (Liu et al, 2012a). In this study, the device is placed at a location where high incident tangential electric field is observed.…”

Section: Devicementioning

confidence: 99%

“…The connection bar has a diameter of 1.1 cm and a length of 41.5 cm. From a previous study (Liu et al, 2012a), four different insertion depths are used and a shallow insertion of 2 cm is found to produce the highest RF heating. In this study, the 2 cm insertion depth is used for all studies.…”

Section: Devicementioning

confidence: 99%

“…However, this is not applicable to the external fixation devices. The heating mechanism for external fixation device is much more complex (Liu et al, 2012a). The heating can be related to many factors, e.g.…”

Section: Devicementioning

confidence: 99%

“…The device is generally composed by clamps, pins and connection bars. A generic external fixator model was developed to study the clamp spacing, insertion depth and connection bar material effect on the RF heating in MRI environment (Liu et al, 2012a). The model is shown in Figure 4.…”

Section: Devicementioning

confidence: 99%

“…Liu et al studied the effect of clamp spacing, insertion depth and bar material properties on MRI RF-induced heating for external fixation devices. Shorter insertion depth, longer clamp spacing and metallic connection bar are found to contribute to the high temperature rise at the tip of pin on devices (Liu et al, 2012a). Even when the exposure levels are below the thermal limits, there still can be potential tissue damage (1998).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Effect of insulating layer material on RF-induced heating for external fixation system in 1.5 T MRI system

Liu

Kainz

Qian

et al. 2013

Electromagnetic Biology and Medicine

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The radio frequency (RF)-induced heating is a major concern when patients with medical devices are placed inside a magnetic resonance imaging (MRI) system. In this article, numerical studies are applied to investigate the potentials of using insulated materials to reduce the RF heating for external fixation devices. It is found that by changing the dielectric constant of the insulation material, the RF-induced heating at the tips of devices can be altered. This study indicates a potential technique of developing external fixation device with low MRI RF heating.

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Section: Devicementioning

confidence: 99%

Section: Devicementioning

confidence: 99%

Section: Devicementioning

confidence: 99%

Section: Devicementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of insulating layer material on RF-induced heating for external fixation system in 1.5 T MRI system

Liu

Kainz

Qian

et al. 2013

Electromagnetic Biology and Medicine

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Reducing MRI RF-induced heating for the external fixation using capacitive structures

et al. 2020

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This paper presents a generic method to reduce the radiofrequency (RF) induced heating of external fixation devices during the magnetic resonance imaging (MRI) procedure. A simplified equivalent circuit model was developed to illustrate the interaction between the external fixation device and the MRI RF field. Carefully designed mechanical structures, which utilize capacitive reactance from the circuit model, were applied to the external fixation device to mitigate the coupling between the external fixation device and the MRI RF field for RF-induced heating reduction. Both numerical and experimental studies were performed to demonstrate the validity of the circuit model and the effectiveness of the proposed method. By adding capacitive structures in both the clamp-pin and rod-clamp joints, the peak specific absorption rate averaged in 1 gram (SAR1g) near the pin tips were reduced from 760.4 W kg−1 to 12.0 W kg−1 at 1.5 T and 391.5 W kg−1 to 25.2 W kg−1 at 3 T from numerical simulations. Experimental results showed that RF-induced heating was reduced from 7.85 °C to 1.01 °C at 1.5 T and from 16.70 °C to 0.32 °C at 3 T for the external fixation device studied here. The carefully designed capacitive structures can be used to detune the coupling between the external fixation device and the MRI fields to reduce the RF-induced heating in the human body for both 1.5 T and 3 T MRI systems. However, as RF-induced heating is very device and design specific all devices must be thoroughly tested based on its final design.

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MRI heating reduction for external fixation devices using absorption material

Huang

Zheng

Chen

et al. 2014

2014 IEEE International Symposium on Electromagnetic Compatibility (EMC)

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Using absorption materials to reduce RF heating during MRI procedure is studied in this paper. Materials with different electromagnetic absorption characteristics are used to alter the EM and current distributions on the device. Consequently, the RF induced heating behaviors of external fixation devices can be reduced. Numerical and experimental studies are provided to demonstrate the potentials of reducing the RF heating for external fixation devices of using lossy materials.

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Computational study of external fixation devices surface heating in MRI RF environment

Cited by 9 publications

References 1 publication

Effect of insulating layer material on RF-induced heating for external fixation system in 1.5 T MRI system

Effect of insulating layer material on RF-induced heating for external fixation system in 1.5 T MRI system

Reducing MRI RF-induced heating for the external fixation using capacitive structures

MRI heating reduction for external fixation devices using absorption material

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