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2 results on '"Sécurité IRM"'

1. Finite Difference Transmission Line model for the design of safe multi-sections cables in MRI

Author

Missoffe, Alexia, Imagerie Adaptative Diagnostique et Interventionnelle (IADI), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lorraine (UL), Région LorraineFEDER, SpinE, Université de Lorraine (UL)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Missoffe, Alexia

Subjects
phase effects, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, MRI safety, [MATH.MATH-NA] Mathematics [math]/Numerical Analysis [math.NA], Radiofréquence, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, radiofrequency, cables, transfer function, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], [MATH.MATH-AP] Mathematics [math]/Analysis of PDEs [math.AP], sécurité IRM, pacemaker leads, [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract

Purpose: To show the relevance of a simple finite difference transmission line model for help in the design of safe cables in 1.5 T MRI’s using the multi-section cable approach. Methods: A two section wire will be studied as a function of the length of the two different sections. The result concerning the heating of the electrodes for a constant electrical field excitation along the wire as well as the estimation of the correction phase factor will be compared to full-wave simulation results. Such information allows estimation of the worst case heating of the cable in MRI taking into account the phase effects.Results: The transmission line predicts correctly the full-wave simulation results. The optimum length of the second section reduces by 37% the worst case heating at the electrode compared to the best case unique section wire.Conclusion: The multi-section cable design can reduce the heating of cables in MRI taking into account the phase effects. The finite difference transmission line model presented is a simple valuable tool to estimate the worst case heating of multi-section cables thus helping to optimize the design of such cables.

Published
2017

2. New transmission line model of an insulated cable embedded in gel for MRI radiofrequency interaction hazard evaluation as an alternative to the transfer function model

Author

Alexia Missoffe, Julie Kabil, Pierre-André Vuissoz, jacques Felblinger, Missoffe, Alexia, Imagerie Adaptative Diagnostique et Interventionnelle (IADI), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lorraine (UL), Centre d'investigation clinique [Nancy] (CIC), Université de Lorraine (UL)-Centre Hospitalier Régional Universitaire de Nancy (CHRU Nancy)-Institut National de la Santé et de la Recherche Médicale (INSERM), Service de Radiologie et Echographie [CHRU Nancy], Centre Hospitalier Régional Universitaire de Nancy (CHRU Nancy), Région LorraineFEDER, SpinE, Université de Lorraine (UL)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Centre Hospitalier Régional Universitaire de Nancy (CHRU Nancy)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lorraine (UL)

Subjects
Ligne de transmission, [SPI.ELEC] Engineering Sciences [physics]/Electromagnetism, MRI safety, heating, transmission line, Sécurité IRM, [MATH.MATH-NA] Mathematics [math]/Numerical Analysis [math.NA], pacemaker, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, radiofrequency, Radiofréquences, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], transfer function, [MATH.MATH-AP] Mathematics [math]/Analysis of PDEs [math.AP], [MATH.MATH-NA]Mathematics [math]/Numerical Analysis [math.NA]
Abstract

Object: To demonstrate the possibility to model the power deposited at the electrode of an insulated cable in gel at 64MHz with a transmission line model with a strictly passive electrode model. This offers a more related to physics alternative to the transfer function model. The equivalence between both models is shown.Materials and Methods: In a first step, the possibility of modeling an insulated cable with a transmission line model was analyzed through full-wave numerical simulations. An electrode model that has a physical meaning was proposed. The transmission line model predictions were confronted to experimental and simulated data of the transfer function of a cable and of the resonant behavior as a function of length of cables with different termination conditions.Results: The assumption of a transmission line model which underlies the transfer function model is right for a simple cable embedded in tissue imitating gel. A transmission line model extracted from a transfer function allows to predict the resonant behavior of two cables with different termination conditions.Conclusion: A transmission line model of an insulated cable embedded in tissue imitating gel offers a more directly related to physics alternative to the transfer function model.

Published
2017

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