1,721,169 research outputs found
Charge relaxation in biological tissues with extremely high permittivity
Full text linkPostprint version of the paper published on IEEE Magnetics Letters
The Misconception of Closed Magnetic Flux Lines
Full text linkThe belief that magnetic flux lines are always closed has been widely disseminated, handed down from Faraday
through the present day. We review the problem and revisit the example of “the wire and the loop,” which shows analytically
that flux lines are not necessarily closed, and extend its analysis. The pictorial representation based on flux lines may give
rise to erroneous conclusions not inherent in Maxwell’s laws
A numerical survey of motion-induced electric fields experienced by MRI operators
No full textThis paper deals with the electric field generated inside the bodies of people moving in proximity to magnetic resonance scanners. Different types of scanners (tubular and open) and various kinds of movements (translation, rotation, and revolution) are analyzed, considering the homogeneous human model proposed in some technical Standards. The computations are performed through the Boundary Element Method, adopting a reference frame attached to the body, which significantly reduces the computational burden. The induced electric fields are evaluated in terms of both spatial distributions and local time evolutions. The possibility of limiting the study to the head without affecting the accuracy of the results is also investigated. Finally, a first attempt to quantify the transient effect of charge separation is proposed
Reply to Comment on Induction of Electric Field in Human Bodies Moving Near MRI: an Efficient BEM Computational Procedure
No full textThe comment written by Cobos Sanchez provides
the occasion to clarify a key point in the development of the formulation proposed in 2011 by the authors. In particular, even
if some Cobos Sanchez’s remarks are theoretically correct, the analysis of the working assumptions shows that they were properly disregarded because insignificant on a practical side
Reply to "Comments on Induction of an Electric Field in Human Bodies Moving Near MRI: An Efficient BEM Computational Procedure"
No full text
A Near-Field Cloaking Study to Reduce MRI RF-Artefacts in Presence of Elongated Prostheses
Full text linkThe objective of this paper is to analyze a near-field electromagnetic cloaking to reduce the radiofrequency (RF) magnetic field inhomogeneities (responsible for the RF-artefacts onset) in magnetic resonance imaging (MRI) in the presence of an elongated metallic hardware. A lumped circuit is considered to explain the role that a dielectric coat has on hiding ametallic cylinder to the RF antenna. The theoretical assumptions are proved by means of full-wave simulations that are also applied to a realistic hip prosthesis considering a frequency equal to 64 and 128 MHz. The numerical results confirm the theoretical assumptions. Both the theoretical analysis and the numerical simulations highlight the different role that the coat thickness and electric permittivity have in the definition of a proper dielectric coat. A particular cloaking approach leads to a dielectric coat whose constitutive electrical parameters may be simple enough to fit the considered application reducing the interaction between an elongated prosthesis and the RF antenna. Furthermore, results obtained at 64 MHz suggest the possibility to employ an existing biocompatible material to achieve the envisaged purposes
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