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Offline impedance measurements for detection and mitigation of dangerous implant interactions: an RF safety prescreen. | LitMetric

AI Article Synopsis

Article Abstract

Purpose: The concept of a "radiofrequency safety prescreen" is investigated, wherein dangerous interactions between radiofrequency fields used in MRI, and conductive implants in patients are detected through impedance changes in the radiofrequency coil.

Theory: The behavior of coupled oscillators is reviewed, and the resulting, observable impedance changes are discussed.

Methods: A birdcage coil is loaded with a static head phantom and a wire phantom with a wire close to its resonant length, the shape, position, and orientation of which can be changed. Interactions are probed with a current sensor and network analyzer.

Results: Impedance spectra show dramatic, unmistakable splitting in cases of strong coupling, and strong correlation is observed between induced current and scattering parameters.

Conclusions: The feasibility of a new, low-power prescreening technique has been demonstrated in a simple phantom experiment, which can unambiguously detect resonant interactions between an implanted wire and an imaging coil. A new technique has also been presented which can detect parallel transmit null modes for the wire.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4162873PMC
http://dx.doi.org/10.1002/mrm.25202DOI Listing

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