MRI‐based transfer function determination for the assessment of implant safety

Purpose We introduce a new MR‐based method to determine the transfer function (TF) for radiofrequency (RF) safety assessment of active implantable medical devices. Transfer functions are implant‐specific measures that relate the incident tangential electric field on an (elongated) implant to a scatt...

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Vydáno v:Magnetic resonance in medicine Ročník 78; číslo 6; s. 2449 - 2459
Hlavní autoři: Tokaya, J.P., Raaijmakers, A.J.E., Luijten, P.R., Bakker, J.F., Berg, C.A.T.
Médium: Journal Article
Jazyk:angličtina
Vydáno: United States Wiley Subscription Services, Inc 01.12.2017
Témata:
active implantable medical device (AIMD)
Adaptation
Animals
Computer Graphics
Computer Simulation
Correlation coefficients
Data acquisition
Deep Brain Stimulation
Electric fields
Electromagnetic Fields
Electromagnetic Radiation
Elongation
EM simulations
Humans
Image Processing, Computer-Assisted
Magnetic Fields
Magnetic Resonance Imaging
Medical devices
Medical equipment
Phantoms, Imaging
Prostheses and Implants
Radio frequency
Radio Waves
Reciprocity
Reproducibility of Results
RF heating
Safety
Signal-To-Noise Ratio
Spatial discrimination
Spatial resolution
Surgical implants
transfer function
Transfer functions
Transplants & implants
transfer function
active implantable medical device (AIMD)
EM simulations
RF heating
safety
ISSN:0740-3194, 1522-2594, 1522-2594
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Shrnutí:Purpose We introduce a new MR‐based method to determine the transfer function (TF) for radiofrequency (RF) safety assessment of active implantable medical devices. Transfer functions are implant‐specific measures that relate the incident tangential electric field on an (elongated) implant to a scattered electric field at its tip. The proposed method allows for TF determination with a high spatial resolution in relatively fast measurements without requiring dedicated bench setups from MRI images. Theory and Methods The principle of reciprocity is used in conjunction with the potential to measure currents with MRI to determine TF. Low‐flip angle 3D dual gradient echo MRI data are acquired with an implant as transceive antenna, which requires minimal hardware adaptations. The implant‐specific TF is determined from the acquired MRI data, with two different postprocessing methods for comparison. Results TFs of linear and helical implants can be determined accurately (with a Pearson correlation coefficient R ≥ 0.7 between measurements and simulations, and a difference in field at the tip ΔEtip ≤ 19%) from relatively quick (t < 20 minutes) MRI acquisitions with (several) millimeter spatial resolution. Conclusion Transfer function determination with MRI for RF safety assessment of implantable medical devices is possible. The proposed MR‐based method allows for TF determination in more realistic exposure scenarios and solid media. Magn Reson Med 78:2449–2459, 2017. © 2017 International Society for Magnetic Resonance in Medicine
Bibliografie:The copyright line for this article was changed on 20 July 2017 after original online publication.
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ISSN:0740-3194
1522-2594
1522-2594
DOI:10.1002/mrm.26613