Abstract
In this work, we experimentally demonstrate an increase in the local transmit efficiency of a 1.5 T MRI scanner by using a metasurface formed by an array of brass wires embedded in a high permittivity low loss medium. Placement of such a structure inside the scanner results in strong coupling of the radiofrequency field produced by the body coil with the lowest frequency electromagnetic eigenmode of the metasurface. This leads to spatial redistribution of the near fields with enhancement of the local magnetic field and an increase in the transmit efficiency per square root maximum specific absorption rate in the region-of-interest. We have investigated this structure in vivo and achieved a factor of 3.3 enhancement in the local radiofrequency transmit efficiency.
Highlights
Nazarian et al [1] have reported that the likelihood of a patient with an implanted medical device requiring an MRI scan is more than 75%
The presence of medical implants often results in scans with low specific absorption rate (SAR) being prescribed, which reduces the diagnostic quality of the images
In many cases the imaging region-of-interest is different from the area in which the medical device is implanted, or in which electrical leads to the medical device are located
Summary
Nazarian et al [1] have reported that the likelihood of a patient with an implanted medical device requiring an MRI scan is more than 75%. In many cases a patient who would be scanned at 3 T in the absence of an implant is moved to a 1.5 T system since the power deposited in the patient is lower: again this process is accompanied by lower image quality. In many cases the imaging region-of-interest is different from the area in which the medical device is implanted, or in which electrical leads to the medical device are located. In these cases the SAR issues can potentially be overcome if a local transmit coil rather than the body coil could be used. With a few exceptions (e.g. head and knee) there are very few local transmit coils which are produced commercially, and many sites do not have even those
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
