Research On Performance Of Nuclear Magnetic Resonance Radio Frequency Probe Based On Magnetic Plasma Surface Metamaterial

Magnetic resonance imaging(MRI)is an advanced medical modality aiming to excite the in vivo atoms and perceive their responses ex vivo with radiofrequency(RF)coils.The quality of images is subject to the abundance of target atoms,the power of exciting coils,and the sensitivity of receiving coils,etc.In practice,the abundance of target atoms is application specific,and the power of RF excitation is limited by the specific absorption rate(SAR).It is thus a long-standing topic in the field of MRI study to improve efficiency and resolution.The RF coil is one of key components of MRI,and its performance is thus of vital importance for high signal-to-ratio(SNR),spatial resolution and penetration depth imaging.We designed a metamaterial magneticinductive lens(MIL)with negative permeability which can realize the effective magnetic surface plasmons(MSPs)for magnetic resonance imaging(MRI).Surface plasmon polaritons(SPP)technology is widely used in the study of binding specificity,antibody quality control,antibody selection,drug discovery,cell signaling biomarkers,affinity chromatography,etc.The MIL with negative permeability have been fabricated that is able to amplify evanescent harmonics of the B1 field which is excited by the RF coils at the Larmor frequency 297.2MHz.The first experimental results of MRI using MIL showed that SNR are enhanced about 80% in the sagittal images at the distance 25 mm with a small water phantom.The second experimental results of MRI are enhanced about 260% in the sagittal images and 62% in the axial images at the distance 28 mm with a small water phantom.The third experimental result of MRI are enhanced about 58% in the coronal image at the distance 15 mm with a large water phantom.It means that the metamaterial MIL is useful to improve the spatial resolution of MRI resulting from the capability of concentrating the magnetic field of the surface coil.In summary,metamaterial MILs provide a potential analysis tool to ultra-sensitive MRI that would be promising in neuroimaging,ophthalmoimaging and other kinds of emerging applications.