Research On The Performance Of 3T Magnetic Resonance Rf Receiving Coil Based On Metamaterials

Magnetic resonance imaging(MRI)is an advanced medical imaging technology with the most rapid development in recent 20 years.It has many considerable advantages of no trauma,no radiation,multi parameters,high resolution,high contrast ratio and arbitrary cross section imaging.Radio frequency(RF)receiving coil is used for short distance reception of the weak resonance signals emitted by nuclear in the imaging area.Therefore,the performance of RF receiving coil play a key role in the quality of magnetic resonance imaging by affecting the signal-to-noise ratio(SNR)of the image directly.In order to obtain images with higher SNR which is beneficial to clinical diagnosis,one of the main aspects of research on magnetic resonance system is the study of how to improve the performance of the RF receiving coil.Metamaterial with the extraordinary electromagnetic properties,which nature materials do not have,is a kind of artificial composite material.The metamaterial can have negative permeability,negative permittivity and negative refraction index due to the orderly design of the size and shape of the periodic unit structure.With the specific usage,these properties can be used to enhance the performance of microwave devices.Nowadays,metamaterials have been widely used in the fields of microwave RF,antenna and so on.The main work of this paper are to design metamaterials for 3T MRI RF receiving coils,then study its effect on the performance of the RF receiving coil.Firstly,this paper introduces the background knowledge of the MRI,metamaterial characteristics and field-circuit co-simulation method which can be used to design RF coils.The influence of the negative magnetic permeability of the metamaterial on the RF coil was studied by the numerical simulation method of the electromagnetic field.Then,designed and produced several metamaterials with different frequency by the design method of metamaterial introduced.And their equivalent permeability was extracted by Smith method.The actual measurement,analysis and optimization of the fabricated metamaterials were carried out.Finally,the metamaterials were loaded to the RF receiving coil and the contrast experiments of the 3T MRI water phantom were executed.The comparison results indicate that the signal-to-noise ratio of imagines from the body receiving coil with metamaterial loaded is better than that without metamaterial loaded.But in order to obtain the better experimental results,the water phantom experiments should be further optimized.