MRI拉莫尔频率范围内人体脑胶质瘤组织的介电特性

Dielectric properties of human glioma tissue at Larmor frequencies in MRI

目的:研究人体脑胶质瘤组织在MRI拉莫尔频率范围内(50~500 MHz)的介电特性,建立人体脑胶质瘤组织介电参数频率谱图,为磁共振断层成像技术提供理论依据和数据参考。方法:以神经外科手术中切下的脑胶质瘤组织为标本,在温度为37°C的恒温水箱中,利用开端同轴线法,在50~500 MHz频率范围内使用AV 3656A网络分析仪测量脑胶质瘤组织标本的介电特性。以四阶Cole-Cole模型为基础,利用最小二乘曲线拟合方法,提取人体脑胶质瘤组织的介电特征参数。同时,将实验测得的脑胶质瘤组织介电特性与健康人体组织介电特性数据库中的正常脑组织进行比较。结果:在测频率范围内,人体脑胶质瘤组织实测数据与Cole-Cole模型吻合良好,且有人体脑胶质瘤组织的相对介电常数比正常脑组织高29.5%~36.6%,电导率比正常脑组织高56.1%~64.8%。结论:本文报道了37°C下人体脑胶质瘤组织在MRI拉莫尔频率范围内(50~500 MHz)的介电特性数据及相应的Cole-Cole模型介电特征参数,可为人体脑胶质瘤组织介电特性研究和磁共振断层成像技术提供基础数据。

Objective To investigate the dielectric properties of human glioma tissue at Larmor frequencies in MRI(50-500 MHz)and to establish the dielectric parameter frequency spectrum of human glioma tissue,thereby providing theoretical basis and reference data for magnetic resonance electrical property tomography(MREPT).Methods The glioma tissue which was removed from the brain during neurosurgery was taken as specimen.In a thermostatic water container with the temperature controlled at 37°C,open-ended coaxial line method was used to measure the dielectric properties of human glioma tissue specimen via AV 3656A network analyzer at the frequencies between 50 MHz and 500 MHz.The dielectric characteristic parameters of human glioma tissue were obtained by the least square curve fitting method based on fourthorder Cole-Cole model.Finally,the dielectric properties of glioma tissue which were measured in the experiment were compared with those of normal brain tissue in a healthy human tissue dielectric property database.Results The measured data were fit closely with Cole-Cole model at the frequencies.The relative dielectric constant of human glioma tissue was 29.5%-36.6%high than that of the normal tissue;and the conductivity was 56.1%-64.8%higher than that of normal tissue.Conclusion The dielectric properties of human glioma tissue are measured at Larmor frequencies in MRI(50-500 MHz)at 37°C,and the dielectric characteristic parameters of the corresponding Cole-Cole model are also obtained in the study,which provide basic data for the research on the dielectric properties of human glioma tissue and MREPT.