肺部磁共振成像研究

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1、上海交通大学硕士学位论文肺部磁共振成像研究姓名：姚志萍申请学位级别：硕士专业：生物医学工程指导教师：任秋实20070201同的磁场条件下3Hc和129Xc的拉莫尔进动频率不同于1H,故本文运用毕奥-萨伐尔定律，利用IDL软件进行相关计算和仿真，提出惰性气体工作频率下磁共振射频线圈的设计及仿真方案，仿真结果证明了在低场条件下所设计的笼式高通线圈产生的射频磁场的均匀性和对称性。但是，对惰性气体进行光学超极化抽运的工艺复杂，需要的光学设备和真空设备比较昂贵，而且，进行磁共振成像时需要特殊制备的磁共振线圈等硬件设备，限制了这项

2、技术的推广和应用。本文提出的对比度增强剂雾化吸入肺部磁共振成像方法可以成为一种经济、实用、可操作性强的肺部MRI诊断方法。主要是通过超声雾化的方法使磁共振对比度增强剂溶液以极小液滴的形式，经雾化吸入后分散到肺部细支气管和肺泡内，通过对比度增强剂的增强作用，提高肺部的磁共振信号，获得清晰的肺部磁共振图像。关键词：磁共振成像，超极化，笼式线圈，对比度增强剂，超声雾化RESEARCHONMAGNETICRESONANCEIMAGINGOFLUNGABSTRACTMagneticresonanceimaging(MRI)isa

3、newtomographytechnologyfollowedCT,Bultrasonicandotherimagingdiagnosismethods.Themagneticresonancesignalisproportionaltonucleardensity,magneticmomentandpolarizationratio.Conventionalmagneticresonanceimagingusesthehighintensityofprotonsinorganism.Buttheintensityof

4、protonsinlungisjustonetenthofthatofothertissues,soitpresentsgreatchallengetoconventionalmagneticresonanceimagingtechnique・ConsideringthepresentdifficultiesoflungMRI,andinordertoimprovetheresolvingrateofthelungtissueswhenimaging,wedoresearchesontheenhancedlungMRI

5、methodsandtherelatedtechnologies.Noblegaseswithanuclearspinl/2(3He,129Xe)canbehyperpolarizedbyopticalpumping・Hyperpolarizationresultsinanon-equilibriumpolarizationwhichisfiveordersofmagnitudehigherthanBoltzmannthermalequilibrium,andthisresultingmagnetizationcanb

6、eusedasaprobeformagneticresonanceimaging.Thistechniqueimagesnoblegaseswithhighpolarizationaftertheinhalationofhyperpolarizednoblegas.Inordertoincreasethehyperpolarizationefficiency,weputforwardameliorationsofthehyperpolarizedgasproducingapparatusonthebasisofawho

7、lestudyofhyperpolarizednoblegaslungMRLTheninordertogetexactparametersoftheMRIsystem,aperformancesmeasurementapparatusfortheMRIsystemisdesigned・BecausetheLarmorprecessionratesorresonantfrequenciesof3He,129Xearedifferentfromthatof1Hevenatthesamemagneticfield,weapp

8、lyBiot-Savart^slawandIDLsoftwaretocalculateandsimulateourschemetobringforwarddesignandsimulationofthebirdcagecoilswhoseresonantfrequencywasconsistentwithhyperpolarize