超极化惰性气体磁共振肺部成像

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1、上海交通大学硕士学位论文超极化惰性气体磁共振肺部成像姓名：魏石岗申请学位级别：硕士专业：生物医学工程指导教师：任秋实20060120术而在仍然保持高场系统的信噪比和图像分辨率的情况下提供一种更为经济的成像方式31291He和Xe的核磁矩不同于H这意味着在相同的磁场强度31291下He和Xe的拉莫尔进动频率或共振频率不同于H所以有必要对射频RFRadioFrequency系统进行一些硬件改装超极化惰性气体MRI系统性能测试装置可以方便而又快速地测试系统的各项参数本文给出了超极化装置的设计方法用于具有非平衡性

2、质超极化磁化特殊成像脉冲序列设计的一般考虑以及使用超极化惰性气体的磁共振成像系统性能参数测量装置的设计方法关键字超极化光泵核自旋磁共振成像IIHYPERPOLARIZEDNOBLEGASESMAGNETICRESONANCEIMAGINGOFTHELUNGABSTRACTConventionalmagneticresonanceimaging(MRI)isanon-invasive,non-ionizingimagingtechnique,theadvantageliesinitsminimalpatie

3、ntrisk,excellentsofttissuecontrast,andmulti-planarimaging.Itimages1thehydrogennuclei,orprotons(H)usingthehighintensityofprotonsinourbodies.Butforsometissues,suchasthelung,theintensityofprotonsisjustonetenthofthatofothertissues,soitpresentsgreatchallengeto

4、conventionalmagneticresonanceimagingtechnique.TheMRItechniqueusinghyperpolarizednoblegaseshasbeenprovedtobeapromisingtoolforthelungimagingsinceitsdemonstrationin1994.3129Noblegaseswithanuclearspin1/2(He,Xe)canbehyperpolarizedbyopticalpumping.Polarizationi

5、stransferredfromcircularlypolarizedlaserlighttothenoblegasatomsviaalkalimetalvapors(spinexchange).Hyperpolarizationresultsinanon-equilibriumpolarizationfiveordersofmagnitudehigherthantheBoltzmannthermalequilibrium,thisresultingmagnetizationcanbeusedasapro

6、beformagneticresonanceimaging.DifferentfromtheconventionalMRItechnique,thistechniqueimageshyperpolarizednoblegasesusingthehighpolarizationofhyperpolarizednoblegases.ThehyperpolarizednoblegasesMRIcanbeperformedatmuchlowermagneticfieldstrength,thereforeprov

7、idingamoreeconomicalIIIalternativetomagneticresonanceimagingbyreplacinghighfield(1.5T)superconductingmagnettechnologywithlowfield(150G)resistiveorpermanentmagnets,whilestillmaintainingthesignal-to-noiseratioandimageresolutionofahighfieldsystem.3129Thenucl

8、earmagneticmomentsofHe,Xearedifferentfromthat13ofH.ThismeansLarmorprecessionratesorresonantfrequenciesofHe,1291XearedifferentfromthatofHevenatthesamemagneticfieldstrength.SomehardwareadjustmentsoftheRFsystemneeded.T