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MRA及Keyhole匙孔技术

来源: 南方日报网络版     时间: 2019年03月22日 12:55:01
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(原)(标)(题)(:4DMRA及)(Keyhole匙)(孔)(技)(术)(<br />宇)(宙)(的)(奥)(妙)(无)(穷)(无)(尽)(,最)(近)(的)(很)(多)(科)(幻)(电)(影)(,科)(幻)(小)(说)(,围)(绕)(着)(高)(维)(度)(展)(开)(一)(些)(遐)(想)(及)(讨)(论)(。如)(果)(我)(们)(人)(类)(能)(够)(体)(验)((或)(者)(观)(察)(到)()更)(高)(的)(维)(度)(,那)(么)(就)(能)(发)(挥)(更)(大)(的)(潜)(能)(。<br />其)(实)(,想)(一)(想)(,医)(学)(影)(像)(学)(也)(就)(是)(将)(我)(们)(肉)(眼)(可)(能)(无)(法)(直)(接)(观)(察)(到)(的)(东)(西)(反)(应)(在)(不)(同)(维)(度)(上)(。比)(如)(,可)(能)(大)(家)(熟)(悉)(的)(二)(维)(超)(声)(、三)(维)(超)(声)(及)(四)(维)(超)(声)(。二)(维)(超)(声)(就)(是)(形)(成)(一)(个)(切)(面)(成)(像)(,也)(就)(是)(二)(维)(图)(像)(;三)(维)(超)(声)(类)(似)(能)(提)(供)(一)(个)(三)(维)(的)(立)(体)(图)(像)(;而)(再)(高)(一)(级)(的)(四)(维)(超)(声)(也)(就)(是)(加)(上)(了)(时)(间)(轴)(的)(三)(维)(超)(声)(或)(者)(叫)(动)(态)(的)(三)(维)(超)(声)(。<br />CT及)(MRI也)(是)(一)(种)(断)(面)((或)(者)(叫)(断)(层)()成)(像)(。我)(们)(今)(天)(要)(讲)(的)(主)(要)(是)(关)(于)(MRA及)(磁)(共)(振)(血)(管)(成)(像)(技)(术)(的)(内)(容)(。<br />1.概)(述)(<br />磁)(共)(振)(血)(管)(成)(像)((MagneticResonanceAngiography,MRA)是)(采)(用)(磁)(共)(振)(的)(方)(式)(,让)(人)(体)(血)(管)(显)(影)(的)(一)(种)(技)(术)(。大)(家)(临)(床)(中)(比)(较)(熟)(悉)(的)(可)(能)(是)(CTA(ComputedTomographyAngiography)技)(术)(,即)(采)(用)(CT方)(式)(进)(行)(血)(管)(成)(像)(。<br />MRA和)(CTA相)(比)(有)(两)(个)(最)(显)(著)(的)(区)(别)((或)(者)(叫)(特)(点)():<br />1.CTA必)(须)(依)(赖)(于)(注)(射)(对)(比)(剂)((打)(药)()来)(显)(示)(血)(管)(,而)(MRA则)(具)(备)(了)(两)(种)(方)(式)(:一)(种)(是)(注)(射)(对)(比)(剂)(的)(,即)(打)(药)(血)(管)(成)(像)(;另)(一)(种)(则)(是)(不)(需)(要)(注)(射)(对)(比)(剂)(,即)(非)(打)(药)(血)(管)(成)(像)(。这)(个)(最)(大)(的)(优)(势)(就)(是)(在)(于)(不)(用)(往)(身)(体)(里)(打)(入)(对)(比)(剂)(了)(,病)(人)(能)(够)(最)(大)(程)(度)(接)(受)(。<br />2.MRA不)(仅)(可)(以)(做)(血)(管)(成)(像)(,还)(能)(利)(用)(一)(些)(技)(术)(进)(行)(血)(流)(速)(度)(的)(测)(定)(。<br />公)(众)(号)(前)(面)(也)(发)(布)(了)(很)(多)(磁)(共)(振)(血)(管)(成)(像)(的)(文)(章)(,大)(家)(可)(以)(点)(击)(下)(面)(查)(看)(链)(接)(:<br />上)(面)(的)(链)(接)(也)(是)(MRA的)(基)(本)(知)(识)(及)(需)(要)(看)(懂)(这)(篇)(文)(章)(的)(一)(些)(参)(考)(。各)(位)(老)(师)(点)(击)(斜)(体)(字)(下)(划)(线)(就)(能)(直)(接)(转)(到)(相)(关)(文)(章)(界)(面)(。<br />2.四)(维)(血)(管)(成)(像)(4DMRA<br />前)(面)(用)(了)(超)(声)(成)(像)(的)(例)(子)(来)(简)(单)(说)(明)(一)(下)(2D、3D及)(4D成)(像)(的)(概)(念)(。同)(理)(,磁)(共)(振)(成)(像)(也)(是)(这)(样)(。2D成)(像)(就)(是)(平)(面)(内)(成)(像)(;3D成)(像)(就)(是)(立)(体)(成)(像)(或)(者)(叫)(容)(积)((体)(积)()成)(像)(;而)(4D成)(像)(就)(是)(在)(3D成)(像)(的)(基)(础)(上)(增)(加)(了)(时)(间)(轴)(,也)(就)(是)(动)(态)(的)(3D成)(像)(,它)(能)(够)(反)(映)(我)(们)(观)(察)(的)(物)(体)(在)(时)(间)(轴)(方)(面)(的)(一)(个)(动)(态)(变)(化)(过)(程)(。<br />磁)(共)(振)(2D和)(3D扫)(描)(序)(列)(的)(区)(别)(<br />我)(们)(为)(什)(么)(要)(做)(4D成)(像)(呢)(?其)(实)(就)(和)(前)(面)(举)(例)(子)(的)(道)(理)(一)(样)(,维)(度)(高)(的)(成)(像)(方)(式)(能)(够)(让)(我)(们)(观)(察)((得)(到)()更)(多)(的)(信)(息)(。<br />我)(们)(大)(部)(分)(影)(像)(成)(像)(是)(采)(用)(断)(面)(成)(像)(的)(模)(式)(,一)(层)(一)(层)(反)(映)(平)(面)(内)(图)(像)(信)(息)(,这)(样)(我)(们)(诊)(断)(医)(生)(要)(把)(一)(个)(部)(位)(的)(影)(像)(信)(息)(阅)(读)(完)(整)(,需)(要)(一)(层)(一)(层)(的)(翻)(阅)(、浏)(览)(图)(像)(来)(进)(行)(判)(断)(,这)(样)(不)(仅)(时)(间)(长)(,而)(且)(比)(较)(离)(散)(,缺)(乏)(整)(体)(感)(,所)(以)(这)(也)(是)(为)(什)(么)(很)(多)(临)(床)(医)(生)(不)(喜)(欢)(看)(一)(层)(一)(层)(图)(像)(,喜)(欢)(看)(三)(维)(重)(建)(后)(的)(立)(体)(图)(或)(者)(叫)(VR图)(;而)(随)(着)(影)(像)(技)(术)(的)(发)(展)(,多)(排)(多)(层)(薄)(层)(容)(积)(CT扫)(描)(机)(3D磁)(共)(振)(成)(像)(,能)(够)(采)(集)(一)(个)(容)(积)(的)(图)(像)(信)(息)(,特)(别)(是)(薄)(层)(高)(分)(辨)(率)(的)(CT扫)(描)(,能)(够)(保)(证)(各)(项)(同)(性)((高)(几)(何)(保)(真)(度)(),通)(过)(MPR(多)(平)(面)(重)(建)(),VR(三)(维)(容)(积)(重)(建)()等)(技)(术)(,得)(到)(高)(分)(辨)(率)(立)(体)(的)(图)(像)(及)(各)(个)(方)(位)(相)(同)(分)(辨)(率)(图)(像)(,这)(样)(给)(影)(像)(科)(医)(生)(及)(临)(床)(医)(生)(提)(供)(更)(多)(的)(信)(息)(,而)(且)(具)(有)(完)(整)(性)(、连)(贯)(性)(及)(整)(体)(感)(。<br />4D成)(像)(则)(把)(在)(3D成)(像)(的)(模)(式)(上)(,再)(上)(升)(了)(一)(个)(高)(度)(。通)(过)(高)(时)(间)(分)(辨)(率)(的)(动)(态)(扫)(描)((有)(些)(专)(家)(把)(它)(称)(为)(电)(影)(扫)(描)(),能)(够)(观)(察)(到)(在)(一)(个)(时)(间)(范)(围)(内)(物)(体)(的)(动)(态)(变)(化)(。这)(种)(方)(式)(非)(常)(适)(合)(于)(进)(行)(血)(管)(成)(像)((流)(入)(、流)(出)()、运)(动)(监)(测)(及)(一)(些)(运)(动)(功)(能)(的)(扫)(描)(。<br />视)(频)(1:4D打)(药)(MRA,动)(态)(反)(映)(血)(管)(情)(况)(<br />视)(频)(2:飞)(利)(浦)(不)(打)(药)(4DASL血)(管)(<br />3.时)(间)(分)(辨)(率)(vs空)(间)(分)(辨)(率)(<br />在)(磁)(共)(振)(的)(世)(界)(里)(,时)(间)(分)(辨)(率)(和)(空)(间)(分)(辨)(率)(,自)(古)(两)(难)(全)(。<br />图)(1:磁)(共)(振)(三)(角)(<br />熟)(悉)(我)(前)(面)(文)(章)(的)(朋)(友)(,一)(定)(对)(这)(个)(图)(不)(陌)(生)(。我)(把)(它)(叫)(做)(磁)(共)(振)(三)(角)(。<br />在)(信)(噪)(比)(一)(定)(的)(情)(况)(下)(,磁)(共)(振)(成)(像)(中)(,时)(间)(分)(辨)(率)(和)(空)(间)(分)(辨)(率)(是)(一)(对)(相)(互)(牵)(制)(、相)(互)(制)(约)(的)(参)(数)(。<br />我)(们)(在)(进)(行)(磁)(共)(振)(成)(像)(的)(时)(候)(,需)(要)(保)(持)(一)(定)(的)(信)(噪)(比)(,否)(则)(图)(像)(噪)(音)(太)(大)(,颗)(粒)(大)(,图)(像)(显)(得)(模)(糊)(,就)(无)(法)(观)(察)(。<br />在)(信)(噪)(比)(相)(对)(一)(定)(的)(情)(况)(下)(,要)(提)(供)(磁)(共)(振)(图)(像)(的)(空)(间)(分)(辨)(率)(,那)(么)(我)(们)(就)(需)(要)(把)(体)(素)(做)(小)(,矩)(阵)(最)(高)(。这)(样)(的)(话)(,势)(必)(造)(成)(扫)(描)(时)(间)(的)(增)(加)(,那)(么)(时)(间)(分)(辨)(率)(就)(会)(下)(降)(。<br />如)(果)(在)(信)(噪)(比)(一)(定)(的)(情)(况)(下)(,要)(保)(证)(高)(时)(间)(分)(辨)(率)(,则)(需)(要)(提)(高)(扫)(描)(速)(度)(及)(加)(快)(图)(像)(采)(集)(,我)(们)(会)(采)(用)(各)(种)(快)(速)(采)(集)(模)(式)(来)(实)(现)(,但)(是)(这)(样)(基)(本)(上)(会)(导)(致)(空)(间)(分)(辨)(率)(的)(下)(降)(。<br />加)(快)(磁)(共)(振)(成)(像)(的)(参)(数)(汇)(总)(--磁)(共)(振)(快)(速)(成)(像)(技)(术)(<br />所)(以)(,磁)(共)(振)(成)(像)(,要)(同)(时)(满)(足)(高)(空)(间)(分)(辨)(率)(及)(高)(时)(间)(分)(辨)(率)(是)(一)(件)(非)(常)(难)(的)(事)(,可)(以)(说)(是)(鱼)(与)(熊)(掌)(,不)(可)(兼)(得)(。<br />要)(解)(决)(这)(个)(问)(题)(,我)(们)(可)(以)(从)(K空)(间)(入)(手)(。<br />4.K空)(间)(、图)(像)(对)(比)(度)(与)(扫)(描)(时)(间)(<br />K空)(间)(是)(MR原)(始)(数)(据)(的)(承)(载)(空)(间)(。为)(了)(便)(于)(大)(家)(理)(解)(,可)(以)(点)(击)(下)(面)(相)(关)(阅)(读)(链)(接)(了)(解)(K空)(间)(的)(基)(本)(知)(识)(。<br />了)(不)(起)(的)(K空)(间)(<br />图)(2:K空)(间)(示)(意)(图)(<br />磁)(共)(振)(在)(完)(成)(对)(图)(像)(信)(号)(的)(采)(集)(以)(后)(,还)(需)(要)(对)(图)(像)(进)(行)(重)(建)(。最)(早)(的)(磁)(共)(振)(成)(像)(,采)(用)(的)(是)(反)(投)(影)(重)(建)(法)(BackProjection。而)(现)(在)(基)(本)(上)(大)(部)(分)(磁)(共)(振)(成)(像)(采)(用)(的)(是)(快)(速)(傅)(里)(叶)(变)(换)(法)(对)(图)(像)(进)(行)(重)(建)(。接)(受)(的)(模)(拟)(信)(号)(经)(过)(数)(字)(转)(换)(后)(成)(为)(数)(字)(信)(号)(被)(储)(存)(在)(一)(个)(临)(时)(的)(空)(间)(里)(,这)(个)(空)(间)(就)(被)(称)(为)(K空)(间)(。<br />当)(带)(有)(空)(间)(定)(位)(编)(码)(信)(息)(的)(MR信)(号)(原)(始)(数)(据)(填)(充)(完)(K空)(间)(以)(后)(,再)(对)(K空)(间)(的)(数)(据)(进)(行)(傅)(里)(叶)(变)(换)((傅)(里)(叶)(逆)(变)(换)(),我)(们)(就)(得)(到)(磁)(共)(振)(信)(号)(在)(空)(间)(上)(的)(频)(率)(分)(布)(,即)(可)(重)(建)(出)(磁)(共)(振)(图)(像)(来)(。<br />要)(完)(成)(完)(整)(的)(成)(像)(,我)(们)(需)(要)(采)(集)((填)(充)()完)(K空)(间)(上)(的)(信)(号)(数)(据)(,这)(样)(的)(话)(,磁)(共)(振)(扫)(描)(的)(时)(间)(就)(和)(K空)(间)(的)(填)(充)(相)(关)(。<br />扫)(描)(时)(间)(=NSA(激)(励)(次)(数)()×相)(位)(编)(码)(步)(级)((步)(数)()×TR<br />这)(个)(只)(是)(一)(个)(粗)(略)(的)(扫)(描)(时)(间)(公)(式)(,当)(然)(根)(据)(不)(同)(序)(列)(:是)(否)(是)(3D序)(列)(、是)(否)(是)(快)(速)(自)(旋)(回)(波)(序)(列)(、是)(否)(会)(拆)(分)(成)(几)(个)(package等)(,会)(略)(微)(不)(同)(。<br />磁)(共)(振)(的)(扫)(描)(时)(间)(就)(基)(本)(上)(和)(NSA,相)(位)(编)(码)(步)(级)(和)(TR等)(参)(数)(成)(正)(比)(。<br />我)(们)(要)(提)(高)(时)(间)(分)(辨)(率)(,就)(必)(须)(缩)(短)(扫)(描)(时)(间)(,那)(么)(就)(要)(减)(少)(TR、或)(者)(减)(少)(NSA、或)(者)(减)(少)(相)(位)(编)(码)(步)(级)(。<br />在)(磁)(共)(振)(血)(管)(成)(像)(中)(,大)(部)(分)(序)(列)(TR都)(非)(常)(短)(,而)(且)(NSA都)(是)(1,所)(以)(我)(们)(要)(加)(快)(速)(度)(就)(只)(能)(从)(相)(位)(编)(码)(步)(级)(入)(手)(。<br />K空)(间)(一)(个)(比)(较)(重)(要)(的)(特)(性)(就)(是)(:K空)(间)(中)(心)(部)(分)(决)(定)(图)(像)(对)(比)(度)(;外)(周)(部)(分)(决)(定)(图)(像)(细)(节)((空)(间)(分)(辨)(率)()。<br />图)(3-4:K空)(间)(特)(性)(及)(图)(像)(特)(点)(<br />对)(于)(打)(药)(血)(管)(成)(像)(,我)(们)(最)(重)(要)(的)(是)(要)(知)(道)(填)(充)(K空)(间)(中)(心)(部)(分)(的)(时)(间)(点)(和)(药)(物)(到)(达)(目)(标)(血)(管)(时)(间)(点)(是)(否)(重)(合)(。<br />我)(们)(能)(否)(利)(用)(K空)(间)(的)(这)(种)(特)(性)(来)(达)(到)(即)(缩)(短)(了)(扫)(描)(时)(间)(,又)(保)(证)(了)(血)(管)(的)(对)(比)(剂)(及)(空)(间)(分)(辨)(率)(呢)(?<br />5.Keyhole技)(术)(<br />图)(5:Center填)(充)(方)(式)(及)(K空)(间)(分)(区)(<br />前)(面)(讲)(了)(K空)(间)(的)(一)(些)(特)(性)(,即)(中)(心)(部)(分)(主)(要)(觉)(得)(图)(像)(的)(对)(比)(度)(;周)(边)(部)(分)(主)(要)(觉)(得)(图)(像)(的)(空)(间)(分)(辨)(率)(。<br />那)(么)(我)(们)(是)(否)(可)(以)(把)(K空)(间)(分)(成)(两)(个)(部)(分)(,即)(中)(心)(部)(分)(和)(周)(边)(部)(分)(。<br />比)(如)(,如)(图)(所)(示)(,我)(们)(要)(做)(打)(药)(的)(动)(脉)(成)(像)(,我)(们)(可)(以)(在)(动)(脉)(期)(时)(间)(点)(优)(先)(将)(采)(集)(到)(的)(信)(号)(填)(充)(K空)(间)(中)(心)(,这)(样)(图)(像)(的)(对)(比)(度)(就)(以)(动)(脉)(血)(管)(显)(示)(为)(主)(;然)(后)(等)(动)(脉)(期)(过)(后)(,到)(达)(静)(脉)(期)(或)(者)(其)(他)(期)(相)(,我)(们)(在)(把)(采)(集)(的)(数)(据)(填)(充)(周)(边)(,这)(样)(对)(比)(度)(还)(是)(以)(动)(脉)(血)(管)(为)(主)(,但)(是)(K空)(间)(周)(边)(部)(分)(的)(数)(据)(也)(有)(采)(集)(了)(,所)(以)(空)(间)(分)(辨)(率)(也)(能)(够)(保)(证)(。我)(们)(把)(这)(种)(K空)(间)(填)(充)(方)(法)(叫)(做)(CENTER填)(充)(,及)(中)(心)(部)(分)(优)(先)(填)(充)(,这)(种)(方)(法)(能)(保)(证)(在)(短)(短)(的)(药)(物)(到)(达)(动)(脉)(期)(的)(时)(候)(完)(成)(对)(图)(像)(的)(采)(集)(,形)(成)(良)(好)(的)(动)(脉)(血)(管)(成)(像)(对)(比)(。<br />图)(6:CENTER填)(充)(方)(式)(的)(应)(用)(<br />但)(是)(,这)(种)(速)(度)(还)(远)(远)(不)(够)(,只)(能)(保)(证)(能)(够)(把)(动)(脉)(期)(、门)(脉)(期)(、静)(脉)(期)(拆)(分)(出)(来)((如)(图)(所)(示)(,动)(脉)(期)(18s,门)(静)(脉)(期)(45s,时)(间)(分)(辨)(率)(大)(概)(是)(45-18=27s),离)(实)(现)(4D血)(管)(成)(像)(还)(不)(够)(。<br />我)(们)(如)(果)(要)(做)(4DMRA,就)(必)(须)(要)(保)(证)(,时)(间)(分)(辨)(率)(还)(得)(提)(高)(,也)(就)(是)(说)(扫)(描)(时)(间)(还)(得)(加)(快)(,那)(么)(这)(么)(办)(呢)(?<br />既)(然)(4D血)(管)(成)(像)(的)(时)(候)(,是)(在)(一)(边)(注)(射)(对)(比)(剂)(,一)(边)(采)(集)(图)(像)(。图)(像)(的)(最)(主)(要)(变)(化)(是)(对)(比)(度)(的)(变)(化)(,那)(么)(我)(们)(能)(否)(只)(采)(集)(K空)(间)(中)(心)(部)(分)(的)(数)(据)(,这)(样)(扫)(描)(速)(度)(可)(以)(飞)(速)(的)(提)(高)(,然)(后)(在)(利)(用)(平)(扫)(或)(者)(打)(药)(前)(扫)(描)(的)(一)(个)(完)(整)(的)(目)(标)(血)(管)(图)(像)((这)(个)(图)(像)(K空)(间)(数)(据)(采)(集)(是)(完)(整)(的)(,既)(包)(含)(中)(心)(部)(分)(数)(据)(,也)(包)(含)(周)(边)(部)(分)(数)(据)(),把)(这)(个)(图)(像)(的)(K空)(间)(周)(边)(部)(分)(决)(定)(解)(剖)(细)(节)(的)(数)(据)(提)(取)(出)(来)(,进)(行)(组)(合)(,那)(么)(我)(们)(就)(得)(到)(了)(不)(同)(对)(比)(度)(下)(,同)(一)(个)(目)(标)(血)(管)(的)(不)(同)(动)(态)(图)(像)(。<br />这)(个)(技)(术)(的)(名)(字)(叫)(做)(Keyhole,中)(文)(翻)(译)(为)(匙)(孔)(技)(术)(。我)(觉)(得)(这)(个)(翻)(译)(是)(非)(常)(准)(确)(和)(信)(达)(雅)(的)(。<br />图)(7:匙)(孔)(技)(术)(示)(意)(图)(<br />把)(K空)(间)(分)(成)(两)(部)(分)(,中)(心)(决)(定)(对)(比)(度)(的)(区)(域)(如)(同)(一)(个)(孔)((钥)(匙)(孔)(),不)(同)(钥)(匙)(开)(不)(同)(的)(锁)(。外)(面)(决)(定)(解)(剖)(细)(节)(的)(区)(域)(如)(同)(门)(。不)(同)(门)(的)(区)(别)(就)(是)(钥)(匙)(不)(同)(。也)(就)(是)(说)(,同)(一)(个)(目)(标)(血)(管)(,连)(续)(动)(态)(电)(影)(成)(像)(,他)(们)(的)(主)(要)(区)(别)(是)(对)(比)(度)(不)(同)(,而)(空)(间)(分)(辨)(率)(等)(解)(剖)(信)(息)(变)(化)(不)(大)((只)(要)(病)(人)(不)(大)(移)(动)()。<br />在)(使)(用)(Keyhole技)(术)(中)(,我)(们)(还)(是)(需)(要)(扫)(描)(一)(个)(完)(整)(的)(K空)(间)(数)(据)(图)(像)(,我)(们)(把)(这)(个)(图)(像)(叫)(做)(参)(考)(图)(像)((ReferenceImageorMask),这)(个)(图)(像)(由)(于)(具)(有)(完)(整)(的)(K空)(间)(数)(据)(,可)(以)(给)(后)(面)(的)(图)(像)(提)(供)(周)(边)(的)(K空)(间)(数)(据)(信)(息)(。<br />而)(在)(做)(动)(态)(4D扫)(描)(的)(时)(候)(,我)(们)(只)(需)(要)(采)(集)(每)(个)(动)(态)(的)(K空)(间)(中)(心)(数)(据)(,得)(到)(的)(是)(一)(些)((一)(组)()低)(空)(间)(分)(辨)(率)(高)(时)(间)(分)(辨)(率)(的)(动)(态)(图)(像)(。然)(后)(,我)(们)(把)(高)(时)(间)(分)(辨)(率)(的)(动)(态)(图)(像)(K空)(间)(中)(心)(数)(据)(信)(息)(和)(前)(面)(的)(参)(考)(图)(像)(的)(K空)(间)(周)(边)(数)(据)(信)(息)(相)(组)(合)(,就)(得)(到)(了)(既)(满)(足)(高)(时)(间)(分)(辨)(率)(又)(满)(足)(高)(空)(间)(分)(辨)(率)(的)(图)(像)(。<br />采)(用)(匙)(孔)(技)(术)(为)(什)(么)(能)(够)(大)(幅)(度)(提)(高)(时)(间)(分)(辨)(率)(呢)(?<br />图)(8:Keyhole技)(术)(大)(幅)(度)(缩)(短)(扫)(描)(时)(间)(<br />如)(图)(所)(示)(,如)(果)(我)(们)(只)(采)(集)(K空)(间)(中)(心)(部)(分)(,那)(么)(需)(要)(的)(时)(间)(是)(远)(远)(少)(于)(填)(充)(完)(K空)(间)(所)(有)(部)(分)(的)(。这)(里)(有)(一)(个)(参)(数)(叫)(做)(Keyholepercentage,也)(就)(是)(填)(充)(百)(分)(比)(。如)(果)(我)(们)(只)(填)(充)(16%的)(K空)(间)(比)(例)((K空)(间)(中)(心)(部)(分)(),那)(么)(扫)(描)(速)(度)(就)(提)(高)(了)(100%÷16%≈6,提)(高)(了)(6倍)(的)(速)(度)(。这)(样)(原)(来)(时)(间)(分)(辨)(率)(为)(27s的)(,现)(在)(仅)(仅)(27÷6=4.5s。这)(样)(的)(速)(度)(就)(能)(保)(证)(每)(2-5s完)(成)(整)(个)(目)(标)(血)(管)(扫)(描)(,可)(以)(进)(行)(4D动)(态)(扫)(描)(。<br />图)(9:头)(颅)(血)(管)(4D扫)(描)((4DMRA)<br />上)(图)(是)(对)(一)(个)(头)(颅)(血)(管)(进)(行)(连)(续)(扫)(描)((动)(态)(扫)(描)(),可)(以)(清)(楚)(的)(观)(察)(到)(从)(动)(脉)(流)(入)(到)(静)(脉)(流)(出)(的)(整)(个)(过)(程)(,实)(现)(4DMRA。上)(面)(的)(扫)(描)(速)(度)(有)(多)(快)(呢)(?<br />上)(面)(的)(时)(间)(分)(辨)(率)(是)(0.63s。0.63秒)(什)(么)(概)(念)(啊)(,同)(志)(们)(?就)(是)(不)(到)(1秒)(,就)(完)(成)(对)(整)(个)(3D颅)(脑)(容)(积)(血)(管)(的)(采)(集)(一)(次)(。为)(什)(么)(这)(么)(快)(呢)(,因)(为)(采)(用)(了)(匙)(孔)(技)(术)(及)(SENSE技)(术)(,加)(速)(达)(到)(60倍)(?有)(人)(问)(我)(60倍)(是)(这)(么)(算)(出)(来)(的)(。<br />我)(给)(大)(家)(看)(看)(扫)(描)(参)(数)(。<br />图)(10:4DMRA,0.63s时)(间)(分)(辨)(率)(<br />并)(行)(采)(集)(SENSE给)(的)(是)(8,由)(于)(是)(4DMRA扫)(描)((即)(3D容)(积)(扫)(描)(+多)(动)(态)(扫)(描)(),可)(以)(在)(两)(个)(方)(向)(使)(用)(并)(行)(采)(集)(,即)(2*4=8倍)(。这)(里)(就)(加)(速)(了)(8倍)(。<br />然)(后)(使)(用)(匙)(孔)(技)(术)(,只)(采)(集)(16%的)(K空)(间)(数)(据)(,加)(速)(6倍)(。<br />再)(利)(用)(半)(扫)(描)(技)(术)(,加)(速)(1.25倍)(。<br />合)(计)(:8×6×1.25=60倍)(。<br />目)(前)(主)(流)(的)(三)(家)(公)(司)(GPS都)(有)(匙)(孔)(技)(术)(。<br />飞)(利)(浦)(叫)(做)(:4DTRAK;技)(术)(升)(级)(的)(叫)(4DTRAKXD;<br />GE叫)(做)(:TRICKS;<br />西)(门)(子)(叫)(做)(:TomeResolveMRA。<br />6.匙)(孔)(技)(术)(存)(在)(的)(问)(题)(及)(改)(良)(<br />前)(面)(讲)(了)(匙)(孔)(技)(术)(可)(以)(大)(幅)(度)(提)(高)(扫)(描)(速)(度)(,增)(加)(时)(间)(分)(辨)(率)(,保)(证)(了)(4DMRA的)(可)(能)(。但)(是)(这)(种)(技)(术)(也)(不)(是)(完)(全)(没)(有)(问)(题)(的)(。<br />第)(一)(个)(问)(题)(是)(:由)(于)(我)(们)(需)(要)(扫)(描)(一)(个)(参)(考)(图)(像)(及)(mask图)(,那)(么)(选)(择)(什)(么)(时)(期)(的)(mask图)(会)(影)(响)(图)(像)(的)(对)(比)(。一)(般)(我)(们)(可)(以)(选)(择)(打)(药)(前)(的)(平)(扫)(图)(像)(作)(为)(mask,也)(可)(以)(选)(择)(打)(药)(最)(后)(一)(期)(的)(图)(像)(作)(为)(mask。<br />虽)(然)(K空)(间)(中)(心)(主)(要)(决)(定)(对)(比)(,周)(边)(主)(要)(决)(定)(解)(剖)(细)(节)(,但)(是)(并)(不)(是)(说)(周)(边)(的)(数)(据)(就)(完)(全)(对)(对)(比)(度)(没)(有)(贡)(献)(。<br />我)(们)(发)(现)(,在)(使)(用)(Keyhole技)(术)(的)(时)(候)(,如)(果)(选)(择)(第)(一)(期)((即)(平)(扫)()图)(像)(作)(为)(mask,后)(面)(重)(建)(的)(所)(有)(期)(图)(像)(,都)(相)(对)(血)(管)(没)(有)(那)(么)(亮)((可)(能)(是)(受)(第)(一)(期)(K空)(间)(周)(边)(数)(据)(影)(响)();如)(果)(选)(择)(打)(药)(最)(后)(一)(期)(图)(像)(作)(为)(mask,我)(们)(发)(现)(重)(建)(后)(的)(图)(像)(血)(管)(都)(比)(较)(亮)((包)(括)(平)(扫)(的)(图)(,血)(管)(都)(有)(点)(亮)(,可)(能)(是)(受)(最)(后)(一)(期)(K空)(间)(周)(边)(数)(据)(影)(响)()。所)(以)(,这)(是)(一)(个)(问)(题)(。<br />第)(二)(个)(问)(题)(:虽)(然)(采)(用)(了)(Keyhole技)(术)(,利)(用)(参)(考)(图)(像)(的)(周)(边)(信)(息)(来)(提)(高)(后)(面)(动)(态)(图)(像)(的)(空)(间)(分)(辨)(率)(,但)(是)(由)(于)(后)(面)(的)(动)(态)(图)(像)(仅)(仅)(只)(采)(集)(K空)(间)(中)(心)(部)(分)(数)(据)(,所)(以)(,空)(间)(分)(辨)(率)(相)(对)(还)(是)(没)(有)(扫)(描)(完)(整)(的)(K空)(间)(数)(据)(高)(。<br />如)(何)(克)(服)(这)(个)(问)(题)(?<br />飞)(利)(浦)(采)(用)(改)(良)(后)(的)(4DTRAK序)(列)(,即)(4DTRAKXD。它)(和)(前)(面)(的)(4DTRAK有)(什)(么)(不)(同)(呢)(?<br />图)(11-12:4DTRAK和)(4DTRAKXD示)(意)(图)(比)(较)(<br />和)(4DTRAK不)(同)(的)(是)(,4DTRAKXD在)(进)(行)(后)(面)(的)(动)(态)(采)(集)(的)(时)(候)(,也)(会)(随)(机)(采)(集)(一)(部)(分)(K空)(间)(周)(边)(数)(据)(。这)(样)(的)(话)(,虽)(然)(牺)(牲)(了)(一)(点)(时)(间)(分)(辨)(率)(,但)(是)(大)(幅)(度)(提)(高)(了)(空)(间)(分)(辨)(率)(,而)(且)(克)(服)(了)(前)(面)(第)(一)(个)(问)(题)(。<br />另)(外)(,西)(门)(子)(公)(司)(有)(一)(个)(技)(术)(叫)(SygnoTWIST。这)(个)(序)(列)(也)(是)(用)(来)(做)(4DMRA的)(。<br />图)(13:SygnoTWIST示)(意)(图)(<br />它)(利)(用)(的)(原)(理)(有)(点)(类)(似)(于)(Keyhole,主)(要)(是)(A和)(B交)(替)(的)(采)(集)(,它)(们)(可)(以)(共)(享)(K空)(间)(填)(充)(的)(信)(息)(。<br />7.总)(结)(<br />今)(天)(给)(大)(家)(简)(单)(介)(绍)(了)(一)(下)(磁)(共)(振)(4DMRA序)(列)(及)(Keyhole技)(术)(,希)(望)(对)(大)(家)(有)(所)(帮)(助)(。谢)(谢)(大)(家)(支)(持)(。<br />06th,August2018<br />inHongKong<br />关)(注)(懋)(式)(百)(科)(全)(书)(,分)(享)(更)(多)(的)(精)(彩)(原)(创)(内)(容)(。返)(回)(龙)(虎)(和)(,查)(看)(更)(多)(责)(任)(编)(辑)(:<br />声)(明)(:该)(文)(观)(点)(仅)(代)(表)(作)(者)(本)(人)(,龙)(虎)(和)(号)(系)(信)(息)(发)(布)(平)(台)(,龙)(虎)(和)(仅)(提)(供)(信)(息)(存)(储)(空)(间)(服)(务)(。<br />阅)(读)(()<br />)!

作者:【龙虎和代理】


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