MichaelC.PawlakTeamLeaderLCB,BUMRClinicalApplicationsApril13-15,2010MeettheArtifactsKnowYourEnemyInternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20102Acknowledgements•Majorcontentcontributionsfrom:–“Artefacts”(v0702)AW4250•PMSAcademyInternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20103主要内容•伪影:是指在MR成像过程中出现的与解剖异常或生理异常无关的任何异常MR图像.——伪影类型——形成原因InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20104硬件相关伪影•源于系统问题：–硬件组件相关(梯度放大器之间或不同类型射频放大器等原因所致）–硬件组件性能(如随时间老化等)InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20105•双轮廓伪影硬件相关伪影SSh-DWI各向同性图像‘“双轮廓”或“像素偏移”伪影纠正涡流InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20106•模糊影/鬼影•如果仅仅出现在成像对象上，那么很可能是因为缺乏高级指令文件所造成的。•注意排除上述原因硬件相关伪影梯度放大器故障InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20107•与SENSE技术相关的模糊影/鬼影硬件相关伪影•噪声增加•云絮状背景•出现在SENSE技术扫描•所有线圈•4个坏的接收通道InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20108•扭曲、变形硬件相关伪影•源于磁场缺陷•磁场缺陷主要来自:–B0-场–梯度场–铁、磁性材料–非铁磁性材料,磁化率•这些缺陷会被叠加到频率编码梯度上并导致图像数据的错误编码•由于没有180°脉冲的再激励，所有梯度回波序列要比自旋回波序列对磁场缺陷更加敏感Non-lineargradientsDefectivegradientamplifierInternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,20109•图像不均•与射频线圈的灵敏度有关硬件相关伪影SHCCoilElementFailureSBCCoilElementFailureInternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201010硬件相关伪影有缺陷的线圈元件导致噪声突破不同于传统的SENSE噪声突破，这种噪声是由于位置和外观同线圈元件位置重叠InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201011•图像不均硬件相关伪影SPIR序列失败这个例子后被证实是匀场问题.这个图像出现太多线条.(每个黑白间隔代表一个PPM.，2PPM将导致压脂失败.)InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201012硬件相关伪影•图像不均–“SENSE序列扫描中出现黑斑”•运用Sense或Clear序列可见于所有线圈•定位扫描数据问题•更换QBC混合箱InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201013硬件相关伪影•射频干扰点状伪影•系统故障InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201014硬件相关伪影射频干扰•心脏研究•线状伪影,噪声•交换电池，无变化•更换导线，无变化•更换VCG模块,故障消除InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201015硬件相关伪影梯度电缆过滤器问题•InteraNova1.5T•R11.1.2.0•线影•所有线圈•一层•间歇出现射频干扰InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201016•带状伪影硬件相关伪影电脑主机更换后故障消失InternaluseonlyTeamLeaderLCB,BUMRClinicalApplications,MichaelC.Pawlak,April13-15,201017•FID伪影(激励回声）硬件相关伪影T1/PDTSE最明显解决方案:运用2“real”NSA’s(2个无折叠抑制,或4个折叠抑制)如果2realNSA’s不能够被用作激励梯度，通过设置Flowcomp=yes可减少这种现象出现InternaluseonlyTeamLe...
