磁共振成像伪影培训课件.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,磁共振成像伪影,*,*,First level,Second level,Third level,Fourth level,Fifth level,This text substitutes the headline.This is a substitution text.,*,磁共振成像伪影,*,*,First level,Second level,Third level,Fourth level,Fifth level,This text substitutes the headline.This is a substitution text.,*,磁共振成像伪影,*,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,磁共振成像伪影,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,磁共振成像伪影,磁共振成像伪影,First level,Second level,Third level,Fourth level,Fifth level,This text substitutes the headline.This is a substitution text.,*,*,*,First level,Second level,Third level,Fourth level,Fifth level,This text substitutes the headline.This is a substitution text.,*,磁共振成像伪影,磁共振成像伪影,First level,Second level,Third level,Fourth level,Fifth level,This text substitutes the headline.This is a substitution text.,*,磁共振成像伪影,Preface,伪影是图像中与相应断层组织的空间分布不相对应的信号强度,通常有生理和技术因素引起,2,磁共振成像伪影,边缘伪影：,幻影、化学位移、环状伪影,失真,包绕伪影,流动伪影,Category,3,磁共振成像伪影,Category,图像处理伪影,病人相关伪影,射频相关伪影,外磁场伪影,磁化率伪影,梯度相关伪影,数据错误,流动相关伪影,混叠、化学位移、截断、部分容积,运动伪影、魔角,层间交叉、拉链伪影、射频馈通、射频噪音,磁场不均匀,抗磁性、顺磁性、铁磁性，金属,涡流、非线性、几何变形,4,磁共振成像伪影,图像处理伪影,1,、混叠（,Aliasing,）,-,卷折（,Wrap-around,）,Aliasing,假名,原因采样不足,例：快速行驶的车轮倒转,时机,FOV,小于感兴趣区,特点出现在正常位置的对侧,5,磁共振成像伪影,6,磁共振成像伪影,复习：,MRI,的定位,7,磁共振成像伪影,在视野以外，仍然有磁场,在视野边缘，梯度没有停止,由此视野外结构将会产生一个超过视野内最大（小）频率的频率,计算机不能识别超大（小）频率，误认为带宽以内频率,较高频率误被识别为所选择带宽内较低频率,8,磁共振成像伪影,9,磁共振成像伪影,频率编码方向,10,磁共振成像伪影,相位编码方向,11,磁共振成像伪影,对 策,表面线圈：包绕整个身体,增加,FOV,过采样：频率过采样,相位过采样,饱和脉冲,3D,成像：层面选择方向出现，,放弃开始及最后几层即可,12,磁共振成像伪影,13,磁共振成像伪影,14,磁共振成像伪影,过采集后（频率方向）,15,磁共振成像伪影,多个方向伪影,16,磁共振成像伪影,17,磁共振成像伪影,频率方向过采集后,18,磁共振成像伪影,相位方向过采集后,19,磁共振成像伪影,频率、相位方向过采集后,20,磁共振成像伪影,图像处理伪影,2,、化学位移伪影（,Chemical shift,）,原因不同分子中的氢质子进,动频率略有不同,例：脂肪水（,3.5 ppm,）,1.5 T 220 Hz,场强越高越明显,位置眼眶、椎体终板、肾,特点信号位置相对、相反,T1WI,PD,FSE-T2WI,明显,SE-T2WI,不明显（？）,21,磁共振成像伪影,位置的判断采用水的共振特定,由于水、脂肪共振频率的差异,（水中氢质子高于脂肪中,H,）,二者共同导致脂肪位置错误，,在,1.5 T,彼此相差,2,个象素,较低频率处频率重叠信号,较高频率处频率分离信号,22,磁共振成像伪影,23,磁共振成像伪影,24,磁共振成像伪影,25,磁共振成像伪影,26,磁共振成像伪影,27,磁共振成像伪影,28,磁共振成像伪影,29,磁共振成像伪影,30,磁共振成像伪影,31,磁共振成像伪影,32,磁共振成像伪影,33,磁共振成像伪影,34,磁共振成像伪影,35,磁共振成像伪影,36,磁共振成像伪影,37,磁共振成像伪影,38,磁共振成像伪影,39,磁共振成像伪影,40,磁共振成像伪影,41,磁共振成像伪影,42,磁共振成像伪影,43,磁共振成像伪影,44,磁共振成像伪影,45,磁共振成像伪影,46,磁共振成像伪影,Syngo Multichannel spectroscopy,-excellent spectra,using 3D CSI for prostate,47,磁共振成像伪影,48,磁共振成像伪影,49,磁共振成像伪影,50,磁共振成像伪影,51,磁共振成像伪影,52,磁共振成像伪影,53,磁共振成像伪影,54,磁共振成像伪影,55,磁共振成像伪影,56,磁共振成像伪影,57,磁共振成像伪影,58,磁共振成像伪影,59,磁共振成像伪影,60,磁共振成像伪影,61,磁共振成像伪影,62,磁共振成像伪影,63,磁共振成像伪影,Without distortion correction,With distortion correction,64,磁共振成像伪影,66,磁共振成像伪影,67,磁共振成像伪影,68,磁共振成像伪影,69,磁共振成像伪影,Let images talk.,Argus results.,syngo,MagicView 300,70,磁共振成像伪影,Let images talk.,Argus results.,syngo,MagicView 300,71,磁共振成像伪影,Let images talk.,Argus results.,syngo,MagicView 300,72,磁共振成像伪影,Let images talk.,Argus results.,syngo,MagicView 300,73,磁共振成像伪影,Let images talk.,Argus results.,syngo,MagicView 300,74,磁共振成像伪影,Let images talk.,Argus results.,syngo,MagicView 300,75,磁共振成像伪影,Let images talk.,Spectroscopy results.,syngo,MagicView 300,76,磁共振成像伪影,Let images talk.,Spectroscopy results.,syngo,MagicView 300,77,磁共振成像伪影,Let images talk.,Spectroscopy results.,syngo,MagicView 300,78,磁共振成像伪影,Let images talk.,Spectroscopy results.,syngo,MagicView 300,79,磁共振成像伪影,