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1、The application of SWI in cerebral tumor SWI在颅内肿瘤中的应用,Zhao Shanshan,Introduction,Susceptibility-weighted imaging (SWI) is a novel magnetic resonance (MR) technique that exploits the magnetic susceptibility differences of various tissues, such as blood, iron and calcification.磁敏感加权成像（SWI）是一种利用组织磁敏感性差
2、异产生图像的磁共振新技术，例如出血、铁和钙化,Introduction,SWI consists of using both magnitude and phase images from a high-resolution, three-dimensional fully velocity-compensated gradient echo sequence.SWI包括强度图和相位图，分辨率高且是三维高速补偿梯度回波 Magnitude images increase the conspicuity of the smaller veins and other sources of susc
3、eptibility effects,which is depicted using minimal intensity projection(minIP)应用最小强度投影(minIP)技术对强度图像进行后处理，可以使静脉及其它磁敏感物质显示更清楚,Introduction,Susceptibility-weighted imaging is better able to define the internal architecture of the lesion in comparison to conventional MR sequences as well as to CE T1-we
4、ighted images磁敏感加权成像较常规MR序列如CE-T1加权成像，更好的显示病灶内部结构 The internal architecture of tumors varies significantly between SWI and CE T1 imaging.SWI上和CET1图像显示肿瘤内的结构明显不同,Diversity,Internal architecture in CE T1: determined by the presence of necrosis, cysts, and tumor boundariesCE T1可显示的内部结构：坏死、囊变和肿瘤边缘 Inter
5、nal architecture in SWI : determined mostly by blood products either from venous vascular content and micro-hemorrhage in a tumorSWI可显示的内部结构：主要由其内部的血液成分决定，脉管系统和瘤内微出血,Figure 1. SWI (right) shows regions of venous vascular content and hemorrhage in a tumor,which are not seen in the conventional postco
6、ntrast T1-weighted image (left). 图1. SWI(右)能显示常规T1 增强图像(左)不能显示的瘤内微量出血和脉管系统,Fig. 2 Glioblastoma multiformae.a CE fat-suppressed axial T1-weighted images showing the necrotic heterogeneously enhancing mass in the right frontal lobe. b Axial 2D GRE. c minIP SWI. Note that the tumor neovascularity and h
7、emorrhages are better shown in SWI3.SWI illustrates the hemoglobin breakdown products within the tumor not detected in conventional images,图2. 多形性恶性胶质瘤. a. CE 压脂轴位T1加权图像，右侧额叶可见含坏死的不均匀强化肿瘤；b. 轴位2D GRE. c. minIP SWI. SWI 可显示常规序列不能显示的血红蛋白降解产物,Value,This difference in image appearance can allow recurren
8、t tumor to be distinguished from postsurgical trauma.由于显示的图像不同，可区分术后出血和复发肿瘤 While necrosis is also a factor that determines the internal architecture in SWI sequences and T1 sequences, late enhancement on T1 sequences shows homogenization of signal between necrotic andparenchymal tumor regions. 其中T1
9、和SWI上显示的瘤内坏死结构也是另一个影响因素，增强T1上肿瘤坏死和实质区域显示信号均匀 On CE SWI images, necrotic regions become high in signal compared to the low signal tumor parenchyma CE SWI上坏死区域显示高信号，而肿瘤实质区域显示低信号,Figure 3. Metastasis of lung adenocarcinoma in the left fronto-parietal area.CE T1 imaging (b), in comparison with precontra
10、st T1 imaging (a), shows two areas that did not enhance and likely correspond to necrosis. The same areas appear bright on T2 (not shown), supporting that hypothesis. CE SWI (d), in comparison with SWI (c), shows an enhancement of the same areas, suggesting late enhancement due a leakage of contrast
11、 agent because CE SWI was performed at least seven minutes after the CE T1 imaging. The dark margins of the tumor keep the same hypointense signal after contrast, suggesting venous vasculature,Figure 3.额顶叶肺腺癌转瘤。CE T1(b)与常规T1(a)对比，两个没有强化的区域是相应的坏死区域，在T2上信号显示更亮些(无图像)，能够证实这个假设。CE-SWI(d)与SWI(c)对比，同样的区域出现
12、强化；由于CE SWI是在CE T1图像后至少几分钟后采集，故延迟强化是因为造影剂泄露造成。增强后肿瘤低信号区仍显示低信号，考虑是静脉脉管系统,Value,Susceptibility-weighted imaging also provides FLAIR-like contrast because the CSF is suppressed while edema is enhanced relative to the normal tissue . This unique contrast combination of T2* effects and edema within a sin
13、gle image allows for improved detection of space-occupying lesions. 磁敏感加权图像可以显示液体反转序列显示的对比信号；因为与正常脑组织对比水肿信号被强化时，CSF信号被抑制。这种独特的对比结合单幅图像中T2*效应和水肿能够增加占位效应明显病灶的检出,Fig. 4 Primary central nervous system (CNS) lymphoma. a CE fat-suppressed axial T1-weighted images. Note the intensely enhanced splenial lesi
14、on. b Axial FLAIR. c minIP SWI, showing areas of hemorrhage and perilesiona edema well 图4. 原发性中枢神经淋巴瘤。a.轴位 CE-压脂T1加权图像。胼胝体压部病灶明显强化。b. 轴位FLAIR；c. minIP SWI，能很好显示出血和 病灶周围水肿区域,Value,Phase images of SWI are needed to differentiate tumor vasculature from calcifications since both show hypointensity on mi
15、nIP images. 由于脉管系统和钙化在minIP图上均显示低信号， SWI相位图可用于鉴别两者 Calcium, being diamagnetic, shows negative phase (in left-hand MR systems) and is thereby hypointense in phase images.钙化是逆磁性物质显示负相位(左手MR系统)，因此在相位图上显示低信号 Tumor vasculature due to the presence of increased deoxy-Hb shows a paramagnetic effect with a r
16、esultant positive phase on phase SWI images瘤血管内存在大量脱氧血红蛋白可产生顺磁性效应，在SWI相位上呈正相位,Fig. 5 Right frontal oligodendroglioma.a NECT. Note the calcified cortical based lesion (thick arrow). b Axial 2D GRE showing the calcification (thick arrow). c SWI minIP showing the calcification (thick arrow)and the peri
17、pheral vessel (thin arrow), both of which are hypointense. d CE fatsuppressed axial T1-weighted image showing the enhancing peripheral vein (thin arrow).e SWI phase showing the calcification (thick arrow) and the deoxy-Hb in the peripheral vein (thin arrow) showing opposite phase information;consequently, the two will be differentiated,
