成人颅内原始神经外胚层肿瘤的MRI表现和病理对照

目的 探讨成人颅内原始神经外胚层肿瘤(primitive neuroectoderrnal tumors，PNET)的MRI特征，以期提高对该病的认识。方法回顾性分析了7例经手术和病理证实的成人颅内PNET的MRI表现，并与手术、病理相对照。结果 肿瘤多位于大脑半球和小脑蚓部，浸润性生长，瘤组织由低分化的小细胞构成，形态上可向多种细胞过渡。(2)MRI上肿瘤较大，4例呈浅分叶状，边界较清楚，瘤周水肿轻微；平扫呈不均匀较低T1、等或高T2信号，内部常伴有囊变和坏死区、可有出血和钙化；增强扫描6例肿瘤有明显的不均一强化；2例发生颅内转移，1例术后发生腰椎转移。结论 成人颅内PNET的MRI表现有一定特点；MRI有助于该病的诊断和指导治疗。     

1.5T场强下SE、GRE-EPI和弥散加权序列进行脑fMRI的对比研究

目的　探讨在 1.5T场强下自旋回波 (SE EPI) ,梯度回波 (GRE EPI)和弥散加权序列检测脑活动的能力。资料与方法　 5个右利手健康志愿者 ,在 1.5T场强下通过SE EPI、GRE EPI、弥散加权 (b值 =5 0s/mm2 )序列进行复杂对指运动事件相关性脑功能成像的对比研究 ,采用随机自带的fMRI后处理软件获取功能图像。同时对不同序列所获取的功能信号范围、大小面积和功能信号变化幅度进行t检验。结果　 5名志愿者在行复杂对指运动时 ,GRE EPI与SE EPI序列在显示神经元活动的分布范围相似 ,但在显示每个激活区面积 ,GRE EPI显示的明显大于SE EPI(t=- 8.195 ,P <0 .0 1)。GRE EPI和SE EPI序列均显示在刺激与静息间存在明显差异 (tgre=2 .788,Pgre<0 .0 1;tse=- 2 3.2 88,Pse<0 .0 1) ,且两种序列显示的功能信号变化幅度有显著差异 (t=- 9.2 85 ,P <0 .0 1)。而弥散加权序列未能检测出脑功能活动信号。结论　在 1.5T场强下现有的SE或GRE EPI序列均可获取脑功能活动信号 ,GRE EPI序列比SE EPI反映活动神经元敏感性高 ,主要是采集到引流大静脉的信号     

Diffusion-weighted Single-shot Echo Planar MR Imaging of Normal Human Prostate Using Different b Values

This study examined the effect of different b values on diffusion-weighted MR imaging （DWI） of human prostate by using single-shot spin echo echo planar imaging （SE-EPI） sequences, observed the normal appearances and measured apparent diffusion coefficient （ADC） values in anatomical regions of normal prostate. Twenty-four healthy volunteers （mean age： 32 y） were studied by using a 1.5T system with a phased array surface multicoil. Two kinds of single-shot SE-EPI sequence were used to perform DWI in the prostate in volunteers, with five b values being 0, 30, 300, 500 to 1000 s/mm2. The image quality with different imaging parameters was analyzed and the ADC values in anatomical regions of normal prostate were measured. DWI of prostate was successfully obtained in all volunteers. The images were of good quality, without artifacts containing pixels within the prostate. The contrast was good between the different anatomical regions of the prostatic gland, i.e., the peripheral zone （PZ）, which exhibited higher signal intensity, and the central gland （CG）. Signal intensity contrast was related to the magnitude of b values. The ADC values in PZ and CG were （1.27±0.22）×10-3 mm2/s and （1.01±0.17）×10-3 mm2/s,respectively. The ADC values were found to be significantly higher in PZ than in CG （P〈0.05, paired t-test）. Significant differences were found between the slice-selecting component and both the read-out and phase-encoding components of the ADC values. It is concluded that SE-EPI is a suitable DWI sequence for human prostate. The contrast between PZ and CG is good when b values are low, while the diffusion and ADC values are accurate when b values are high. ADC values are higher in PZ than in CG in normal prostate. Diffusional anisotropy is present in normal prostatic tissue.     

医学仿真内镜的原理、成像技术与临床应用

近年来 ,随着计算机技术的不断进步 ,医学影像学获得了长足的发展 ,其功能越来越多 ,应用领域越来越广。仿真内镜成像 (ｖｉｒｔｕａｌｅｎｄｏｓｃｏｐｙ ,ＶＥ)就是其中之一。ＶＥ所依赖的虚拟现实 (ｖｉｒｔｕａｌｒｅａｌｉｔｙ)技术最初是用于游戏软件中 ,用来模拟三维立体环境 ,以增加真实感的。后有人将其用于医学影像学 ,创造出了ＶＥ这一崭新的ＣＴ和ＭＲＩ图像后处理技术 ,它是能重建出管道器官如胃肠道、呼吸道、大血管等内表面的三维立体图像的一种虚拟内镜方法 ,因其类似纤维内镜 (ｆｉｂｅｒｏｐｔｉｃｅｎｄｏｓｃｏｐｙ ,Ｆ…     

外伤性视网膜脱离视网膜色素上皮细胞钙粘素表达变化

目的探究外伤性玻璃体积血视网膜脱离模型视网膜色素上皮细胞（RPE）细胞膜表面钙粘素（Cadherin）表达变化规律。方法90只健康有色兔，分为5组：Ⅰ组，外伤性玻璃体积血伴视网膜脱离组；Ⅱ组，孔源性视网膜脱离组；Ⅲ组，单纯视网膜裂孔组；Ⅳ组，玻璃体切除组；Ⅴ组，空白对照组。分别于手术后1、3、5、7、14、21、30d摘取眼球，酶消化和机械分离法分离RPE细胞，制成细胞悬液，用流式细胞仪检测RPE细胞膜上钙粘素表达水平。方差分析比较各组差异。结果各模型组RPE细胞钙粘素表达差异具有统计学意义（F=9．612；P〈0．001），Ⅰ组和Ⅱ组中RPE细胞钙粘素的表达水平明显低于Ⅲ组、Ⅳ组和Ⅴ组。不同时间点组中钙粘素表达差异具有统计学意义（F=7．95，P〈0．001）。Ⅰ组和Ⅱ组模型RPE细胞钙粘素表达均数无明显差异，与Ⅲ组、Ⅳ组和Ⅴ组比较差异显著。结论外伤性玻璃体积血伴视网膜脱离和孔源性视网膜脱离模型RPE细胞钙粘素表达在发病早期表达减弱，随着病情的发展钙粘素表达逐步恢复至正常。     

三维K-空间Kz轴数据不对称填充技术在3D-TOF脑动脉MRA的应用价值

目的探讨3D K-空间Kz轴数据不对称填充方法在3D TOF脑动脉MRA的应用价值.方法 40例患者行Kz轴K-空间数据不对称填充的3D TOF脑动脉MRA(Turbo MRA)及Kz轴K-空间数据对称填充的3D TOF脑动脉MRA(常规MRA),在3D源图像和MIP图像上比较二种方法的影像质量、成像时间及显示血管的能力.结果 Kz轴不对称K-空间填充3D TOF脑动脉MRA与Kz轴对称K-空间填充3D TOF脑动脉MRA相比,影像质量指标(S/N、C/N、Rz)、采集时间TA、血管显示能力等均有显著性差异(P<0.01).结论 Kz轴K-空间不对称填充3D TOF脑动脉MRA与常规3D TOF脑动脉MRA相比成像质量更佳,显示血管更多,节约采集时间44%.     

细胞因子对视网膜色素上皮细胞Cadherin表达的影响

目的探讨细胞因子对视网膜色素上皮（RPE）细胞钙黏附素（Cadherin）表达的影响及可能的调节机制。方法取体外培养的第2代兔眼RPE细胞，加入不同浓度的碱性成纤维细胞生长因子（bFGF）、肿瘤坏死凶子“（TNFα）、血小板源生长因子（PDGF）、肝细胞生长因子（HGF）共同培养12h后，用流式细胞技术定性、定量观察这4种细胞因子对RPE细胞膜上Cadherin表达的影响。结果正常兔RPE细胞可表达Cadherin，经各种细胞因子诱导后的RPE细胞Cadherin表达均明显下调，尤以4种细胞因子联合作用时表达下调最明显，其表达水平与细胞因子浓度呈剂量递减关系。不同浓度各组细胞因子与空白对照组比较，Cadherin表达具有显著统计学差异（P〈0．05）。同浓度不同细胞因子组间Cadherin表达具有显著统计学差异（P〈0．05）。结论正常兔RPE细胞可表达Cadherin，细胞因子bFGF、TNFα，PDGF、HGF能诱导RPE细胞Cadherin表达减弱，减弱的程度与剂量有关。     

MR心脏大血管成像三维稳态自由进动序列应用初探

三维稳态自由进动序列(three dimensional-steady state free precession,3D-SSFP)MRI是对心脏大血管的自由呼吸、导航门控、心电触发、各向同性的三维容积扫描,使得MRI对心脏大血管的显影在传统无创、无射线的基础上进一步实现了无需屏气及无对比剂显影,可综合评估心脏、大血管及冠状动脉异常.笔者对2008年8月至2010年2月临床怀疑有心脏大血管异常的患者进行了胸腔3D-SSFP扫描及传统心血管MR扫描(CMR),对比分析两种扫描方式的图像质量及诊断结果,并使用Bland-Altman法对两种扫描方式的心腔测量值进行一致性分析,探讨3 D-SSFP扫描对心脏大血管的评估价值.     

单激发厚层投射MR胰胆管成像及其应用价值

目的：探讨单激发厚层投射磁共振胰胆管成像（ＭＲＣＰ）显示胰胆管树的能力和对胰胆管梗阻性病变的诊断价值,材料与方法：用重Ｔ２加权单激发ＴＳＥ序列、厚层投身成像技术做ＭＲＣＰ检查共１５０例,正常组５０例,病变组１００例。分析其对正常胰胆管各主要结构的显示率及对梗阻病变的检出率、定位和定性诊断准确率,将结果与ＣＴ、ＵＳ、ＥＲＣＰ／ＰＴＣ及手术和病理相对照。结果：本法可显示管径１￣２ｍｍ的胰胆管分支;准确     

MRI Features of Intracranial Primitive Neuroectodermal Tumors in Adults： Comparing with Histopathological Findings

The MRI appearances of 7 adult patients with pathologically proven intracranial primitive neuroectodermal tumors (PNET) were retrospectively analyzed. The MRI features were compared with findings in pathology and surgery. In this group, the tumor masses were most commonly found in the semisphere of cerebrum and in the vermis of cerebellum. They were relatively large and 4 were in lobulated shape. All of them had well-defined margins. MR images showed the tumors to be mildly or obviously hypointense on T1-weighted images and hyperintense on T2-weighted images. Most masses had heterogeneous appearances with some cystic and necrotic areas. Intratumoral haemorrhage and focal calcification were occasionally seen. Mostly, there was no or only mild surrounding edema. Marked inhomogeneous contrast enhancement on MRI was seen in 6 cases except one. Two patients with multiple intracranial metastases were revealed on MR images. In this series, there was good correlation between MRI features and findings in pathology and surgery.These results showed that certain MRI features might suggest the diagnosis of intracranial PNET in adults. MRI is an effective technique to detect these tumors and is helpful to treatment planning and follow-up.