3.0T MR扩散张量成像在脑梗死诊断中的应用

目的：探讨3.0T磁共振扩散张量成像（DTI）对脑梗死的诊断价值。方法：对75例不同时期脑梗死患者进行MRI常规检查、扩散加权成像（DWI）及DTI检查,重建平均扩散系数（DCavg）图及部分各向异性（FA）图。以T2WI与DWI图像为参照,测定各期脑梗死灶及对侧正常脑组织的平均DCavg值、平均FA值,并进行统计学处理。结果：与对侧正常脑组织相比,脑梗死平均DCavg值在超急性期及急性期显著减低（P〈0.01）,随着时间延长呈逐渐恢复升高的变化趋势;脑梗死平均FA值在超急性期无一致性变化,与对侧正常脑组织相比差异无统计学意义（P〉0.05）,可轻度升高或轻度降低,随着病程进展呈不可恢复持续减低规律。结论：联合DCavg值与FA值可对脑梗死进行更精确的临床分期,有助于及时准确了解脑梗死的病理生理改变,为临床治疗及预后判断提供依据。     

磁共振弥散加权成像对急性脑梗塞的诊断价值

目的：评价磁共振弥散加权成像对急性脑梗塞的诊断价值及对急性和非急性脑梗塞的鉴别诊断价值。方法：对临床怀疑急性脑中风35例患者，进行常规T2WI和DWI检查，并采用盲法进行对照观察。对DWI图像上出现的异常高信号的病变部位进行准确定位，并判断病变部位与临床症状与体征是否相符，对DWI图像上出现的异常高信号与FSE序列T2WI像上的表现进行对照观察。结果：35例在DWI像上均出现异常信号，其中3例是在发病后6h内进行MRI检查，而在常规T2WI像上未显示异常信号；2例是在发病后12h内进行检查，而在常规T2WI像上仅表现稍高信号；10例患者在发病后12～24h内进行检查，20例患者在发病后24-72h进行检查，在T2WI和DWI像上均出现异常高信号；其中8例在FSE T2WI像上表现为多发脑梗塞病灶，而在DWI像上显示为单一异常高信号。在DWI像上诊断急性脑梗塞的敏感性及特异性均为100％。结论：DWI图像比常规T2WI图像对诊断急性脑梗塞有较高的敏感性及特异性，能发现常规T2WI像不能发现的超早期脑梗塞，并能鉴别急性和非急性脑梗塞，故DWI图像在诊断急性脑梗塞具有十分重要的诊断价值。     

Change of diffusion anisotropy in patients with acute cerebral infarction using statistical parametric analysis

Purpose We conducted statistical parametric comparison of fractional anisotropy (FA) images and quantified FA values to determine whether significant change occurs in the ischemic region. Materials and methods The subjects were 20 patients seen within 24 h after onset of ischemia. For statistical comparison of FA images, a sample FA image was coordinated by the Talairach template, and each FA map was normalized. Statistical comparison was conducted using SPM99. Regions of interest were set in the same region on apparent diffusion coefficient (ADC) and FA maps, the region being consistent with the hyperintense region on diffusion-weighted images (DWIs). The contralateral region was also measured to obtain asymmetry ratios of ADC and FA. Results Regions with areas of statistical significance on FA images were found only in the white matter of three patients, although the regions were smaller than hyperintense regions on DWIs. The mean ADC and FA ratios were 0.64 ± 0.16 and 0.93 ± 0.09, respectively, and the degree of FA change was less than that of the ADC change. Significant change in diffusion anisotropy was limited to the severely infarcted core of the white matter. Conclusion We believe statistical comparison of FA maps to be useful for detecting different regions of diffusion anisotropy. This article was presented at a Japan Radiological Society meeting in April 2005     

A comparison of images generated from diffusion-weighted and diffusion-tensor imaging data in hyper-acute stroke

PURPOSE: To compare isotropic (combined diffusion-weighted image [CMB], apparent diffusion coefficient [ADC], TRACE, exponential ADC [eADC], and isotropically-weighted diffusion image [isoDWI]) and anisotropic (relative anisotropy [RA], fractional anisotropy [FA], and volume ratio [VR]) diffusion images collected with fast magnetic resonance (MR) diffusion-weighted (DWI) and diffusion-tensor (DTI) acquisition strategies (each less than one minute) in hyper-acute stroke. MATERIALS AND METHODS: Twenty-one patients suffering from ischemic stroke-imaged within six hours of symptom onset using both DWI and DTI-were analyzed. Regions of interest were placed in the ischemic lesion and in normal contralateral tissue and the percent difference in image intensity was calculated for all nine generated images. RESULTS: The average absolute percent changes for the isotropic strategies were all > 38%, with isoDWI found to have a difference of 50.7% +/- 7.9% (mean +/- standard error, P < 0.001). The ADC maps had the most significant difference (-42.4% +/- 2.0%, P < 0.001, coefficient of variation = 0.22). No anisotropic images had significant differences. CONCLUSION: Anisotropic maps do not consistently show changes in the first six hours of ischemic stroke; therefore, isotropic maps, such as those obtained using DWI, are more appropriate for detecting hyper-acute stroke. Anisotropic images, however, may be useful to differentiate hyper-acute stroke from acute and sub-acute stroke.     

DWI、MRA在急性脑缺血中的联合诊断价值

目的探讨磁共振弥散加权成像（DWI）与磁共振血管成像（MRA）在急性期脑缺血中的联合诊断价值。方法收集经临床和影像学确诊为急性脑梗死的患者40例,所有患者行常规MRI、FLIAR、DWI及MRA检查。对MRA原始图像进行最大密度投影（MIP）重建,选取病灶中心和健侧相应部位8×8像素大小区域,测定各自的表观扩散系数（ADC）,并计算rADC值。结果 40例患者的DWI图像均显示与临床症状及体征相符的病灶,尤其是在超急性期,病灶具有较高的信号强度和清晰度。MRA检查均获得清晰血管图像,结果显示动脉硬化3例,动脉狭窄或闭塞28例;40例中,24例大面积病灶的血管病变阳性率为100%。DWI显示病灶解剖定位均与MRA上血管异常解剖定位有较好的一致性。结论 DWI对脑梗死超急性期、急性期均有很高的敏感性,MRA对颅内大血管及其部分分支的狭窄或闭塞情况均能很好地显示。通过DWI和MRA联合扫描进行比较,可以对应显示同一区域脑实质和脑血管情况,进一步判定责任血管。     

脑梗死在扩散加权像上信号强度及表面扩散系数变化的时间过程

目的 探讨脑梗死在扩散加权像（ｄｉｆｆｕｓｉｏｎ ｗｅｉｇｈｔｅｄ ｉｍａｇｉｎｇ,ＤＷＩ）上信号强度、表面扩散系数（ａｐｐａｒｅｎｔ ｄｉｆｆｕｓｉｏｎ ｃｏｅｆｆｉｃｉｅｎｔ,ＡＤＣ）变化的时间过程及两者的关系。方法 ５６例脑梗死病人计１０７个病灶接受ＭＲ ＤＷＩ检查,计算病变的信号强度比值（ｓｉｇｎａｌ ｉｎｔｅｎｓｉｔｙ ｒａｔｉｏ,ＳＲ）、ＡＤＣ及相对ＡＤＣ（ｒＡＤＣ）,根据ＤＷＩ和Ｔ２     

High-resolution isotropic 3D diffusion tensor imaging of the human brain.

High-resolution cardiac-gated 3D diffusion tensor imaging (3D-DTI) is demonstrated in vivo for several areas of the human brain. Anatomical mapping of subcortical white matter (WM), as well as definition and identification of major WM bundles from the brainstem were performed in humans for the first time using this technique. Improved intrinsic signal-to-noise ratio (SNR) and relatively reduced sensitivity to physiological motion (e.g., brain pulsations) with respect to cardiac-gated multislice acquisition are demonstrated. The advantages and weaknesses of this approach are discussed.     

急性脑梗死患者脑微出血的发生及相关危险因素研究

目的探讨急性脑梗死后发生脑微出血（CMB）的危险因素。方法回顾性分析2008年9月-2011年10月于我院神经内科就诊的脑梗死患者的一般资料、临床、实验室及影像学检查资料,对比脑微出血阳性组与阴性组患者的各项记录指标,并采用多元回归方法对脑微出血阳性组患者进行危险因素分析。结果两组患者年龄、高血压、服用抗血小板药物、腔隙性脑梗死、脑白质稀疏等方面具有显著差异（P〈0．05）,腔隙性脑梗死、脑自质稀疏、高血压、高血脂是急性脑梗死患者微出血发生的危险因素。结论脑微出血在急性脑梗死患者中有较高的发生率,其与腔隙性脑梗死、脑白质稀疏、高血压、高血脂密切相关。     

磁共振弥散加权成像在脑梗死诊断与评估中的应用研究

目的:研究磁共振弥散加权成像在脑梗死诊断与评估方面的作用。方法:本组共18例,均接受包括弥散加权成像(DWI)在内的颅脑磁共振检查。结果:脑梗死随着病变时间的增加,其表观弥散系数(ADC)发生一系列的变化,在急性期病变局部的ADC减低,在DWI中显示为高信号,在ADC图像上显示为低信号,稳定期病变局部的ADC逐渐恢复到正常水平附近,慢性期病变局部的ADC增加,在DWI呈低信号,在ADC图像上呈高信号。结论:磁共振弥散加权成像能比较准确、可靠地诊断早期脑梗死并反映脑梗死的病理生理基础。     

超急性脑梗塞的磁共振诊断

目的：探讨磁共振检查一常规扫描、快速液体衰减反转恢复(FLAIR)技术、弥散加权成像(DWI)及磁共振血管造影(MRA)在超急性脑梗塞诊断中的应用价值。方法：应用磁共振常规T1、T2WI、FLAIR序列、单次激发平面回波三向同性DWI和MRA对18例发病6h内的脑梗塞患者进行检查。结果：13例患者在常规MPI未发现病灶；其中5例FLAIR表现病灶区稍高信号；DWI成像均显示缺血灶，呈高信号，随b值增高病灶区信号强度逐渐上升，表现弥散系数(ADC)图病灶表现低信号。另有5例T2WI发现多发高信号灶，FLAIR呈低信号或低信号周边有高信号环，为陈旧性梗塞，DWI可同时显示T2WI未显示的新鲜梗塞灶及T2WI高信号的陈旧性梗塞灶，在ADC图上新鲜梗塞灶呈低信号，陈旧性梗塞呈等或高信号。MRA显示病灶区供血动脉阻塞、变细、局部狭窄或远端分支减少。结论：DWI及ADC图对超急性脑梗塞较常规MRI具有更高的敏感性和特异性，FIAIR序列亦较常规T2WI检出病变更敏感，MRA可直接显示阻塞血管的部位及程度，四者结合能快速、准确地诊断超急性脑梗塞，直接显示病变部位、范围、程度，为临床选择治疗方案提供较多信息。     

CT脑灌注与血管造影在急性脑梗死中的临床应用

目的:探讨64层螺旋CT脑灌注成像和脑血管造影技术在急性期脑梗死中的应用价值。方法:应用PhilipsBrilliance CT 64,对30例发病12h内急性脑缺血患者行CT平扫、CT脑灌注成像(CTP)和CT血管造影(CTA)检查。分析平扫及灌注成像表现,计算出缺血区脑血流参数,包括:脑血容量图(CBV)、血流量图(CBF)、对比剂平均通过时间(MTT)和对比剂峰值时间(TTP),与对侧相应区灌注参数进行比较,并重建颈段和脑内动脉CTA图像。所有病例在发病后3~14天复查CT平扫。结果:30例患者中16例头颅平扫发现早期脑梗死征象,14例常规平扫未发现异常,而CTP均发现灌注异常区。CTP表现为CBF及CBV减低、MTT及TTP延迟;患侧CBF、MTT、TTP与对侧差异有显著性意义(P<0.01),患侧CBV与对侧差异无显著性意义(P>0.01)。重建CTA图像显示16例一侧颈内动脉狭窄,8例一侧大脑中动脉狭窄(其中1例伴大脑后动脉狭窄、左侧后交通动脉闭塞);4例左侧大脑中动脉闭塞,2例左侧颈内动脉闭塞。结论:CTP能够早期、及时、准确地反映缺血部位及程度,预测半暗带;CTA可以显示病变血管的部位和程度;联合应用两者,对早期诊断急性脑缺血和指导治疗有重要价值。     

多高b值3.0T磁共振在急性脑梗死微小病灶检出中的应用

目的 探讨多b值磁共振成像在急性脑梗死中检出微小病灶的价值.方法 对临床诊断急性脑梗死的9例患者,进行多b值扩散加权磁共振检查(b值取0 s/mm2,1 000 s/mm2,1 500 s/mm2,2 000 s/mm2,3 000 s/mm2,4 000 s/mm2),按b值不同分为B1000组、B1500组、B2000组、B3000组及B4000组;对不同b值下显示的梗死病灶数进行统计学分析.结果 B2000组及B3000组病灶显示个数高于B1000组并且有统计学差异(P=0.007,0.038);B1500组及B4000组病灶显示个数与B1000组相比统计学无显著差异(P=0.081,0.062).结论 在急性脑梗死MRI检查中,b值取2 000 s/mm2及3 000 s/mm2时较b值取1 000 s/mm2时能发现更多微小病灶.     

头颈部CTA联合MR的DWI序列在诊断急性期脑梗死中的应用

目的：探讨螺旋CT脑血管成像（CTA）技术、MR的DWI序列的成像原理及其对急性期脑梗死的诊断价值。方法：对33例临床高度怀疑急性期脑梗死的患者,先行头颅MR检查,DWI上发现极高信号,然后行头颈部CTA检查,综合分析临床症状和影像学结果。结果：头颈部CTA可精确显示3级以上颅内动脉狭窄的部位、程度、附壁斑块,狭窄血管的供血区与DWI上的极高信号均一致。结论：在急性期脑梗死患者中,DWI的检测很敏感,且具有相对特异性;CTA为病变血管的定位、临床治疗方法的制定及预后初步判断提供了有效的依据。颅脑MR的DWI序列上出现极高信号,应立即进行CTA检查。     

3D diffusion tensor MRI with isotropic resolution using a steady‐state radial acquisition

Purpose

To obtain diffusion tensor images (DTI) over a large image volume rapidly with 3D isotropic spatial resolution, minimal spatial distortions, and reduced motion artifacts, a diffusion‐weighted steady‐state 3D projection (SS 3DPR) pulse sequence was developed.

Materials and Methods

A diffusion gradient was inserted in a SS 3DPR pulse sequence. The acquisition was synchronized to the cardiac cycle, linear phase errors were corrected along the readout direction, and each projection was weighted by measures of consistency with other data. A new iterative parallel imaging reconstruction method was also implemented for removing off‐resonance and undersampling artifacts simultaneously.

Results

The contrast and appearance of both the fractional anisotropy and eigenvector color maps were substantially improved after all correction techniques were applied. True 3D DTI datasets were obtained in vivo over the whole brain (240 mm field of view in all directions) with 1.87 mm isotropic spatial resolution, six diffusion encoding directions in under 19 minutes.

Conclusion

A true 3D DTI pulse sequence with high isotropic spatial resolution was developed for whole brain imaging in under 20 minutes. To minimize the effects of brain motion, a cardiac synchronized, multiecho, DW‐SSFP pulse sequence was implemented. Motion artifacts were further reduced by a combination of linear phase correction, corrupt projection detection and rejection, sampling density reweighting, and parallel imaging reconstruction. The combination of these methods greatly improved the quality of 3D DTI in the brain. J. Magn. Reson. Imaging 2009;29:1175–1184. © 2009 Wiley‐Liss, Inc.     

利用SWI探讨急性脑梗死合并脑微出血静脉溶栓风险

目的：探讨急性脑梗死合并脑微出血(CMBs)的相关危险因素及静脉溶栓治疗后出血转化风险。方法收集164急性脑梗死患者,入院时均行常规 MRI 及 SWI 扫描,根据 SWI 上有无 CMBs 分为 CMBs 阳性组和 CMBs 阴性组,记录所有患者的一般临床资料,探讨 CMBs 的相关危险因素。静脉溶栓治疗后的76例患者,其中 CMBs 阳性组35例,CMBs 阴性组41例,分别计数2组患者 CMBs 数目增多或出现出血转化的例数。结果年龄、高血压病、腔隙性梗死、脑白质疏松与 CMBs 相关性显著(P <0.05)。静脉溶栓后2组患者间出血转化率差异无统计学意义(P >0.05)。结论性别、年龄、高血压病、腔隙性脑梗死、脑白质疏松是CMBs 的危险因素。急性脑梗死合并 CMBs 患者静脉溶栓治疗不会增加出血转化危险。     

扩散加权b0图像对脑微出血的诊断价值

 目的 探讨扩散加权b0图像对脑微出血(cerebral microbleeds, CMBs)的诊断价值。方法 回顾性分析95例接受磁敏感成像(susceptibility-weighted imaging,SWI)、扩散加权成像的患者图像资料,与磁敏感加权成像对比,评价b0图像对CMBs的检出率和诊断结果的可靠性。结果 95例中,SWI对CMBs的病例检出率是32%,检出632个CMBs,b0图像对CMBs的病例检出率是29%,检出201个CMBs,增加的CMBs均匀分布在各部位。两位阅片者对SWI图像Kappa值为0.86,对b0图像的Kappa值为0.83;同一阅片者对SWI的Kappa值为0.85,b0图像Kappa值为0.84。结论 b0图像在没有增加额外扫描时间的情况下,可以检出大部分CMBs,诊断结果具有很好的可靠性、可重复性。     

Chronic hepatitis: role of diffusion-weighted imaging and diffusion tensor imaging for the diagnosis of liver fibrosis and inflammation

PURPOSE: To determine the diagnostic performance of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation. MATERIALS AND METHODS: Breathhold single-shot echo-planar imaging CDI and DTI with b-values of 0 and 500 second/mm(2) was performed in 31 patients with chronic liver disease and 13 normal volunteers. Liver biopsy was performed in all patients with liver disease with a median delay of two days from MRI. Fibrosis and inflammation were scored on a 5-point scale (0-4). Liver ADCs obtained with CDI and DTI were compared between patients stratified by fibrosis stage and inflammation grade. Receiver operating characteristic (ROC) curve analyses were conducted to evaluate the utility of the ADC measures for prediction of fibrosis and inflammation. RESULTS: Patients with liver fibrosis and inflammation had significantly lower liver ADC than subjects without fibrosis or inflammation with CDI and DTI. For prediction of fibrosis stage > or = 1 and stage > or = 2, area under the ROC curve (AUC) of 0.848 and 0.783, sensitivity of 88.5% to 73.7%, and specificity of 73.3% to 72.7% were obtained, for ADC < or =1.40 x 10(-3) mm(2)/second and < or =1.30 x 10(-3) mm(2)/second (using CDI), respectively. For prediction of inflammation grade > or = 1, AUC of 0.825, sensitivity of 75.0%, and specificity of 78.6% were obtained using ADC < or = 1.30 x 10(-3) mm(2)/second (using CDI). CDI performed better than DTI for diagnosis of fibrosis and inflammation. CONCLUSION: Liver ADC can be used to predict liver fibrosis and inflammation with acceptable sensitivity and specificity.     

苦碟子注射液联合依达拉奉治疗急性脑梗死的临床研究

目的：探讨苦碟子注射液联合依达拉奉治疗急性脑梗死的临床疗效。方法：选择我院2010-06-2013-06急性脑梗死患者140例,随机分为实验组和对照组,每组70例。两组患者均根据病情给予基本对症支持治疗,并严格控制血糖,血压等。在常规治疗基础上,实验组给予苦碟子注射液20ml加入5%葡萄糖注射液250ml,静脉滴注,1/d,同时给予依达拉奉31mg,注入0.9%氯化钠注射液90ml,静脉滴注,2/d;对照组给予依达拉奉31mg,注入0.9%氯化钠注射液90ml,静脉滴注,2/d。2周后观察两组患者血液学变化、临床疗效、神经损伤及不良反应。结果：2周后,实验组的临床疗效、神经损伤评分、血液学指标均优于对照组,差异有统计学意义（P〈0.05）,在治疗过程中均无不良反应发生。结论：苦碟子注射液联合脉络宁治疗急性脑梗死可以有效改善急性脑梗死患者的血液流变学,提高急性脑梗死患者的临床疗效,有一定的临床应用价值。     

Time course of the apparent diffusion coefficient after cerebral infarction

The purpose of this study was to evaluate quantitative apparent diffusion changes in the center of infarction by measurement of the apparent diffusion coefficient (ADC), and to investigate the influence of ischemia on the contralateral hemisphere. By diffusion echo-planar imaging (EPI) 52 patients showing cerebral infarction were studied within 5 h to >12 months after onset of clinical symptoms. Using three diffusion gradient strengths (b1=30 s/mm(2); b2=300 s/mm(2), b3=1100 s/mm(2)) ADC maps were generated. After onset of ischemia, ADC in the center of infarction was lower than in the contralateral regions of human brain. At first ADC declined for approximately 28 h to a minimum of approximately 150x10(-8) cm(2)/s. Then the ADC reincreased and reached a "pseudonormalization" after approximately 5 days. Chronic infarctions did show much higher ADC values (2000x10(-8) cm(2)/s) than unaffected areas. Neither localization nor size of infarctions showed a significant influence on this time course. In the center of infarction diffusion is isotropic. Even brain regions of the contralateral hemisphere are influenced by cerebral ischemia. In these regions ADC is higher than for physiological conditions. The ADC also declines especially for the first 2-3 days after onset of symptoms, also followed by reincrease. The ADC calculation enables determination of the onset of infarction more exactly than is possible using only diffusion-weighted imaging. Diffusion in the center of infarction is isotropic; hence, orientation of the diffusion gradients has no significant influence on sensitivity of measurements. The calculation of the ADC ratio based on data derived from the center of infarction and the contralateral hemisphere seems to be critical because the ADC in the unaffected contralateral hemisphere also changes.     

急性脑缺血表观扩散系数成像的实验研究

用改良的线栓法大脑中动脉阻塞模型,探讨急性脑缺血及再灌注的表现扩散系数成像特点。方法：２０只ＳＤ大白鼠,分为４组：Ａ组（８只）,非再通组,Ｂ、Ｃ、Ｄ组（各４只）,分别于ＭＣＡＯ３０ｍｉｎ、１ｈ、２ｈ后再通,于不同时间点作ＡＤＣ成像和Ｔ２ＷＩ,并测量感兴趣区的ＡＤＣ、相对ＡＤＣ（ｒＡＤＣ）。结果：ＭＣＡＯ后１５ｍｉｎ好出现缺血区ＡＤＣ下降,而Ｔ２ＷＩ最早在栓塞后２ｈ出现异常。６ｈ内缺血区,ＡＤＣ及ｒ