缺血性脑卒中超急性期MRI表现与病理动物实验研究

目的：应用０．５ＴＭＲ仪,实验研究缺血脑卒中超急性期ＭＲＩ表现扩期病理学基础。为临床治提供客观依据。材料与方法：实验组１６只家兔,采用改良Ｏ‘Ｂｒｉｅｎ法闭塞一侧ＭＣＡ制作动物模型。手术对照组４只。应用０．５ＴＭＲ仪行轴位Ｔ１ＷＩ／ＳＥ,Ｔ２ＷＩ／ＴＳＥ扫描。兔脑切片ＨＥ染色史镜下观察缺血区神经元形态改变。结果：ＭＣＡ＝Ｏ后最早出现缺血区Ｔ２ＷＩ／ＴＳＥ高信号表现为２小时３０分钟。３￣４小时６４．     

硬膜窦血栓形成的MRI表现(附6例分析)

目的：探讨硬膜窦血栓形成的ＭＲＩ表现。方法：６例硬膜窦血栓形成，均做了ＭＲＩ检查，其中２例用了ＳＴＩＲ，１例用了ＦＬＡＩＲ序列，３例作了增强检查（Ｇｄ－ＤＴＰＡ），５例作了ＭＲＶ。结果：右横窦栓塞２例，左横窦１例，上矢状窦３例，脑肿胀５例，静脉性脑栓塞２例，脑血肿１例。增强检查，脑皮质及皮质静脉增强１例。结论：ＭＲＩ对硬膜窦血栓形成的诊断有独特的价值。硬膜窦流空信号消失和硬膜窦狭窄、闭塞是直接征像。脑肿胀、静脉性脑梗塞、脑血肿是间接征像     

犬颈内动脉内冷灌注脑选择性降温对脑保护的实验研究

目的观察颈内动脉内冷灌注犬脑选择性降温对缺血性脑组织的保护作用。方法夹闭左侧颈总动脉、双侧椎动脉、左侧颈外静脉后,自右侧颈内动脉灌入低温灌注液以选择性降低脑温。将颅脑回流的低温稀释静脉血超滤并复温至３８℃后再输入体循环。结果１８只犬中有１４只完成了脑的选择性降温：（５．０±２．０）分钟内降至２８℃,（１０．３±７．２）分钟内降至２０℃,并维持在（１９±１．０）℃达５０分钟,直肠温度保持在（３２．５±２．０）℃以上。１０只长期存活,分别于术后１,２,８,１２周处死,病理检查示犬脑无神经细胞缺血性损伤改变。另４只实验初期因降温后血压显著下降而死亡。结论颈动脉内冷灌注液灌注,可选择性快速、安全地降低脑温,防止脑组织的缺血性损伤,为开展无血手术提供了实验依据。     

原发性脑静脉（窦）血栓形成的CT和MRI诊断

分析了７例原发性脑静脉窦血栓形成的ＣＴ和ＭＲＩ的征象。经静脉期脑血管造影和手术病理证实分别为５和１例，重复ＭＲＩ确诊１例，５例血栓在上矢状窦，１例在右侧横窦，１例位于左侧大脑中静脉。ＣＴ扫描２例显示脑静脉（窦）血栓直接征象。２例为非特征性改变，３例无阳性发现，２例行ＭＲＩ检查，受累静脉窦内Ｔ１、Ｔ２加权像上均为高信号，１例治疗后复查高信号消失，５例造影明确了静脉窦闭塞的部位和程度，２例可见静脉窦闭     

颅内黑色素瘤的影像诊断(附7例分析)

目的：探讨颅内黑色素瘤ＣＴ、ＭＲ影像特征及其诊断。材料和方法：７例颅内黑色素瘤患者中男４例,女３例,年龄１０～５９岁。５例皮肤有黑色素瘤,２例有颅内黑色素瘤切除史。２例行ＣＴ加ＭＲＩ,４例单行ＭＲ,１例仅行ＣＴ检查。结果：３例ＣＴ平扫均为高密度影,形态不规则。增强扫描肿瘤明显增强。６例ＭＲＩＴ１ＷＩ肿瘤均表现为高信号,其中５例Ｔ２ＷＩ低信号,１例低高信号。Ｔ１ＷＩ增强扫描６例不规则增强。结论：颅内黑色素性黑色素瘤ＭＲＩ具有特征性表现,而非黑色素性黑色素瘤不具特征性,ＭＲＩ显示黑色素瘤累及脑实质及浸润脑膜的范围和定性诊断优于ＣＴ。     

MEBO治疗口腔、消化道化学烧伤8例临床观察

本文介绍了利用ＭＥＢＯ治疗口腔，消化道烧伤８例，其中单纯口腔烧伤６例，口腔烧伤并伴食道胃粘膜煤伤２例，酸性剂烧伤５例，碱性剂烧伤２例，强氧化剂烧伤１例，伤后就诊时间多在２小时之内（６例）４小时１例，４天后１例。在局部治疗方面主要采用口服吸湿润烧伤膏（ＭＥＢＯ），口腔烧伤每次服５克，每２小时１次，食道胃烧伤患者服用药量为每次２０克，每２小时１次，口腔化学烧伤早期，先用大量清水漱口，一般持续为１０分钟     

脑静脉血管瘤的MRI及MRA

目的：探讨颅内静脉血管瘤的ＭＲＩ和ＭＲＡ影像学表现及诊断和鉴别诊断。材料和方法：应用ＳｉｅｍｅｎｓＭｅｇｎｅｔｉｏｎＶｉｓｉｏｎ１．５Ｔ超导系统对诊断静脉血管瘤（ＶＡ）２０例进行分析。ＭＲＩ扫描用ＳＥＴ１和ＴｕｒｂｏＳＥＴ２加权序列。ＭＲＡ采用ｔｏｆ－ｔｉ３Ｄ－ｍｕｌｔｉ－ｓｌａｂ－ｔｒａ－ｔｕｎ序列。１６例作增强Ｔ１加权及ＭＲＡ检查。血管重建采用ＭＩＰ技术。有１１例曾行ＣＴ检查，１例行手术治疗。结果：所有病例均由ＭＲ检查作出首诊。Ｔ１加权１８例显示扩张引流静脉呈点条状低信号影，有２例未显示，经增强后显示，并有部分髓静脉显示。Ｔ２加权引流静脉多呈高信号，个别呈低信号。较大的ＶＡ亦可显示髓质静脉。ＭＲＡ１５例显示异常血管，典型的表现为脑实质内见为数不等的髓质静脉呈伞状汇入一根异常扩张的引流静脉，整个形态似“水母头”。１例ＭＲＡ未显示病灶。结论：ＭＲ是诊断ＶＡ最好的影像方法，ＭＲＡ有助于确诊本病。增强ＭＲＩ及ＭＲＡ可提高ＶＡ的检出率     

脑实质型脑囊虫病的MRI诊断

目的：探讨脑实质型脑囊虫病各期的ＭＲＩ表现。材料和方法：５４例经临床和ＭＲＩ诊断的脑实质型脑囊虫病患者。其中３０例做了增强扫描。分析其在各个病理阶段的ＭＲＩ表现。结果：活虫期４０例，变性水肿期４５例，肉芽肿期５例，钙化期４例。活虫期ＭＲＩ发现圆囊腔内带有偏心的头节，是ＭＲＩ诊断脑囊虫病的确切依据。结论：ＭＲＩ能清楚显示脑囊虫病在脑内病变的大小、范围、数目和部位。ＭＲＩ的准确分期为临床治疗提供有力的帮助。     

Gd-DTPA增强MR扫描对脑发育性静脉异常的诊断价值

目的 对比分析ＭＲＩ平扫、增强扫描及ＭＲＡ对脑发育性静脉异常（ｄｅｖｅｌｏｐｍｅｎｔａｌ ｖｅｎｏｕｓ ａｎｏｍａｌｙ,ＤＶＡ）的显示价值,以期提高ＭＲＩ对脑ＤＶＡ的检出率及诊断正确率。材料与方法 回顾分析１２例脑ＤＶＡ的ＭＲＩ平扫、增强扫描及其中４例的ＭＲＡ表现,分别评价其对ＤＶＡ的引流静脉、髓静脉的显示价值。结果 １２例１４个ＤＶＡ。ＭＲ平扫８个ＤＶＡ可见引流静脉显影,５个ＤＶＡ扩张髓静脉区有     

低场强MR成像在胃癌诊断中的应用研究

目的：探讨低场强ＭＲ成像技术在胃癌诊断中的作用。材料与方法：５０例正常成人服用不同量的水和造影剂（Ｇｄ－ＤＴＰＡ）溶液、空气,注射或不注射低张药物后,进行多方位、多系列ＭＲ增强前后扫描以资对照。３０例进展期胃癌患者,空腹４￣８小时,检查前１０分钟肌注６５４－２ ２０ｍｇ,检查前即刻喝水６００￣１０００ｍｌ,行多方位、多系列增强前后扫描。１８例手术患者,术前进行ＴＮＭ分期和可切除性评估。结果：ＭＲＩ     

Opening of the blood-brain barrier by intravenous contrast media in euvolemic and dehydrated rabbits

It has been suggested that intravenous injections of hypertonic contrast media when used in computed tomography and digital subtraction angiography might raise plasma osmolality sufficiently to open the blood-brain barrier (BBB). The current investigation establishes the threshold of plasma osmolality that causes the the opening of the BBB in euvolemic and dehydrated rabbits. Euvolemic rabbits were allowed food and water ad libitum. Dehydrated rabbits received 4.0 mg/kg of furosemide intramuscularly and were deprived of water for 72 hours. Meglumine/sodium diatrizoate 76 per cent (n = 28) or mannitol 20 per cent (n = 12) was administrated intravenously, at a rate of 25 mmol/kg body weight/hour for 2, 3 or 4 hours. Plasma osmolality, blood iodine concentration, blood pressure, heart rate and hematocrit were assessed at regular intervals. Evans blue and 99Tcm-DTPA were used simultaneously as tracers for BBB opening. Rating of BBB opening with 99Tcm-DTPA correlated well with Evans blue staining (r = 0.863, p less than 0.001; n = 42). BBB opening was related to plasma osmolality and was similar for both contrast media and mannitol. Widespread BBB opening occurred above 400 mmol/kg while focal BBB opening occurred above 370 mmol/kg. Dehydration per se increased plasma osmolality but did not reduce the threshold for BBB opening.     

实验性部分兔脑组织切除术后早期影像学与病理学对照研究

目的　探讨正常脑组织部分切除术后早期的MRI特点和病理学基础。方法　选取 36只健康新西兰大白兔 ,按术后 1～ 10d的不同时间将动物分成 10个组 ,3、5、7、10d组各 6只动物 ,其余各组为 2只动物。 3%戊巴比妥耳缘静脉注射麻醉 ,无菌状态下切除右顶枕部分脑组织分别在术后1～ 10d行平扫及增强MR检查 ,随后立即取材 ,电子显微镜及普通光学显微镜下观察组织病理改变。结果　 (1)术后 2 4h术区边缘出现正常脑组织的反应性增强 ;(2 )术后一直到第 5天反应性强化程度逐渐加重 ,5d之后变化不明显 ;(3)术后 3d之内反应性增强为血脑屏障的破坏所致 ,3d之后为新生小血管和破坏的血脑屏障共同起作用 ,主要机制是新生血管数量的增加。结论　正常脑组织在术后早期反应性强化特点表现出明显的时间过程 ,在不同时间 ,血脑屏障的破坏和新生血管的数量对反应性增强所起的作用是不同的。     

A physiological barrier distal to the anatomic blood-brain barrier in a model of transvascular delivery

BACKGROUND AND PURPOSE: Osmotic disruption of the blood-brain barrier (BBB) provides a method for transvascular delivery of therapeutic agents to the brain. The apparent global delivery of viral-sized iron oxide particles to the rat brain after BBB opening as seen on MR images was compared with the cellular and subcellular location and distribution of the particles. METHODS: Two dextran-coated superparamagnetic monocrystalline iron oxide nanoparticle contrast agents, MION and Feridex, were administered intraarterially in rats at 10 mg Fe/kg immediately after osmotic opening of the BBB with hyperosmolar mannitol. After 2 to 24 hours, iron distribution in the brain was evaluated first with MR imaging then by histochemical analysis and electron microscopy to assess perivascular and intracellular distribution. RESULTS: After BBB opening, MR images showed enhancement throughout the disrupted hemisphere for both Feridex and MION. Feridex histochemical staining was found in capillaries of the disrupted hemisphere. Electron microscopy showed that the Feridex particles passed the capillary endothelial cells but did not cross beyond the basement membrane. In contrast, after MION delivery, iron histochemistry was detected within cell bodies in the disrupted hemisphere, and the electron-dense MION core was detected intracellularly and extracellularly in the neuropil. CONCLUSION: MR images showing homogeneous delivery to the brain at the macroscopic level did not indicate delivery at the microscopic level. These data support the presence of a physiological barrier at the basal lamina, analogous to the podocyte in the kidney, distal to the anatomic (tight junction) BBB, which may limit the distribution of some proteins and viral particles after transvascular delivery to the brain.     

亚低温对颅脑损伤后脑血管内皮细胞紧密连接开放的影响

目的　观察颅脑损伤后早期亚低温治疗对脑毛细血管内皮细胞紧密连接开放的影响 ,阐明亚低温降低伤后血脑屏障通透性的可能机制。　方法　Wistar大鼠 90只 ,随机分为常温对照组 (10只 )、常温损伤组 (40只 )和亚低温治疗组 (40只 )。在镧示踪法电镜下分别观察亚低温及常温条件下颅脑损伤后内皮细胞紧密连接的开放及其程度 ;用干 -湿重法测定常温损伤组及亚低温治疗组伤后不同时相脑组织含水量并行统计学分析。　结果　常温损伤组伤后 3h紧密连接初步开放 ,2 4～ 4 8h紧密连接开放达高峰 ,72h紧密连接仍大量开放。亚低温治疗组紧密连接仅轻度开放 ;亚低温治疗组脑组织含水量较常温损伤组明显减少 ,伤后 3,2 4 ,72h差异有显著性意义(P <0 .0 5 ) ,伤后 4 8h差异有非常显著性意义 (P <0 .0 1)。　结论　亚低温有减轻颅脑损伤后血脑屏障毛细血管内皮细胞紧密连接的开放程度及减轻脑水肿的作用 ,亚低温减轻伤后内皮细胞紧密连接开放是降低伤后血脑屏障通透性机制之一。     

Pulse sequence and timing of contrast‐enhanced MRI for assessing blood–brain barrier disruption after transcranial focused ultrasound in the presence of hemorrhage

Purpose:

To optimize the timing of contrast‐enhanced magnetic resonance imaging (MRI) that best indicates blood–brain barrier (BBB) disruption induced by focused ultrasound (FUS) along with an ultrasound contrast agent (UCA) and to verify that the contrast‐enhanced spin‐echo MRI sequence can indicate the degree and location of BBB disruption in the presence of hemorrhage better than a gradient‐echo sequence.

Materials and Methods:

Sonication was applied to 12 rat brains with four different doses of UCA to cause variable degrees of hemorrhage. Two imaging sequences were performed to acquire T1‐weighted (T1W) images at two time‐points after the administration of a T1‐shortening contrast agent. The contrast enhancement at the sonicated regions was quantified and correlated against Evans blue (EB) staining.

Results:

The spin‐echo T1W images at 10 minutes post–contrast enhancement showed the best correlation with EB staining in both quantity of EB extravasation (r = 0.812; P < 0.01) and spatial distribution (r = 0.528, P < 0.01). This capability was more robust than the gradient‐echo sequence.

Conclusion:

Our results suggest that contrast‐enhanced T1W spin‐echo sequence acquired in the early phase post–contrast enhancement should be considered to monitor the degree and location of BBB disruption under the possibility of hemorrhage induced by FUS. J. Magn. Reson. Imaging 2010;31:1323–1330. © 2010 Wiley‐Liss, Inc.     

血源性脑及脑膜转移瘤动物模型的建立及其MRI研究

目的 介绍建立血源性脑及脑膜转移瘤动物模型的方法,成瘤率的影响因素,讨论对脑膜及脑内转移瘤的检出效果及其表现基础。方法 ３８只新西兰大白兔随机分为３组,分别从颈总动脉行血脑屏障开放接种ＶＸ２癌细胞,单纯接种ＶＸ２癌细胞及单纯注射生理盐水。术后１周开始在不同时间行ＭＲＩ检查。病理取材ＨＥ及免疫组织化学染色光镜下观察。     

Association between contrast‐enhanced MR images and blood–brain barrier disruption following transcranial focused ultrasound

Purpose:

To investigate the correlation between the contrast‐enhanced magnetic resonance imaging (MRI) signal and the duration of blood–brain barrier (BBB) disruption induced by focused ultrasound (FUS).

Materials and Methods:

FUS was applied to 45 rat brains in the presence of microbubbles, and these rats were scanned on a 3T MRI system at several timepoints. The rat brains were then studied using contrast‐enhanced spin echo T1‐weighted images. At the same time, BBB disruption was evaluated based on Evans blue (EB) extravasation. The relationship between the normalized signal intensity change of the MRI and EB extravasation was analyzed by least‐squares linear regression and the calculation of correlation coefficients.

Results:

When MRI enhancement was quantitatively evaluated by EB extravasation, a strong correlation between the normalized signal intensity change of the MRI and EB extravasation was identified during BBB disruption after sonication. However, the correlation coefficient decreased as BBB closure occurred after sonication ended.

Conclusion:

The contrast‐enhanced MRI signal can potentially be used to evaluate the amount of chemotherapeutic agents entering the targeted tissue, but the accuracy of the assessment will be affected by the time interval since sonication. J. Magn. Reson. Imaging 2010;32:593–599. © 2010 Wiley‐Liss, Inc.     

Role of red blood cell deformation in toxicity of contrast media in cerebral angiography

The authors investigated the effect on the brain of red blood cells that had been modified by contrast media. Rat blood was mixed with an equivolume of contrast media, and up to 200 microL of the mixture was infused to the internal carotid artery of the rat. Evans blue was administered intravenously to assess the integrity of the blood-brain barrier (BBB). Immediately after the death of the animal, or 2.5 hours after the infusion, the brain was removed for evaluation of the degree of BBB destruction and edema. Extensive destruction of the BBB, cerebral edema, and death of the animals were induced by infusion of blood mixed with an ionic contrast medium, such as diatrizoate and iothalamate, which deformed red blood cells. Microscopic observation showed atrophy and necrosis of nerve cells and decomposition of nerve fibers in the affected area of the brain. Cerebral damage was not observed in rats injected with blood mixed with a nonionic contrast medium such as iopamidol, iopromide, or metrizamide, which had less effect on red blood cells. Cerebral damage also was observed in the rats injected with blood mixed with a hyperosmotic solution of mannitol, as well as washed red blood cells mixed with an ionic contrast medium. This study's results indicate that hyperosmotic ionic contrast media affect red blood cells and cause disturbance in cerebral circulation.     

Magnetic resonance imaging enhanced by superparamagnetic iron oxide particles: Usefulness for distinguishing between focused ultrasound‐induced blood–brain barrier disruption and brain hemorrhage

Purpose

To investigate the usefulness of a fully flow‐compensated heavy T2*‐weighted imaging enhanced by superparamagnetic iron oxide (SPIO) particles for distinguishing between focused ultrasound‐induced disruption of blood–brain barrier (BBB) and brain hemorrhage.

Materials and Methods

Focused ultrasound (frequency: 1.5 MHz) was used to induce disruption of the BBB in 39 rats. Two T2*‐weighted images were obtained before and after SPIO administration. Preenhanced T2*‐weighted images were used to detect hemorrhage. Detection of BBB disruption was performed on SPIO‐enhanced images. Thirty‐four rats were sacrificed after magnetic resonance (MR) scanning for histological confirmation of brain lesions. Theremaining five animals were followed up for 35 days. Prussian blue staining was performed on histological sections to detect SPIO particles in the brain.

Results

After SPIO injection the areas of BBB disruption in rat brain were significantly enlarged. The area of mismatch between the T2*‐weighted images indicated a safe region where BBB opening occurred without hemorrhagic complications. In the longitudinal study, removal of SPIO occurred at a faster rate in hemorrhagic areas, albeit being closer to that occurring in the liver. The presence of SPIO was confirmed by Prussian blue staining in brain parenchyma and capillary endothelial cells in areas of BBB disruption.

Conclusion

T2*‐weighted images—either with and without SPIO enhancement—may differentiate focused ultrasound‐induced BBB disruption from brain hemorrhage. J. Magn. Reson. Imaging 2009;29:31–38. © 2008 Wiley‐Liss, Inc.     

微泡造影剂介导的声空效应对胶质瘤大鼠血脑屏障通透性及替莫唑胺疗效的影响

目的 观察微泡造影剂联合超声对胶质瘤大鼠血脑屏障通透性及化疗药物疗效的影响.方法 通过透射电镜观察超微结构、Western blotting检测紧密连接蛋白claudin-5的表达、脑组织伊文蓝染色检测并确认影响Wistar大鼠血脑屏障通透性的最佳造影剂浓度及最佳超声模式.采用大鼠胶质瘤细胞系9L脑纹状体注射建立Wistar大鼠胶质瘤模型,予以替莫唑胺化疗(50mg/kg,连用5d)后,计算瘤体大小,ELISA检测血清中肿瘤标志物胶质纤维酸性蛋白(GFAP)的浓度.结果 微泡造影剂联合超声可使血脑屏障内皮细胞间的连接松弛,最佳造影剂浓度为1ml/kg,最佳超声模式为间隙触发(间隙400ms)10min;声空效应组大鼠中伊文蓝通过血脑屏障的含量明显多于对照组(P＜0.05).替莫唑胺化疗后,声空效应组肿瘤体积明显低于对照组,而血清G FAP浓度明显高于对照组(P＜0.05).结论 微泡造影剂联合超声可提高胶质瘤大鼠血脑屏障通透性及化疗药物的疗效.