脑血管病大脑局部血流量变化研究

本文对122例脑血管病人进行~(133)XE吸入法大脑局部血流量检查,研究脑梗塞及脑出血时脑局部血流量的变化,表现为脑血管病变部位局部血流量减少,并且变化范围较CT改变广泛,能在脑实质发生形态改变前测定出脑循环的改变。但无助于脑缺血与脑出血的鉴别诊断。     

磁共振脑机能成像

脑功能区被激活时，局部血流量增加，而耗氧量增加不明显。局部氧合血红蛋白和脱氧血红蛋白之间比例发生改变，Ｔ２·ＷＩ上局部信号随之变化，使磁共振观察脑机能活动成为可能。超高场强磁共振对局部磁化率的变化最敏感；超高速成像，如ＥＰＩ，可观察较大范围的功能区，而且能观察局部脑血流灌注；只是二目前尚不能广泛用于临床。高场强（１Ｔ￣２Ｔ）普通临床磁共振机，在视觉及运动中枢脑机能成像已取得满意结果，使脑机能成像     

脑肿瘤的组织间近距离放射治疗

组织间近距离放射治疗可提升脑肿瘤局部照射剂量,对于经过选择的原发和复发恶性脑胶质瘤及单发脑转移瘤患者,能提高局部控制率,延长生存期,且无严重的放射并发症,是一种安全、有效的辅助性治疗方法。     

内皮素A受体在颅脑创伤后脑微血管内皮细胞上的表达及意义

目的了解内皮素Ａ受体在颅脑创伤后脑微血管内皮细胞中的作用。方法对家兔致左额顶为着力部位的撞击伤，动态研究脑组织内皮素含量及内皮素Ａ受体ｍＲＮＡ表达和定位变化，内皮素Ａ受体拮抗剂ＢＱ１２３治疗效应，观察对脑创伤后局部脑血流量和脑含水量的影响。结果脑创伤后局部脑组织内皮素含量显著升高，内皮素Ａ受体ｍＲＮＡ表达显著增强，主要分布于脑血管内皮细胞；创伤后局部脑血流量下降、脑含水量显著升高，应用ＢＱ１２３治疗的动物，脑血流量下降和脑含水量升高被明显抑制。结论内皮素在颅脑创伤后脑水肿的形成中起重要作用，其作用是通过内皮素Ａ受体调节，应用内皮素Ａ受体拮抗剂可防治颅脑创伤后继发性脑水肿     

CT灌注成像在脑梗死前期局部低灌注中的应用价值

目的: 探讨脑梗死前期局部低灌注的CT灌注成像的价值.材料和方法: 分析15例临床诊断为脑局部缺血CT平扫和CT增强扫描,常规MRI、MRA及CT灌注成像的表现.结果: 15例CT平扫和增强扫描均未发现新的脑梗死灶,CT灌注成像发现脑梗死前期脑局部低灌注I1期4例、I2期7例、II2期3例,MRI发现缺血灶14个,MRA发现一侧大脑中动脉狭窄2例,一侧大脑中动脉闭塞1例.结论: 脑梗死前期局部低灌注,常规CT,MRI无异常发现.CT灌注成像可超早期发现脑组织局部血流动力学异常,并可分期区分低灌注的脑局部微循环的病理生理学状态,对临床治疗有重要价值.     

脑损伤后脑循环障碍的机制及其与脑水肿的关系

脑血液循环障碍是颅脑损伤病情发展的主要病理生理学基础之一,在继发性脑损害中起着重要作用。近来发现,颅脑损伤后存在脑缺血和脑充血两个过程,脑循环状态主要决定于脑血管阻力,而与脑灌注压关系不大［１３］。神经、代谢等诸多因素通过调节脑血管阻力而影响脑血流。笔者综述脑损伤后脑循环障碍发生的机制及其与脑水肿的关系。一、局部化学因素局部化学因素是指局部脑组织细胞摄取或释放一些化学物质,引起细胞间液成分改变,可以造成细胞膜电位、传导性发生改变,从而导致血管平滑肌细胞的收缩或舒张［４,５］。这种机制保证了脑细…     

放射性示踪剂在脑功能PET显像中的应用

脑PET显像是利用正电子示踪剂检测脑血流量,血容量,局部葡萄糖利用率,氧、氨基酸代谢和血脑屏障的完整性,以及受体的位置、密度和分布等。因此,PET不仅能研究各种脑疾病的过程和特征,评价神经系统疾病治疗效果,而且能研究正常脑功能。     

抑郁症脑局部血流灌注断层显像的半定量分析

抑郁症脑局部血流灌注断层显像的半定量分析李险峰邓红张承刚韩树杰韩钢应用脑ＳＰＥＣＴ研究抑郁症脑局部血流灌注断层显像，国内报道较少。本文总结了１１例抑郁症患者及１３例健康志愿者的ｒＣＢＦ半定量分析结果。１资料与方法１１病例选择我院精神卫生科住院１１例...     

脑梗塞神经功能联系障碍的研究

脑梗塞神经功能联系障碍的研究张生林马静萍张承刚脑梗塞的局部脑损害可以引起神经功能联系障碍。我们对１５０例脑梗塞患者进行了脑血流ＳＰＥＣＴ和脑电地形图（ＢＥＡＭ）检查，以观察其脑局部血流（ｒＣＢＦ）灌注和脑电活动的关系，现报道如下。资料与方法１临床资...     

基于弥散张量成像的脑结构网络增龄性变化研究

目的基于弥散张量成像及纤维束追踪技术构建大脑结构网络,研究大脑结构网络增龄性变化。方法分别构建30例青年人和30例老年人的脑结构网络。运用图论分析方法,计算脑结构网络的全局以及局部网络拓扑参数,定量分析年龄对大脑网络全局特性及局部特性变化的影响。结果研究显示人脑结构网络具有小世界属性,脑网络全局特征参数与年龄具有强相关性(P<0.05),平均节点度、局部效率以及全局效率随年龄增长呈明显下降趋势,而平均聚类系数和平均最短路径长度呈上升趋势。脑网络局部特性与大脑全局特性的变化具有一致性,其中右侧楔前叶、左侧颞中回、双侧前扣带和旁扣带脑回、双侧内侧和旁扣带脑回、左侧梭状回、左侧舌回、左侧距状裂等脑区存在显著老化现象。结论大脑网络信息传输效率随年龄的增长而降低,整体机能随年龄增长呈下降趋势,但在局部脑区有着不同的老化机制。     

外伤性迟发性脑内血肿的早期CT表现

目的　研究外伤性迟发性脑内血肿的早期CT表现 ,评价这些表现对迟发性脑内血肿的预期诊断意义。方法　搜集CT复查证实的外伤性迟发性脑内血肿 31例 ,对其首次CT检查及复查的CT影像特点进行分析。按时间顺序抽取脑外伤后复查无脑内血肿病人 5 0例作为对照。统计处理2组观察结果。结果　 31例迟发性脑内血肿首次CT检查主要异常表现包括 :(1)限局性脑实质密度减低 ,灰白质分界不清 18例。 (2 )限局性蛛网膜下腔出血 2 4例。 (3)局部脑轻度占位效应 16例。 (4 )硬膜下血肿 9例。统计学显示与无迟发性脑内血肿差异有显著性意义 (χ2 =4 5× 10 -10 ,2 7 98,19 5 7,10 5 4,P值均 <0 0 1)。同时盲法测试结果显示 ,作者与盲法观察结果差异无显著性意义 (χ2 =1 0 3,0 34 ,2 81,P值均 >0 0 5 )。结论　脑外伤后首次行CT检查 ,出现局部脑实质密度减低 ,灰白质分界不清 ;局部蛛网膜下腔出血及脑占位效应 ,提示此部位可能出现迟发性脑内血肿 ,应及时做CT复查     

冲击伤后大鼠马及脑干组织超微结构改变及其与肺冲击伤伤情的关系

比较观察了胸部局部或合身冲南伤后大鼠海巴和脑干组织超微结构改变及其与肺冲击伤伤情的关系。采用BST－Ⅰ和BST-Ⅲ型生物激波这分别致全身和胸部局部冲击伤,尸检显示,全身或胸部局部暴露冲击波仅导致明显的肺冲击伤,脑组织无明显的器质性损害。电镜结果显示,胸部局部或全身冲击伤后,海马和脑干神经细胞出现明显的结构改变,肺冲击伤伤情愈重,海马和脑干组织的超微结构改变也愈明显。提示全身或胸部局部冲击伤虽未引起脑组织肉眼上的明显损伤,但可造成海马和脑干组织超微结构的明显改变,并与肺冲击伤有一定的内在联系。     

Brain function and local anatomy for SPM analysis

The local brain function has been traditionally investigated based on the correlation of dysfunction with sites of brain lesions. The investigation of relationships between brain function and brain anatomy in both normal subjects and cooperative patients is now a reality through the advent of noninvasive brain monitoring techniques such as positron emission tomography using 15O-water and functional magnetic resonance imaging. While the development of those hardwares is taken for granted, it is quite necessary to deal with large amount of image data in a statistically accurate and rapid manner. Statistical parametric mapping (SPM) developed by Friston et al., is a standard method processing the image data in activation studies and now available world-wide. SPM can analyze multiple brains and display the activated site on the standard brain which is settled on Talairach's atlas in SPM95 and on MNI (Montreal Neurological Institute) template in SPM96 and SPM99. In activation study, it is most important to design the tasks that specifically enable the local brain areas to be active and elucidate the unknown local function. Thus we must realize in detail what has been known and not about local brain function.     

Locally induced hypothermia for treatment of acute ischaemic stroke: a physical feasibility study

During the treatment of stroke by local intra-arterial thrombolysis (LIT) it is frequently possible to pass the blood clot with a micro-catheter, allowing perfusion of brain tissue distally to the occlusion. This possibility allows for new early treatments of ischaemic brain tissue, even before the blood clot has been removed. One potential new approach to preserve brain tissue at risk may be locally induced endovascular hypothermia. Physical parameters such as the required micro-catheter input pressure, output velocity and flow rates, and a heat exchange model, applicable in the case of a micro-catheter placed within a guiding catheter, are presented. Also, a simple cerebral temperature model is derived that models the temperature response of the brain to the perfusion with coolant fluids. Based on this model, an expression has been derived for the time needed to reach a certain cerebral target temperature. Experimental in vitro measurements are presented that confirm the usability of standard commercially available micro-catheters to induce local hypothermia of the brain. If applied in vivo, the model predicts a local cooling rate of ischaemic brain tissue of 300 g of approximately 1°C in 1 min, which is up to a factor 30-times faster than the time-consuming systemic hypothermia via the skin. Systemic body temperature is only minimally affected by application of local hypothermia, thus avoiding many limitations and complications known in systemic hypothermia.     

The Role of Postoperative Radiotherapy after Resection of a Single Brain Metastasis

BACKGROUND AND PURPOSE: The extent of treatment in patients with single brain metastasis is a controversial topic. Especially the issue of whole-brain radiotherapy (WBRT) after local treatment of the lesion is largely unresolved. Therefore, the authors performed a pooled analysis of all available clinical data, based on a comprehensive literature search and on prospectively defined inclusion criteria and endpoints (in particular local brain control at the original site and development of new brain metastases). MATERIAL AND METHODS: Overall, 643 patients from ten publications met the inclusion criteria. 106 patients were treated with surgery alone, 66 with surgery plus local radiotherapy, and the others with surgery plus WBRT (Table 1). RESULTS: Both types of additional radiotherapy significantly improved local control at the original site (relative risk of local failure <0.5). WBRT also reduced new lesions significantly (relative risk 0.6). Within the available range of doses, no significant dose-response relationship was observed (Figure 1). Even after WBRT, new lesions remained the predominant type of brain failure. One of the underlying causes might be continuous reseeding of cells from active extracranial sites. Toxicity and quality of life were not well described in the publications. CONCLUSION: The present data favor moderate-dose WBRT, but the pros and cons of each option should be discussed with each patient. Higher radiation doses or local boost treatment are not supported by these data, but might be considered under certain circumstances, e.g., after incomplete resection.     

Development of quantitative analysis method for stereotactic brain image: Assessment of reduced accumulation in extent and severity using anatomical segmentation

Through visual assessment by three-dimensional (3D) brain image analysis methods using stereotactic brain coordinates system, such as three-dimensional stereotactic surface projections and statistical parametric mapping, it is difficult to quantitatively assess anatomical information and the range of extent of an abnormal region. In this study, we devised a method to quantitatively assess local abnormal findings by segmenting a brain map according to anatomical structure. Through quantitative local abnormality assessment using this method, we studied the characteristics of distribution of reduced blood flow in cases with dementia of the Alzheimer type (DAT). Using twenty-five cases with DAT (mean age, 68.9 years old), all of whom were diagnosed as probable Alzheimer's disease based on NINCDS-ADRDA, we collected I-123 iodoamphetamine SPECT data. A 3D brain map using the 3D-SSP program was compared with the data of 20 cases in the control group, who age-matched the subject cases. To study local abnormalities on the 3D images, we divided the whole brain into 24 segments based on anatomical classification. We assessed the extent of an abnormal region in each segment (rate of the coordinates with a Z-value that exceeds the threshold value, in all coordinates within a segment), and severity (average Z-value of the coordinates with a Z-value that exceeds the threshold value). This method clarified orientation and expansion of reduced accumulation, through classifying stereotactic brain coordinates according to the anatomical structure. This method was considered useful for quantitatively grasping distribution abnormalities in the brain and changes in abnormality distribution.     

Spatial registration of digital brain atlases based on fuzzy set theory.

We present a semiautomatic method based on fuzzy set theory for adjusting a computerized brain atlas to magnetic resonance images (MRIs) of the human cerebral cortex. The atlas was registered to three-dimensional MRI data sets of 10 healthy volunteers. After a global matching using the external contour of the brain, several local procedures were performed regarding selected primary furrows and cytoarchitectonic areas. The final transformation matrix was calculated with respect to these anatomical structures and to their local matrices. Evaluation revealed an increase in accuracy as expressed by a reduction of the visible mismatch with respect to the registration of cortical and subcortical brain structures.     

Confirmation of brain death in the emergency department

When a patient is brought to the emergency department with profound coma, absent brain stem reflexes, and apnea, the possibility of brain death should be considered. If this condition is irreversible, the patient meets the clinical criteria and may be declared dead. Prompt confirmation is important: valuable resources can be redirected to living patients, the decedent’s family can be given ministry, and transplantation of donor organs to needy patients can be facilitated. Although brain death is a clinical diagnosis, confirmation by additional testing is often required by local practice standards or local law. This article discusses the role of the radiologist in this situation and the examinations used for this purpose.     

Electromagnetic and modeling analyses of an implanted device at 3 and 7 Tesla

PURPOSE: To study the specific absorption rates (SAR) associated with implantable devices at 3T and 7 T. MATERIALS AND METHODS: Studies were carried out utilizing a finite difference time domain (FDTD) model that treats the radio frequency (RF) coil and an anatomically detailed human head mesh as a single system. Analyses were performed at 3 T and 7 T for different orientations and positions of an implanted (in the brain) aneurysm clip. Studies were also performed for two different types of FDTD mesh of the same aneurysm clip. RESULTS: The results showed that: 1) the electromagnetic effects of implanting the aneurysm clip (in the brain) is mostly local on SARs; and 2) orientations of the implanted aneurysm clip have considerable effect on the local SARs near the implanted clip; the level of such an effect can also vary significantly between 3 T and 7 T. CONCLUSION: In general, the presented study shows that the local SARs (in 1 g and in 10 g of tissue) near the implanted aneurysm clip are lower than the peak SARs (due to the standard RF coil operation) in other regions of the human head mesh/brain. For specific orientations, however, if the aneurysm clip is implanted in a region in which the brain peak-SAR occurs due the standard RF coil operation, the brain peak SAR increases further. This is more prevalent at 7T compared to 3T. Additionally, it was also found that basic structured and Cartesian FDTD modeling produces relatively higher local SARs than that obtained with simple non-Cartesian FDTD modeling.