磁共振灌注及弥散成像在早期脑梗塞诊断的价值

磁共振弥散加权成像和血流灌注成像不仅可以超早期诊断脑梗塞，明确缺血部位，范围，估计缺血半暗带的大小和鉴别短暂性脑缺血发作；特殊磁共振序列还可以确诊早期颅出血，有助于溶栓对象的筛选和预后的判断。为溶栓治疗提供直观的影像学依据。     

慢性酒精中毒性脑病磁共振及功能性成像分析

目的探讨慢性酒精中毒性脑病磁共振及功能性成像改变.方法总结32例慢性酒精中毒性脑病的患者,分别进行磁共振常规平扫、磁共振弥散成像、磁共振波谱成像分析.结果 32例患者均有不同程度的精神异常,表现为脑萎缩、脑白质脱髓鞘.磁共振弥散成像为高信号,表观扩散系数ADC图为低信号,磁共振波谱成像显示病变部位氮乙酰天门冬氨酸(NAA)以及胆碱(Cho)显著减低.结论磁共振及其功能性成像对酒精性脑病的诊断、判断治疗及预后评价具有重要价值.     

肝细胞癌的CT和MRI研究进展

肝细胞癌(hepatocellular carcinoma, HCC)是世界上第六大常见癌症。计算机断层扫描(computed tomography, CT)和磁共振成像(magnetic resonance imaging, MRI)是目前可实现HCC无创诊断的最佳成像技术。成像在HCC的早期检测、准确分期和规划管理策略中发挥着至关重要的作用。根据近年来国内外公开发表的相关文献，分析传统肝脏CT成像和MRI成像的优缺点，并对一些成像模式如双能CT、灌注CT、基于人工智能的方法、磁共振弥散加权成像、弹性成像、灌注加权成像、扩散峰度成像以及波谱成像的原理、优缺点和临床研究进展等进行系统概述，为进一步推进HCC的诊疗提供一定的参考。     

磁共振诊断早期脑缺血的新技术进展--弥散加权成像及灌注加权成像(综述)

磁共振弥散加权成像（ＤＷＩ）和血液灌注成像（ＰＷＩ）是诊断早期脑缺血的新技术；表现弥散系数、脑血流、脑血容量及平均时间是预测缺血灶结果的参数，本文综述了ＤＷＩ及ＰＷＩ的基本原理、测定技术及它们在诊断早期脑缺血方面的应用，分析了ＤＷＩ及ＰＷＩ在诊断早期脑缺血方面的相互关系，认为ＤＷＩ及ＰＷＩ能对早期脑缺血出诊确诊断信息，可反映缺血灶血流动力学的改变。     

用PC机处理磁共振弥散张量数据示踪三维脑白质纤维束

目的:使用磁共振弥散张量成像和示踪技术进行三维脑白质纤维束示踪成像.方法:对8名健康自愿者进行头部磁共振弥散张量检查,使用弥散加权-回波平面成像序列(重复时间8 000 m s,回波时间80 m s),b值为1 000 s/mm2,25个弥散方向,扫描层厚4 mm,无间隔,矩阵120×120,扫描野24 cm.使用PC机软件分析弥散张量数据并示踪三维脑白质纤维束成像.结果:每例实验对象的三维示踪结果显示连合系、联络系和投射系各种脑白质纤维束的结构和其在三维空间的走行,与解剖学所描述相对比基本一致.结论:使用磁共振弥散张量三维脑白质纤维束示踪可以立体直观地显示各种脑白质纤维束.不仅可以用于解剖学教学,还可进一步应用于临床,对部分神经系统疾病的辅助诊断有潜在的应用价值     

海洛因中毒性脑病的生理特点与DWI表现

目的分析和探讨海洛因中毒性脑病的生理病理特点及DWI表现.方法对6例海洛因中毒性脑病患者行头颅磁共振弥散加权成像(DWI).结果可见双侧小脑、内囊后肢、枕顶叶深部白质、胼胝体、脑干等白质区域异常信号,常规MRI为长T1长T2信号,DWI弥散加权图呈高信号.结论根据海洛因中毒性脑病生理及病理特点行DWI可对本病早期诊断.     

融合白质功能信号的DWI纤维优化重建

磁共振弥散加权成像(DWI)可对大脑白质纤维束的结构连通性进行无创研究,其主要方法为DWI纤维重建.并且基于DWI的结构连接常常与基于功能磁共振成像的功能连接相结合,以得到纤维重建的最优路径.本文提出一种融合白质fMRI,将功能信号作为先验信息进行DWI纤维全局优化重建的方法,获得表征描述特定功能结构的最优纤维路径.实验结果表明,加入fMRI功能先验信息的优化方法可重建出具有功能意义的白质纤维束,较之现有的纤维重建方法具有更高的可靠性和鲁棒性.     

磁纳米分子影像探针研究热点与挑战

 近年来,磁纳米材料在分子影像领域的应用得到科研人员的广泛关注。常用的磁性纳米探针是超顺磁性氧化铁颗粒（SPION）,它具有较好的水质子横向弛豫时间（T₂）弥散加权核磁共振成像造影剂的性能。通过对SPION制备及表面修饰进行改进,使纳米颗粒具有磁共振造影功能和干细胞标记、药物/基因递送的功能。综述了SPION兼具影像探针和磁共振成像可视化治疗方面的功能。虽然已有多种磁纳米材料进入临床研究,但结合当前研究瓶颈以及纳米药物制备方法的发展,制备造影效果较好、药物生物相容性较高、具有靶向性及临床转换潜力较强的SPION是新一代磁纳米探针研究亟需解决的问题。     

功能磁共振用于肿瘤光热和光动力协同治疗的实时监测研究

将实验动物分为光热治疗组、光动力治疗组、光热和光动力协同治疗组,使用T2加权和扩散加权两种磁共振成像方式对治疗效果进行实时监测,并使用病理学方法对磁共振检测效果进行验证.实验结果发现,两个单纯治疗组中肿瘤并未被完全杀灭;而协同治疗组中,肿瘤被完全杀灭.磁共振作为无创监测手段,在疗效评价中有巨大的应用价值,并可对纳米粒子的设计合成起到指导作用.     

DWI和DTI对腰椎间盘早期退变的诊断价值

目的:探讨应用磁共振弥散加权成像( DWI)和弥散张量成像(DTI)判别腰椎间盘早期退变的可行性.方法:青年志愿者40例(均无腰痛和腰椎部畸形、外伤、手术病史),行腰1(L1)～骶1(S1)椎间盘DWI和DTI扫描,生成表观弥散系数( ADC)和部分各项异性(FA)伪彩图.在腰1/2(L1/2)～腰5/骶1(L5/S1)的各个椎间盘髓核内放置5点感兴趣区( ROI),测量ADC值和FA值.分析并比较腰椎间盘髓核表观弥散系数(ADC)值和部分各项异性(FA)值差异.结果:ADC值和FA值在同一椎间盘内的不同区域或不同椎间盘平面内的对应区域存在差异(P＜0.05);椎间盘平均ADC值与解剖部位相关,腰4/5(L4/5)和L5/S1椎间盘ADC值明显增高(P＜0.05);FA值在不同椎间盘平面内的对应区域,随解剖部位位置的降低有升高的趋势,L5/S1椎间盘FA值升高最明显(P＜0.05).结论:ADC值和FA值能体现椎间盘水分子弥散能力的变化,量化反映椎间盘退变早期髓核的生化状态.DWI和DTI技术可以对腰椎间盘早期退变的诊断提供影像学依据,并有助于理解椎间盘退变的发生机制.     

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.     

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.     

基于功能磁共振成像的网络连接显示方法

探讨了基于功能磁共振成像的功能连接图和有效连接图的显示方法,并在Matlab环境下编写界面实现了该方法.     

Visualizing columnar architectures using high-field fMRI

Among the many neuroimaging tools available for studying human brain functions, functional magnetic resonance imaging (fMRI) is the most widely used today. One advantage of fMRI over other imaging techniques is its relatively high spatial resolution. High-resolution fMRI, with its superb signal-to-noise ratio and improved tissue-vessel specificity, has strengthened the capability of fMRI and allowed mapping of fine cortical architectures in the human brain. In this review, I will first explain the factors limiting the spatial specificity of the blood oxygenation level-dependent (BOLD) effect, based on which most of fMRI experiments are conducted, and the measures dealing with these factors, and then briefly introduce several high-resolution (sub-millimeter) studies on the functional organization of human primary visual cortex (V1), including mapping of ocular dominance columns, mapping of temporal frequency dependent domains and direct demonstration of tuning to stimulus orientation.     

Visualizing columnar architectures using high-field fMRI

Among the many neuroimaging tools available for studying human brain functions, functional magnetic resonance imaging (fMRI) is the most widely used today. One advantage of fMRI over other imaging techniques is its relatively high spatial resolution. High-resolution fMRI, with its superb signal-to-noise ratio and improved tissue-vessel specificity, has strengthened the capability of fMRI and allowed mapping of fine cortical architectures in the human brain. In this review, I will first explain the factors limiting the spatial specificity of the blood oxygenation level-dependent (BOLD) effect, based on which most of fMRI experiments are conducted, and the measures dealing with these factors, and then briefly introduce several high-resolution (sub-millimeter) studies on the functional organization of human primary visual cortex (V1), including mapping of ocular dominance columns, mapping of temporal frequency dependent domains and direct demonstration of tuning to stimulus orientation.     

联合独立成分分析和典型相关分析盲分析fMRI数据

为了自动识别功能信号成分,通过对灰质数据和脑脊液数据独立成分的空间相关性进行典型相关分析,有效地解决了独立成分的排序问题.提出的方法不需要任何先验信息,能够稳健地识别与实验设计相关的功能信号成分,实现了对fMRI数据的盲分析.通过对临床真实fMRI数据的分析,阐明了提出方法的有效性及可靠性.     

基于高场3T磁共振的人体组织电特性成像

结合现代的影像学方法,提出了一种基于磁共振成像的生物组织电特性成像方法.根据磁共振图像扫描信号中包含目标体的电导率和介电常数等信息这一原理,从法拉第定律和安培定律出发,推导出了激励射频磁场与电特性之间的关系.利用基于双角度法的自旋回波扫描序列,对志愿者头部进行了高场3 T下的磁共振成像实验,初步得到了质子密度像、射频场映像以及相应的电特性像.改进的算法中引入梯度项后,图像上不同组织内部的电特性变化更加明显.与传统电阻抗成像以及常规磁共振成像相比,本文的新型磁共振电特性成像兼具高对比度和高分辨率的特点,作为一种功能成像,有望在相关重大疾病的预防和诊断方面发挥作用.      

Multifractal analysis of resting state fMRI series in default mode network: age and gender effects

Age-related changes of resting state in default mode network （DMN） may provide new clues to the developing mechanism of normal brain as well as early diagnosis and therapy of some neuropsychiatric disorders. The application of multifractal theory to functional magnetic resonance imaging （fMRI） signals has recently raised increasing attention. We aim to explore the multifractal characteristics underlying the resting state functional magnetic resonance imaging （rs-fMRI） series extracted from DMN, and two issues are mainly discussed： （1） whether there exist multifractals in rs-fMRI series; （2） whether it is possible to distinguish between the different ages or genders by means of multifractal characteristics. Results demon- strated the existence of multifractals in rs-fMRI series in DMN. In addition, slight differences between young subjects and middle-aged or elderly subjects can be successfully detected by △asα, a modified measure we proposed. Furthermore, it is revealed that the rs-fMRI series from young subjects possess smaller averaged scale index and weaker long range correlation, while those from middle-aged or elderly people present increasing averaged scale index andstronger long range correlation. Whereas no significant statistical differences has been found between male and female group. Our results, therefore, highlight the potential useful- ness of multifractal analysis in fMRI series of a certain brain region, and provide important insights into healthy aging in DMN.     

Diagnosis of prostate cancer by quantitative analysis of 3DMRSI data: A new model

Three-dimensional magnetic resonance spectroscopic imaging (3DMRSI) is helpful to identify prostate cancer (PC)from benign prostate hyperplasia (BPH) and to show the distribution of tumor infiltration. Combined with the (Cho + Cre)/Cit ratio, the z-score model can effectively discriminate prostate cancer from stromal benign prostate hyperplasia (sBPH) and detect small malignant lesions (SML).