这项工作的组成部分， 即损坏的梯度方向多动障碍的患者在应用程序的数据质量控制和校正的研究，支持欧洲高清网络（EHDN项目070个）。这一定研究的MRI扫描获得伦敦站点TRACK-HD队列的一部分。

分析方法：预处理和后处理下面的协议的任务是分析的属性内voxelwise的白质，这可能是扩散 - 由于检测voxelwise - 各向同性或各向异性，从而导致长球形或扁圆形的各个体素的弥散张量。用于FA-地图或计算的的fibertracts识别（ 图1）中的参数设置的体素张量。 为了获得分析结果显示在下面的，使用的软件包的张量成像和纤维的跟踪 （TIFT）17。 TIFT提供分析工具，用于下列要求： <ul><li>分析在DTI的指标， 如 FA地图方面， </li><li>立体正常化</li><li> FA或其他DTI指标组比较</li><li>各种分析方法的FT </li><li> FT组平均ðTI的数据和相应的统计分析。 </li></ul>这些特性允许在一个软件环境17,29,30,31各种分析。的TIFT软件不断发展DTI数据分析中的新选项。 图2给出了原理概述如何分析DTI数据后空间正常化两种互补的方法， 即在组级别的WBS和TFAS最终获得受样品之间的差异，在集团层面， 如与健康对照组的害病的脑子。这里，网路自助服务的目标是在voxelwise公正的检测领域在组级别的差异，而TFAS根据预先定义fibertracts的; TFAS启动区域可以自由选择或可以从网路自助服务的结果（`热点`显着改变FA）。 个人纵向比较FA地图是由探测器汀在FA图测量的差异仿射立体定位对准后在不同的时间点（ 图2）。 <ol><li> 质量检查（QC）包括损坏的梯度方向修正 在收购过程中， 即在卷损坏的情况下运动的干扰的情况下，增加信噪比省略单梯度方向（GD）张计算。为了这个目的，32质量检查（QC）的算法被开发了。简单地说，含有损坏的卷的扫描中，信噪比（SNR）的增加来实现省略单梯度方向张量估计之前的某个时间：每个GD的加权方差进行加权计算序列中的所有剩余的方向与角度它们不同的索引好。 <ol><li>执行伪影校正， 即通过检测GD至少一片强度下降所造成的运动伪影自发SU<html>了对象的运动（ 图3，上面板 ）。对于任何弥散加权量，计算对于每个片层的平均强度，其强度比较通过使用加权平均的方法具有相同的切片在所有其他卷 - 的权重系数是GD的两个矢量的点积<img alt="式（8）" fo:src="/files/ftp_upload/50427/50427eq8highres.jpg" src="/files/ftp_upload/50427/50427eq8.jpg" /> ： <img alt="式（9）" fo:src="/files/ftp_upload/50427/50427eq9highres.jpg" src="/files/ftp_upload/50427/50427eq9.jpg" /> <img alt="公式10" fo:src="/files/ftp_upload/50427/50427eq10highres.jpg" src="/files/ftp_upload/50427/50427eq10.jpg" /> <img alt="式（11）" fo:src="/files/ftp_upload/50427/50427eq11highres.jpg" src="/files/ftp_upload/50427/50427eq11.jpg" />表示的算术平均强度下观察切片427eq12.jpg“/&gt;片作比较。相对平均强度偏差<img alt="式（13）" fo:src="/files/ftp_upload/50427/50427eq13highres.jpg" src="/files/ftp_upload/50427/50427eq13.jpg" />加权的GD的点积。因此，为了定义一个全局参数： <img alt="式（14）" fo:src="/files/ftp_upload/50427/50427eq14highres.jpg" src="/files/ftp_upload/50427/50427eq14.jpg" /> 至少反映了所有切片的slicewise比较。 </li><li>如果Q是根据一定的阈值（在本例中，0.8的阈值是用于此目的），消除该全卷的，或GD。 0.8的阈值被认为是一个稳定的解决方案32。图3可见矢状重建运动伪影和检测质量控制算法。在这个例子中，满分GD（ 图3c中的蓝色的点）的总数，有17人红线下面对应为Q = 0.8和寿LD被淘汰。在图3d的体积消除统计信息的一个例子为一个整体的研究。在这个示范性的研究，DTI症状前29高清科目的数据进行了比较，DTI数据30控制。进一步的细节在此算法中，在32，33。 </li></ol></li><li> 预处理和空间正常化 <ol><li>涡流引起的几何失真的回波平面成像数据集由34所提出的方法进行修正。 </li><li>对于脑立体定位的正常化，创建一个特定的研究（β= 0） -模板，如前面所述17,28,31 FA模板。基本上，一个完整的非线性的立体正常化由3个变形分量。因此，所得的弥散张量<img alt="公式15" fo:src="/files/ftp_upload/50427/50427eq15highres.jpg" src="/files/ftp_upload/50427/50427eq15.jpg" />的每个像素i的rotat根据上面列出的（ 图4）的所有的旋转： <ol class="lroman"><li> 图4a示出了一个刚性的脑对齐的基本坐标系的变换。的旋转<img alt="式（16）" fo:src="/files/ftp_upload/50427/50427eq16highres.jpg" src="/files/ftp_upload/50427/50427eq16.jpg" />产生的基本坐标系对准已被应用 <img alt="式（17）" fo:src="/files/ftp_upload/50427/50427eq17highres.jpg" src="/files/ftp_upload/50427/50427eq17.jpg" /></li><li> 图4b所示的线性变形，根据标志性建筑。的特征向量的组件<img alt="方程（5）" fo:src="/files/ftp_upload/50427/50427eq5highres.jpg" src="/files/ftp_upload/50427/50427eq5.jpg" />根据六个线性变形的S（取决于对大脑的一个区域中，a = 1 ... 6）的归一化参数都必须进行调整。 V W，J </sub&gt;&#39;&#39;&#39;是一个V W，J&#39;&#39;&#39; W = 1,2,3和 j = X，Y，Z。 </li><li> 图4c示出了非直线的非线性的脑的形状差异均正常化。导致一个单独的变换，可为每个像素的3-D的体素阵列为每个像素的3-D矢量的变化是不同的<img alt="式（18）" fo:src="/files/ftp_upload/50427/50427eq18highres.jpg" src="/files/ftp_upload/50427/50427eq18.jpg" /> ）。标准的三角函数给出了一个独立的旋转矩阵为每个像素，产生3-D矢量的变化，以维护邻居的体素的特征向量的方向之间的关系的概念16。因此，不同的两个相邻体素的变化导致对应的特征向量旋转。使用扩张矩阵的张对齐<img alt="公式15" fo:src="/files/ftp_upload/50427/50427eq15highres.jpg" src="/files/ftp_upload/50427/50427eq15.jpg" />的每个体素，以周围的体素。 <img alt="式（19）" fo:src="/files/ftp_upload/50427/50427eq19highres.jpg" src="/files/ftp_upload/50427/50427eq19.jpg" /> <img alt="式（20）" fo:src="/files/ftp_upload/50427/50427eq20highres.jpg" src="/files/ftp_upload/50427/50427eq20.jpg" />的组成部分是<img alt="式（18）" fo:src="/files/ftp_upload/50427/50427eq18highres.jpg" src="/files/ftp_upload/50427/50427eq18.jpg" /></li></ol>迭代整个归一化处理， 即建立一台扫描仪和序列特异性（二= 0） -模板本研究在第一步骤中通过算术平均（β= 0） -根据手动的线性变换后的所有主题的卷设置标志性建筑。这第一个归一化后，创建改进的模板，以优化的归一化矩阵。以下步骤1.2.3至1.2.5是示意性地显示在图5a。 </li><li>这个个体正常化过程后（STEP（I） -贸工部数据I 0），使用所有个别DTI数据集创建一个特定的研究（B = 0） -模板和FA-模板（步骤（ii） -模板T 1）。作为非仿射登记的FA-模板具有的优点是它提供了更高的对比度相比，（二= 0）的图像10，FA模板定义的平均单独来自FA-患者和对照的地图。 </li><li>阿什伯纳和Friston 35的基本思路，在第二步骤中，执行一个非线性MNI的归一化（步骤（iii））的DTI的数据的设置由尽量减少区域FA地图强度之间的不匹配将嵌合和FA-的模板根据平方差（X 2） -这样，你得到英国贸工部的数据I 1。 </li><li>基于这些数据，来自新模板T 2（步骤（iv））。重复这个反复的过程，直到个别FA地图和t之间的相关性他FA-模板&gt; 0.7。通常这两个迭代后达到。 </li></ol></li><li> 全脑为基础的空间统计 以下步骤1.3.1至1.3.5的可视化示意性地在图5b中。 <ol><li>计算FA地图1.2正常化过程归DTI数据。为了维护的方向信息（步骤（i））。 </li><li>作为统计比较voxelwise之前的预处理步骤，适用于平滑滤波器（步骤（ii））的各个归一化FA地图。对于平滑，过滤器的大小影响的事实，DTI数据分析36的结果需要匹配滤波器定理指出，用于对数据进行处理的过滤器的宽度，应根据所预期的差值的大小的应用程序，详细在以前的应用DTI数据与神经退行性疾病的患者（ 如 28）。 </li><li>执行统计小样图埃里森之间的患者群体和相应的对照组voxelwise学生的t检验， 即患者的FA地图控件的FA地图FA值比较FA值，分别为每个像素（步骤（iii ））。 FA值低于0.2的计算不考虑，因为灰质显示FA值可达0.2 37。 </li><li>统计结果都必须在校正多重比较，使用假发现率（FDR）算法在p &lt;0.05 38（步骤（iv））。要执行的空间相关性的算法（聚类 - 步骤（v）），消除孤立体素或像素的平滑核的大小范围的小型的，孤立的组的α误差进一步降低，导致512的阈值的簇大小体素。 </li><li>为了显示形态背景上的结果（步骤（V）），正常化的3-D T1加权数据集到MNI空间和平均算术。执行本正常化p通过使用类似于应用于DTI数据正常化的研究特定的模板设置rocedure 17。 </li></ol></li></ol> 图6显示了全脑为基础的空间统计（网路自助服务）的ALS患者与对照组的结果。 图6a显示了当地最大的一个矢状FA值下降，coronar和轴向视图（阈值（P &lt;0.01），校正多个比较）。 图6b所示projectional的FT TFAS基础作为皮质脊髓束的出发点。 图6c显示了基于空间统计（网路自助服务）之间的ALS患者和匹配的对照样品检测全脑组间差异FA地图可视化一个slicewise。 <ol start="4"><li> 束成像和各向异性分数统计tractwise的（TFAS） 图7示出基于组的FT的过程中，包括1所述的TFAS。4.1 1.4.4。 <ol><li>为了应用基于组的FT算法，生成平均DTI数据，一起根据前面所述的方法17套从病人的数据和控制数据。这种平均正常化过程中保留16所描述的技术取向的信息，这是需要慎重对待的-详细信息，请参阅30。 </li><li>执行跟踪技术学科组平均DTI数据集应用程序的简化跟踪技术31。识别手动定义种子点相邻的局部极大值的基于全脑FA分析是连续FT分析的基础。识别后的种子，进行纤维束和定义的掩模对TFAS以下30作为特定组的划定纤维的体素。 </li><li>为了量化跟踪技术的结果，应用该技术的TFAS日ê纤维束上创建的平均DTI数据集各学科各组（患者数据和控制数据）像素之间的比较病人和控件的FA地图的选择。 </li><li>考虑学生的t检验进行统计分析与FA值在0.2以上的所有体素。 </li><li>如果需要，TFAS技术可以应用于任何派生DTI度量，如平均扩散率（MD），径向各向异性，轴向各向异性等（例如，请参阅28）。 </li><li>的结果显示在MNI的归一化的3-D T1加权的数据集组成的形态的背景</li></ol></li></ol>

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DTI数据可以实现跨学科的平均与的扩散幅度（由利用足总杯信息）和扩散方向（根据FT）就分别。平均FA地图允许学科组统计比较的WBS和TFAS。这种方法论框架给出了一个介绍DTI技术跨学科平均组比较。的立体定向正常化和FA图在组级别允许比较几种可能性学科组之间的差异进行量化。网路自助服务和TFAS似乎是遗嘱的方式来测量组受试者在集团层面的差异与大脑的改变， 如神经退行性疾病的...

弥散张量成像技术在人类大脑 在中枢神经系统的白质（WM）大片密密麻麻轴突除了各种类型的神经胶质和其他小的细胞群体组成。轴突膜以及对齐的蛋白质纤维轴突内限制水的扩散垂直于纤维取向，导致脑WM 1中的各向异性水扩散。髓鞘的轴突周围也可能有助于各向异性的两个内和细胞外的水2。 扩散张量成像（DTI）可检测到这种各向异性的定量描述。 DTI生产组织与当地的微观结构特征的水扩散加权图像。的图象在每个位置上的强度衰减，根据所谓的磁扩散梯度的强度和方向（表示在b值），以及本地的显微组织，其中的水分子扩散，扩散系数 D，一个标量值： <img alt="公式1" fo:src="/files/ftp_upload/50427/50427eq1highres.jpg" src="/files/ftp_upload/50427/50427eq1.jpg" /> 然而，在WM中的各向异性的存在下，扩散可以不再其特征在于由一个单一的标量系数，但要求一个张量<img alt="等式（3）" fo:src="/files/ftp_upload/50427/50427eq3highres.jpg" src="/files/ftp_upload/50427/50427eq3.jpg" />在第一近似描述分子的流动性，沿各个方向，这些方向之间的相关性4。扩散的各向异性的原因，主要是通过WM中的纤维束的方向和由它的微观和宏观结构的功能的影响。的微观结构特征，出现intraaxonal组织扩散各向异性的影响最大，除了纤维的密度一ND细胞包装，髓鞘化程度，纤维直径和个人。在宏观尺度上的变异的方向在成像体素的所有WM大片影响其各向异性度5。 在典型的DTI测量，体素的尺寸以毫米的顺序。因此，总是包含一个体素的平均信息，检测到的，通常包括一些轴突，以及周围的水分子的体积内部的水分子。尽管这种多向环境，DTI是敏感的最大主轴线对齐的主要轴突方向的方向， 即轴突的贡献占主导地位的被测信号2。 英国贸工部提供两种类型的水扩散的财产的信息：第一，独立的方向扩散各向异性和第二的程度，水扩散成像的主要方向É体素， 即的扩散方向6。 目前的协议都应该DTI分析技术学科组在组级别的定量比较提供了一个框架，概述如下。 扩散性能的定量分析-分析参数 对称张量的元素可以通过扩散梯度沿至少6个非共线和非共面的方向进行测量，以便使得b（ 等式1）已成为一个张量，从而导致信号的衰减<img alt="公式（2）" fo:src="/files/ftp_upload/50427/50427eq2highres.jpg" src="/files/ftp_upload/50427/50427eq2.jpg" /> 这个方程需要占成像和扩散梯度，应用正交方向（交叉）之间，甚至应用的成像梯度之间可能的相互作用在正交方向4。 排名第二的扩散张量<img alt="等式（3）" fo:src="/files/ftp_upload/50427/50427eq3highres.jpg" src="/files/ftp_upload/50427/50427eq3.jpg" />总是可以被对角化离开只有三个沿主对角线张量的非零元素， 即特征值（ <img alt="式（4）" fo:src="/files/ftp_upload/50427/50427eq4highres.jpg" src="/files/ftp_upload/50427/50427eq4.jpg" /> ）。特征值反映椭球的形状或结构的。所描述的特征向量之间的数学关系的主坐标系中的椭球和实验室帧<img alt="方程（5）" fo:src="/files/ftp_upload/50427/50427eq5highres.jpg" src="/files/ftp_upload/50427/50427eq5.jpg" />由于存在多种挑战，显示张量数据，扩散椭球的概念已经提出了3。这些电子Eigendiffusivities的llipsoids指在介质中的扩散系数的影响的主要方向的一维扩散系数椭圆体的主轴线， 即表示主扩散方向与纤维的方向相一致的体素，而椭球的偏心率提供了有关程度的各向异性和其对称性。因此，扩散各向异性的各向异性分数（FA）的指标，如可以定义7。 <img alt="公式（6）" fo:src="/files/ftp_upload/50427/50427eq6highres.jpg" src="/files/ftp_upload/50427/50427eq6.jpg" /> <img alt="式（7）" fo:src="/files/ftp_upload/50427/50427eq7highres.jpg" src="/files/ftp_upload/50427/50427eq7.jpg" />是所有特征值的算术平均值。 另外一个方法是使用解决洗衣机的连通性大脑的主要方向上的弥散张量，对应于跟踪技术的做法通道具有彼此连接的部位的脑的意向调查。假设的主要成分的方向的弥散张量表示占主导地位的方向轴突大片，矢量场的3-D，其中每个向量表示的纤维取向。目前，有几种不同的方法来重建可分为两种类型：第一类是基于线传播算法使用本地张量信息的每个步骤中的纤维束的传播2,8,9洗衣机大片。第二类是基于全局能量最小化的能量上最有利的路径之间的两个WM区域，导致道为基础的空间统计方法（TBSS）10中使用的其它算法，如各向异性分数统计tractwise（TFAS已 - 看到协议文本，第2.4节）。 立体立场的转化ARD空间像其他先进的磁共振成像方法，DTI和FT为基础的研究，在临床情况下追求的最终目标，个别病人的脑形态进行分类，以促进诊断过程中，基于一些歧视度量11。在组级别的研究是最常见的临床表型相关的，如果被认为是由于损坏一个或多个特定脑区域或特定的神经解剖学网络。这里，不同科目的平均业绩是有用的，以评估微观结构改变的常见模式。每个单独的大脑有要传输到立体的空间中，这样，在第二步骤中，在体素的体素水平的算术平均的结果是可能的。空间标准化允许从不同的受试者中获得的结果，以提高信号噪声比（SNR），并进行比较，样品的患者和续算术平均的ROLS，以便分析计算pathoanatomy特定的疾病， 例如做作，这是与一个特定的大脑系统的神经变性疾病。 早期的做法规范化，标准化的立体空间12建议变换算法涉及识别各种脑头痛医头，脚痛医脚的地标和缩放脑象限的标准图集。如今，最先进的磁共振成像数据分析软件包使用正常化蒙特利尔神经学研究所（MNI）立体空间13。对于这种转变，半自动和自动化的大脑登记算法研究特定的模板，开发出14,15。在英国贸工部，特别注意的绘制过程中保持方向信息的正常化进程16,17。 DT-MR图像的空间变换中的应用所必需的空间标准化数据集的集合，翘曲标量图像，并发DT的一个事实，即包含取向信息，再次通过转换的影响相反。此效果，必须考虑，以确保转换后的图像的解剖的正确性。这里，DTI数据集应用仿射变换的技术。 DTI脑部疾病中的应用 纵向DTI数据的比较需要一个主体彼此之间的数据对齐/注册。在这方面，方向信息的保存是必要的（ 即在仿射变换的弥散张量的旋转）。神经退行性疾病的可能的应用已被以前的报告（ 例如，18,19）。 英国贸工部已被确立为一个强大的非侵入性的技术工具， 在体内神经病理学调查OGY的WM神经大片（ 例如 11,20,21,22）。的扩散过程的DTI的定量度量， 例如，在FA，已经被示出是敏感的标志物，用于学习一个宽范围内的WM病理学，如中风20，多重硬化症23，肌萎缩性脊髓侧索硬化症24，25，阿耳茨海默氏病26和几个其他WM障碍的27,28。 此外，DTI可用于与FT识别WM大片23。这种技术，而仍然没有在常规临床使用，正在评估途径特异性异常，神经系统疾病的一个强大的工具。在所确定的大片，各种来自英国贸工部和额外的收购（ 如 T2加权图像和/或磁化传递（MT）成像）MRI定量指标，解剖配准贸工部的数据可以衡量的。因此，每个索引可以演算ATED道内的位置作为一个函数，指情节描绘道型材的空间变化。 在下面的，人类的DTI扫描上进行1.5特斯拉核磁共振扫描仪（德国埃尔兰根西门子医疗）被用来研究各种分析技术检测脑白质异常病人团体以及个人的潜力。消除运动等各类文物损坏的卷和卷的自动质量检查后，标准化的后处理程序准备DTI数据连续分析。在下面将说明不同的分析方法， 即第一，整个大脑的空间统计（网路自助服务），第二，FT，第三，Tractwise的各向异性分数统计（TFAS）。网路自助服务是运行在基于体素的形态学（VBM），通常被称为基于体素的形态学测量/ DTI数据统计（VBM / DTI比喻的方法） <e米。VBM是最初运行在对比度的图像对比度差异在单独的扫描中必须加以解决，而网路自助服务是一种方法，该方法使用voxelwise的一个物理参数的比较的方法。因此，虽然算法类似，区分网路自助服务和VBM术语将在下面使用。

<table border="1">
 <tbody>
 <tr>
 <td>MR scanner</td>
 <td></td>
 <td></td>
 <td>Siemens 1.5 T Magnetom Symphony</td>
 </tr>
 <tr>
 <td>analysis software </td>
 <td></td>
 <td></td>
 <td>TIFT - Tensor Imaging and Fiber Tracking</td>
 </tr>
 </tbody>
 </table>

diffusion tensor magnetic resonance imaging in the analysis of neurodegenerative diseases

弥散张量成像（DTI）技术提供脑白质（WM） 在体内的微观过程的信息。本应用程序旨在探讨WM参与模式的差异，不同的脑部疾病，特别是神经退行性疾病，通过使用不同的DTI分析与匹配的对照比较。 DTI数据进行分析在变量的时尚，为了在集团层面， 即 voxelwise比较区域扩散方向的指标，如各向异性分数（FA），连同纤维跟踪（FT）陪同由的各向异性分数tractwise统计（TFAS）找出差异在FA随着WM结构，瞄准在组级别的WM改变区域格局的定义。改造成一个立体的标准空间组研究的前提条件是，需要彻底的数据处理到维护directional相互依存关系。本应用表明，优化的技术方法定向和定量的信息保存在集团层面在空间数据分析正常化。在此基础上，FT技术可以应用到组的场均数据，以量化指标信息，通过FT。此外，应用DTI方法， 即差异FA-映射后立体对齐，在个别科目进行纵向分析揭示神经系统疾病的进展信息。在预处理过程中应用受控消除高噪音水平的梯度方向，可以得到的DTI基于结果的质量进一步改善。 总之，DTI被用来定义一个独特的WM pathoanatomy的全脑和基于道DTI分析相结合的不同的脑疾病的。

1。质量控制和校正多动障碍的患者在应用程序的数据损坏的梯度方向由于的应用程序的质量控制和随后的体积排除（由于收到从而损坏的GD校正）的效果的一个例子， 图8显示了有和没有29亨廷顿premanifest的疾病组比较，体积排除的情况下在整个大脑基于空间统计信息的差异科目与30名年龄和性别匹配的对照。 1.5特斯拉MAGNETOM交响乐团（德国埃尔兰根西门子医疗）进?...

Watch this Scientific Journal Video about Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases at JoVE.com

Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases

弥散张量成像（DTI）基本上作为一个基于MRI的工具来识别<em&gt;在体内</em&gt;，大脑由于脑白质内神经系统疾病和病理过程中的微观结构。 DTI为基础的分析允许应用程序在组级和单一主体数据的脑部疾病。

磁共振扩散张量成像在神经退行性疾病的分析

Diffusion tensor imaging (DTI) techniques provide information on the microstructural processes of the cerebral white matter (WM) in vivo. The present ...

diffusion-tensor-magnetic-resonance-imaging-analysis

Research

JoVE Journal

Medicine

28.1K 次观看.  University of Ulm. 弥散张量成像（DTI）基本上作为一个基于MRI的工具来识别在体内，大脑由于脑白质内神经系统疾病和病理过程中的微观结构。 DTI为基础的分析允许应用程序在组级和单一主体数据的脑部疾病。

视频: Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.
Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.
Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.
Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.

An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF.

磁共振衍生的心肌劳损评估使用特征跟踪

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that ...

科研

医学

Probing the Brain in Autism Using fMRI and Diffusion Tensor Imaging

Newly emerging theories suggest that the brain does not function as a cohesive unit in autism, and this discordance is reflected in the behavioral symptoms displayed by individuals with autism. While structural neuroimaging findings have provided some insights into brain abnormalities in autism, the consistency of such findings is questionable. Functional neuroimaging, on the other hand, has been more fruitful in this regard because autism is a disorder of dynamic processing and allows examination of communication between cortical networks, which appears to be where the underlying problem occurs in autism. Functional connectivity is defined as the temporal correlation of spatially separate neurological events1. Findings from a number of recent fMRI studies have supported the idea that there is weaker coordination between different parts of the brain that should be working together to accomplish complex social or language problems2,3,4,5,6. One of the mysteries of autism is the coexistence of deficits in several domains along with relatively intact, sometimes enhanced, abilities. Such complex manifestation of autism calls for a global and comprehensive examination of the disorder at the neural level. A compelling recent account of the brain functioning in autism, the cortical underconnectivity theory,2,7 provides an integrating framework for the neurobiological bases of autism. The cortical underconnectivity theory of autism suggests that any language, social, or psychological function that is dependent on the integration of multiple brain regions is susceptible to disruption as the processing demand increases. In autism, the underfunctioning of integrative circuitry in the brain may cause widespread underconnectivity. In other words, people with autism may interpret information in a piecemeal fashion at the expense of the whole. Since cortical underconnectivity among brain regions, especially the frontal cortex and more posterior areas 3,6, has now been relatively well established, we can begin to further understand brain connectivity as a critical component of autism symptomatology.
A logical next step in this direction is to examine the anatomical connections that may mediate the functional connections mentioned above. Diffusion Tensor Imaging (DTI) is a relatively novel neuroimaging technique that helps probe the diffusion of water in the brain to infer the integrity of white matter fibers. In this technique, water diffusion in the brain is examined in several directions using diffusion gradients. While functional connectivity provides information about the synchronization of brain activation across different brain areas during a task or during rest, DTI helps in understanding the underlying axonal organization which may facilitate the cross-talk among brain areas. This paper will describe these techniques as valuable tools in understanding the brain in autism and the challenges involved in this line of research.

Neuroimaging techniques, such as functional MRI and Diffusion Tensor Imaging have become increasingly useful in characterizing the cognitive and neural deficits in autism. An examination of brain connectivity in autism at a network level along with adaptations for scanning children with developmental disabilities is presented.

探讨孤独症的脑功能磁共振成像和弥散张量成像

Newly emerging theories suggest that the brain does not function as a cohesive unit in autism, and this discordance is reflected in the behavioral ...

High Content Screening in Neurodegenerative Diseases

The functional annotation of genomes, construction of molecular networks and novel drug target identification, are important challenges that need to be addressed as a matter of great urgency1-4. Multiple complementary 'omics' approaches have provided clues as to the genetic risk factors and pathogenic mechanisms underlying numerous neurodegenerative diseases, but most findings still require functional validation5. For example, a recent genome wide association study for Parkinson's Disease (PD), identified many new loci as risk factors for the disease, but the underlying causative variant(s) or pathogenic mechanism is not known6, 7. As each associated region can contain several genes, the functional evaluation of each of the genes on phenotypes associated with the disease, using traditional cell biology techniques would take too long. 
	There is also a need to understand the molecular networks that link genetic mutations to the phenotypes they cause. It is expected that disease phenotypes are the result of multiple interactions that have been disrupted. Reconstruction of these networks using traditional molecular methods would be time consuming. Moreover, network predictions from independent studies of individual components, the reductionism approach, will probably underestimate the network complexity8. This underestimation could, in part, explain the low success rate of drug approval due to undesirable or toxic side effects. Gaining a network perspective of disease related pathways using HT/HC cellular screening approaches, and identifying key nodes within these pathways, could lead to the identification of targets that are more suited for therapeutic intervention.
	High-throughput screening (HTS) is an ideal methodology to address these issues9-12. but traditional methods were one dimensional whole-well cell assays, that used simplistic readouts for complex biological processes. They were unable to simultaneously quantify the many phenotypes observed in neurodegenerative diseases such as axonal transport deficits or alterations in morphology properties13, 14. This approach could not be used to investigate the dynamic nature of cellular processes or pathogenic events that occur in a subset of cells. To quantify such features one has to move to multi-dimensional phenotypes termed high-content screening (HCS)4, 15-17. HCS is the cell-based quantification of several processes simultaneously, which provides a more detailed representation of the cellular response to various perturbations compared to HTS. 
	HCS has many advantages over HTS18, 19, but conducting a high-throughput (HT)-high-content (HC) screen in neuronal models is problematic due to high cost, environmental variation and human error. In order to detect cellular responses on a 'phenomics' scale using HC imaging one has to reduce variation and error, while increasing sensitivity and reproducibility. 
	Herein we describe a method to accurately and reliably conduct shRNA screens using automated cell culturing20 and HC imaging in neuronal cellular models. We describe how we have used this methodology to identify modulators for one particular protein, DJ1, which when mutated causes autosomal recessive parkinsonism21. 
	Combining the versatility of HC imaging with HT methods, it is possible to accurately quantify a plethora of phenotypes. This could subsequently be utilized to advance our understanding of the genome, the pathways involved in disease pathogenesis as well as identify potential therapeutic targets.

We describe a methodology combining automated cell culturing with high-content imaging to visualize and quantify multiple cellular processes and structures, in a high-throughput manner. Such methods can aid in the further functional annotation of genomes as well as identify disease gene networks and potential drug targets.

在神经退行性疾病的高内涵筛选

The functional annotation of genomes, construction of molecular networks and novel drug target identification, are important challenges that need to be ...

The Use of Primary Human Fibroblasts for Monitoring Mitochondrial Phenotypes in the Field of Parkinson's Disease

Parkinson's disease (PD) is the second most common movement disorder and affects 1% of people over the age of 60 1. Because ageing is the most important risk factor, cases of PD will increase during the next decades 2. Next to pathological protein folding and impaired protein degradation pathways, alterations of mitochondrial function and morphology were pointed out as further hallmark of neurodegeneration in PD 3-11.
After years of research in murine and human cancer cells as in vitro models to dissect molecular pathways of Parkinsonism, the use of human fibroblasts from patients and appropriate controls as ex vivo models has become a valuable research tool, if potential caveats are considered. Other than immortalized, rather artificial cell models, primary fibroblasts from patients carrying disease-associated mutations apparently reflect important pathological features of the human disease.
Here we delineate the procedure of taking skin biopsies, culturing human fibroblasts and using detailed protocols for essential microscopic techniques to define mitochondrial phenotypes. These were used to investigate different features associated with PD that are relevant to mitochondrial function and dynamics. Ex vivo, mitochondria can be analyzed in terms of their function, morphology, colocalization with lysosomes (the organelles degrading dysfunctional mitochondria) and degradation via the lysosomal pathway. These phenotypes are highly relevant for the identification of early signs of PD and may precede clinical motor symptoms in human disease-gene carriers. Hence, the assays presented here can be utilized as valuable tools to identify pathological features of neurodegeneration and help to define new therapeutic strategies in PD.

The Use of Primary Human Fibroblasts for Monitoring Mitochondrial Phenotypes in the Field of Parkinson&#039;s Disease

Fibroblasts from patients carrying mutations in Parkinson's disease-causing genes represent an easily accessible ex vivo model to study disease-associated phenotypes. Live cell imaging gives the opportunity to study morphological and functional parameters in living cells. Here we describe the preparation of human fibroblasts and subsequent monitoring of mitochondrial phenotypes.

利用人类纤维原细胞线粒体表型的监测领域的帕金森氏病

Parkinson's disease (PD) is the second most  common movement disorder and affects 1% of people over the age of 60 1. Because ageing is  the most important ...

Tracking the Mammary Architectural Features and Detecting Breast Cancer with Magnetic Resonance Diffusion Tensor Imaging

Breast cancer is the most common cause of cancer among women worldwide. Early detection of breast cancer has a critical role in improving the quality of life and survival of breast cancer patients. In this paper a new approach for the detection of breast cancer is described, based on tracking the mammary architectural elements using diffusion tensor imaging (DTI). 
The paper focuses on the scanning protocols and image processing algorithms and software that were designed to fit the diffusion properties of the mammary fibroglandular tissue and its changes during malignant transformation. The final output yields pixel by pixel vector maps that track the architecture of the entire mammary ductal glandular trees and parametric maps of the diffusion tensor coefficients and anisotropy indices. 
The efficiency of the method to detect breast cancer was tested by scanning women volunteers including 68 patients with breast cancer confirmed by histopathology findings. Regions with cancer cells exhibited a marked reduction in the diffusion coefficients and in the maximal anisotropy index as compared to the normal breast tissue, providing an intrinsic contrast for delineating the boundaries of malignant growth. Overall, the sensitivity of the DTI parameters to detect breast cancer was found to be high, particularly in dense breasts, and comparable to the current standard breast MRI method that requires injection of a contrast agent. Thus, this method offers a completely non-invasive, safe and sensitive tool for breast cancer detection.

We describe how to obtain parametric and vector maps of the diffusion tensor of the breast using magnetic resonance imaging. The protocol and final output following imaging processing are tailored for tracking breast architectural features and detecting breast malignancy.

跟踪乳腺建筑特色与检测乳腺癌的磁共振扩散张量成像

Breast cancer is the most common cause of cancer among women worldwide. Early detection of breast cancer has a critical role in improving the quality of ...

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of living systems. Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using qMRI methods. The MRI acquisition protocol begins with localizer images (used to locate the position of the body and tissue of interest within the MRI system), quality control measurements of relevant magnetic field distributions, and structural imaging for general anatomical characterization. The qMRI portion of the protocol includes measurements of the longitudinal and transverse relaxation time constants (T1 and T2, respectively). Also acquired are diffusion-tensor MRI data, in which water diffusivity is measured and used to infer pathological processes such as edema. Quantitative magnetization transfer imaging is used to characterize the relative tissue content of macromolecular and free water protons. Lastly, fat-water MRI methods are used to characterize fibro-adipose tissue replacement of muscle. In addition to describing the data acquisition and analysis procedures, this paper also discusses the potential problems associated with these methods, the analysis and interpretation of the data, MRI safety, and strategies for artifact reduction and protocol optimization.

Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using non-invasive magnetic resonance imaging methods.

骨骼肌疾病的定量磁共振成像

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of ...

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics disturbance in affected cells. Diffusion weighted magnetic resonance imaging (MRI) identifies regions that are damaged, potentially irreversibly, by hypoxia-ischemia. Alterations in glucose utilization in the affected tissue may be detectable by positron emission tomography (PET) imaging of 2-deoxy-2-(18F)fluoro-&#7429;-glucose ([18F]FDG) uptake. Due to the rapid and variable nature of injury in this animal model, acquisition of both modes of data must be performed simultaneously in order to meaningfully correlate PET and MRI data. In addition, inter-animal variability in the hypoxic-ischemic injury due to vascular differences limits the ability to analyze multi-modal data and observe changes to a group-wise approach if data is not acquired simultaneously in individual subjects. The method presented here allows one to acquire both diffusion-weighted MRI and [18F]FDG uptake data in the same animal before, during, and after the hypoxic challenge in order to interrogate immediate physiological changes.

The method presented here uses simultaneous positron emission tomography and magnetic resonance imaging. In the cerebral hypoxia-ischemia model, dynamic changes in diffusion and glucose metabolism occur during and after injury. The evolving and irreproducible damage in this model necessitates simultaneous acquisition if meaningful multi-modal imaging data are to be acquired.

同时PET / MRI成像在小鼠脑缺氧缺血

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics ...

Cardiac Magnetic Resonance Imaging at 7 Tesla

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher magnetic field strengths and potentially provides improved signal contrast and spatial resolution. While promising results have been achieved, ultra-high field CMR is challenging due to energy deposition constraints and physical phenomena such as transmission field non-uniformities and magnetic field inhomogeneities. In addition, the magneto-hydrodynamic effect renders the synchronization of the data acquisition with the cardiac motion difficult. The challenges are currently addressed by explorations into novel magnetic resonance technology. If all impediments can be overcome, ultra-high field CMR may generate new opportunities for functional CMR, myocardial tissue characterization, microstructure imaging or metabolic imaging. Recognizing this potential, we show that multi-channel radio frequency (RF) coil technology tailored for CMR at 7 Tesla together with higher order B0 shimming and a backup signal for cardiac triggering facilitates high fidelity functional CMR. With the proposed setup, cardiac chamber quantification can be accomplished in examination times similar to those achieved at lower field strengths. To share this experience and to support the dissemination of this expertise, this work describes our setup and protocol tailored for functional CMR at 7 Tesla.

The sensitivity gain inherent to ultrahigh field magnetic resonance holds promise for high spatial resolution imaging of the heart. Here, we describe a protocol customized for functional cardiovascular magnetic resonance (CMR) at 7 Tesla using an advanced multi-channel radio-frequency coil, magnetic field shimming and a triggering concept.

7号特斯拉的心脏磁共振成像

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher ...

Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery

Phase contrast magnetic resonance imaging (PC-MRI) is a noninvasive approach that can quantify flow-related parameters such as blood flow. Previous studies have shown that abnormal blood flow may be associated with systemic vascular risk. Thus, PC-MRI can facilitate the translation of data obtained from animal models of cardiovascular diseases to pertinent clinical investigations. In this report, we describe the procedure for measuring blood flow in the common carotid artery (CCA) of rats using cine-gated PC-MRI and discuss relevant analysis methods. This procedure can be performed in a live, anesthetized animal and does not require euthanasia after the procedure. The proposed scanning parameters yield repeatable measurements for blood flow, indicating excellent reproducibility of the results. The PC-MRI procedure described in this article can be used for pharmacological testing, pathophysiological assessment, and cerebral hemodynamics evaluation.

The overall goal of this procedure is to measure the blood flow in the rat common carotid artery by using noninvasive phase contrast magnetic resonance imaging.

大鼠颈总动脉的相位对比磁共振成像

Phase contrast magnetic resonance imaging (PC-MRI) is a noninvasive approach that can quantify flow-related parameters such as blood flow. Previous ...

Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The appearance of a mass on certain magnetic resonance (MR) sequences can help differentiate a thrombus from competing diagnoses such as a tumor. T1 and T2 signal characteristics of a thrombus are related to the evolution of hemoglobin properties. A thrombus typically does not enhance following contrast administration, which also helps differentiation from a tumor. We also highlight the emerging role of T1 mapping in the evaluation of a thrombus, which can add another level of support in diagnosis. Prior to any CMR exam, patient screening and interviews are critical to ensure safety and to optimize patient comfort. Effective communication during the exam between the technologist and the patient promotes proper breath holding technique and higher quality images. Volumetric post processing and structured reporting are helpful to ensure that the radiologist answers the ordering services&#39; question and communicates these results effectively. Optimal pre-MR safety evaluation, CMR exam execution, and post exam processing and reporting allow for delivery of high quality radiological service in the evaluation of a suspected cardiac thrombus.

The goal of this article is to describe how cardiac magnetic resonance can be used for the evaluation and diagnosis of a suspected cardiac thrombus. The method presented will describe data acquisition as well as the pre-procedure and post-procedure protocol.

心脏磁共振评估疑似心脏血栓:常规和新兴技术

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The ...