1。简介边界的自动检测图像分析中的一个根本问题。在心脏成像，成像左心室心内膜边界的自动检测的可能性将给予客观测量的心室卷，心肌变形（应变）。这是在超声心动图斑点追踪技术完成。可靠的自动边界检测方法的发展，是一项艰巨的任务，并没有收到普遍可靠的解决方案，在心脏磁共振（CMR）的。事实上，在临床实践中，边框是绘制手动操作员或软件检测到心肌和腔1,2之间的接口。在当前文章中，我们引入了不同的方法，边界不“检测”，而他们是“跟踪”，即遵循时间，从一个可靠的现有瞬时跟踪，是通常，但不一定由有经验的操作手动绘制起点超过一个单一的框架。其次在时间上的个别点组成这样的第一个可靠的跟踪搜索相同的功能，在其附近的一个点在下面的帧。跟踪功能，可以腔组织边界或解剖的元素，沿不同的组织。他们发现，在两个地区的两帧之间的利益的最大似然方法。 本地帧到帧的位移相当于评估当地的速度（位移和时间间隔之间的比例）。在一个点的速度自动评价是从比较这样的点在两个连续帧图像数据的位移决定。已使用这种方法，在几个不同的配方，在许多研究领域。他们属于普通类被称为光流，在先进的图像分析3,4。它们通常被称为斑点跟踪回波仪成像时使用这样的速度是遵循生理的议案5，6，但也适用于任何如CMR其他图像模式，这些方法都提到功能跟踪或边境跟踪。 2。材料和方法特征跟踪方法心内膜或心外膜的边界是一个2D的CMR电影手动追溯到一个任意帧（见图1）。以及可以追溯到中秋节心肌功能。这种边界被定义为一个N点的序列，鉴定，由他们协调对的（X I，Y I）I = 1，... ，N。边界跟踪，通过跟踪每个单点的收益，这种跟踪是基于一个层次多尺度算法和1D跟踪技术的结合，从而保证更高的精度，和二维跟踪，这是必要的，正确地检测到的二维空间扩展功能。 为了第一次捕捉边界的几何大位移，跟踪的方向正交边界本身腔组织的边界是最好辨认的。沿着这个方向进行跟踪，使用的方法如下（见图3）透削减。绘制一条线，穿过隔离墙，通过点和正交。沿透行所采取的像素被放置在列，每列对应一个图像序列帧。沿切透的演变，可以通过这种方式为代表的一次在一个二维的代表性，其中一轴是沿直线的距离和其他轴是时间（见图2）所有的瞬间。这种表示是被称为一个M -模式在超声心动图中的CMR，它对应的“侦察兵”功能相似。为了提高分析的质量，在低信噪比图像不佳的情况下，，空间时间的表示是建行透削减为5个像素的厚度。边界跟踪，然后沿着时空的形象。 边界的二维位移，一个标准的2D跟踪（基于光流）在第二个步骤是，每个点独立，在MXM移动窗口总是在以前估计的边界点为中心。二维跟踪两个步骤进行，第一次估计有一半是受雇于第二个跟踪通道中心的移动窗口。窗口，然后从32减少到16个，在另外两个通道。 为了提高精度沿用来估计旋转和扭转的边界的议案，1D跟踪沿着从“水货”的弧形边界（见图3）厚削减内置的时空图像。 ，独立，在每个点的像素采取移动边界沿线，在移动边界点为中心，是摆在列，每列对应一帧图像序列。为了提高分析的质量，最好的捕捉功能，在边境线是5个像素延伸到组织（亚心内膜）。边界跟踪，然后沿着时空的形象与上述相同的步骤进行。为了确保在跟踪边界的空间相干性，3点的中值滤波和3点高斯滤波器（权重0.25，0.5，0.25）是适用于在邻近点在每一步计算的位移。 沿着二维时空图像追踪本节介绍了一个过程，在二维图像从一个众所周知的立场，在一个瞬间（M型状）一个边界沿着一个方向。 X是定义的水平方向和Y垂直方向。列注明X I，I = 1 ... M，其中M是图像中的列的数量。跟踪是一个实数Y I = Y（X）的离散序列的测定，从一个已知点相应的列x k Y K开始。 从已知点Y K K +1 点的Y位移估计评估之间在 x k在 x k +1的整列整列的交叉相关。互相关函数将目前最大，最高的位置给需要两列之间的相似性最大化的垂直位移值 ，因此Y K +1估计，加入这样的位移为y k。重复此过程和附近的列所有对之间的结果是整个边境的估计 Y I，I = 1 ... M.在这里交叉相关计算使用快速傅立叶变换算法，以减少计算时间。 先估计Y I的进一步细化迭代。为了实现这一目标的图像的一个子集提取，通过采取以上和低于以前的估计Y I和一个新的形象，其中心对应的序列y我是生成的，用于校正跟踪几点。这一修改是反复，直到找到不改正的。 改进和更自然的结果，然后由最后的蛇过程[5]实现按照时空的形象，图像的亮度水平， 通过定点 Y K。整个过程使用的时间周期，以确保一个周期性的结果，避免漂移的影响。 特征跟踪技术的限制边界跟踪技术，像任何斑点追踪的方法，是基于像素的亮度变化进行量化，从一帧到其他。这给出了一个下限需要看到一个斑点，是在一帧的一个像素，移动到相邻的像素在下一帧的速度有关。因此，此限制 <img src="/files/ftp_upload/2356/2356eq1.jpg" alt="公式1" /> 公式1 其中Δx是像素的大小和Δt是两帧之间的时间间隔。系数K取决于跟踪算法的质量和能力评估动态子像素的变化。此限制意味着速度远高于此限制是非常准确的估计，这样的精度降低速度值的方法时，低于限额。 这种限制也意味着，在收购一方的帧速率（ΔT减少）增加允许一个大的速度和他们的快速变化（如在等容相）更容易评估。在另一边，帧速率（ΔT减少）增加增加此限制，意味着在速度较低的评价的精度降低，直到它不伴随着类似的空间分辨率的增加（减少Δx的）。 幻影形象准备一系列人工计算机生成的循环已经准备允许在图像分析过程简单，完全控制的条件下的测试。为此，在一个理想的左心室短轴投影的幻影如下准备。 心内膜和心外膜边界表示半径为R 0（T）和 R（T），分别由两个同心圆。形象准备的纤维环，其中代表中TS两国边界的组织，统一颜色的黑色背景上的灰色。然后，一个8x8顶帽子线性滤波器应用，以避免非物理的不连续性。 心外膜运动是采取以[mm]，为 R 0（T）= 10 +5 COS（2πt/吨），其中 T是心跳期为 T = 1秒 。理论内膜运动是恒定的边界沿线取决于时间，速度只有径向和V0（T）= DR 的0 / dt =-π罪（2πt/吨），厘米/秒。百分比应变，计算相对长的边界，在零时间， 是ST 0（T）= 100X（R 0（T）- R 0（0））/ 0（0）= 100（COS（2πt/ T ）-1）/ 3，和应变率如下（1）SR 0（T）= 10 V0 / R 0，在[S -1]。心外膜被假定为移动相应的厚度不变，R 1（T）= R 0（T）五毫米 ，或R 1（T）= R 0（0）5毫米 。 每幅图像大小48毫米，为本组织环广场，和一项决议NxN的。例如图像，如图4所示，板A和B的应变和应变率时间曲线显示在图4中，板C和D准备通过不同的分辨率氮，帧速率FR，和心外膜的运动型循环。 心内膜的跟踪方法应用到的图像，在第一帧上均匀地沿着圆形内膜间隔一个数N点P。 3。代表性的成果幻影研究幻象计算机生成的图像的图像分析方法的应用是在这里进行了分析。计算最终错误的一个全球性的措施是由根均方的百分比差异。平均内膜应变平方米，平均和最大的错误被定义为根 <img src="/files/ftp_upload/2356/2356eq2.jpg" alt="公式（2）" /> 公式（2） ST 0（T）的精确值，ST（T）是由图像分析计算值，并求和的所有帧延长N F = FRxT。使用相同的定义是为半径，速度和应变率。跟踪沿心内膜的位置大约是独立的，不同点之间的差异，远低于1％。 结果表一归纳为15个不同空间分辨率的幽灵，帧速率，并外膜边界的运动类型;用来跟踪的心内膜边界点的数目不同的效果也是所示。 在所有情况下，错误非常小的不可分割的数量（半径和应变）和差量（速度和应变率）都涉及到前衍生略大一些。这是预料中的，因为衍生运营商放大错误。结果的质量是退化的分辨率降低时，事实上，相关的像素大小代表（在一个松散的意义）从一帧到其他可读的最小排量的准确性。时间分辨率不显着影响的结果，直到足够的帧速率非常高帧速率的结果，不改善，因为帧帧位移低于像素大小。这表明，帧速率增加时，它不是由伴随着在空间分辨率的增加很少或根本没有效用。 然而，简单的正弦运动，在这里考虑，并不需要一个极端的时间分辨率。同样，使用尽可能少的8点就足够了，按照简单，圆形，心内膜形状。内膜的结果没有明显影响运动型外膜经历。我们也验证的结果是没有显着影响所采用的图像滤波。 图4中的视觉呈现的结果是计算两个瞬间的心内膜边界是在幻影图像（板A和B）的报告。 （板，C和D）的情况下，＃1和＃8小分辨率的情况下，应变和应变率的报道。应变和应变率＃1（正方形）的情况下提出与理论值，平均误差分别为0.6％和3％，等于一个很好的协议。该协议是只有一点点的情况下＃8，图像分辨率减半，有错误的应变和应变率的0.9％和4.5％，分别差。 临床验证1。 我们比较中旬LV全片圆周谐波相位成像（竖琴）和FT技术心肌劳损191 Duchene肌肉萎缩症patie（εCC）NTS按年龄和心功能不全的严重程度和42岁的匹配，控制科目。匹配的标签和SSFP片回顾展，离线分析。对于整个研究人群（N = 233），意味着金融时报εCC（-13.3 ± 3.8％），高度相关哈弗εCC（-13.6 ± 3.4％）与Pearson相关系数为0.899 。由哈弗（-12.52 ± 2.69％）和FT确定的DMD患者平均εCC（-12.16 ± 3.12％）均无显着差异（P = NS） 。同样，确定哈弗（-18.85 ± 1.86）和FT（-18.81 ± 1.83），对照组的平均εCC无显着差异（P = NS） 。我们得出的结论是基于FT -εCC评估与标签在一个大的DMD患者的心功能不全的广泛人口的图像所得 εCC高度。 <table border="1"><tbody><tr><td>幻影＃ </td><td>帧速率</td><td> Resol，N </td><td>心外膜的议案</td><td> N P </td><td> εř </td><td> εr 最高 </td><td> εV </td><td> εV 最大 </td><td> ε 简 </td><td> εSR 最大 </td><td> ε 圣 </td><td> ε 圣 最大 </td></tr><tr><td> 1 </td><td> 32 </td><td> 401 </td><td>与远藤</td><td> 16 </td><td> 0.57 </td><td> 1.10 </td><td> 3.98 </td><td> 8.26 </td><td> 2.95 </td><td> 6.55 </td><td> 0.59 </td><td> 1.34 </td></tr><tr><td> 2 </td><td> 32 </td><td> 401 </td><td> 没有运动 </td><td> 16 </td><td> 0.27 </td><td> 0.60 </td><td> 3.62 </td><td> 8.53 </td><td> 2.90 </td><td> 5.99 </td><td> 0.75 </td><td> 1.29 </td></tr><tr><td> 3 </td><td> 64 </td><td> 401 </td><td>与远藤</td><td> 16 </td><td> 0.35 </td><td> 0.62 </td><td> 1.75 </td><td> 4.92 </td><td> 3.08 </td><td> 10.47 </td><td> 0.34 </td><td> 0.86 </td></tr><tr><td> 4 </td><td> 64 </td><td> 401 </td><td> 没有运动 </td><td> 16 </td><td> 0.39 </td><td> 0.73 </td><td> 1.78 </td><td> 5.48 </td><td> 2.38 </td><td> 6.46 </td><td> 0.32 </td><td> 0.63 </td></tr><tr><td> 5 </td><td> 128 </td><td> 401 </td><td>与远藤</td><td> 16 </td><td> 0.22 </td><td> 0.40 </td><td> 1.57 </td><td> 3.66 </td><td> 2.73 </td><td> 8.39 </td><td> 0.35 </td><td> 0.89 </td></tr><tr><td> 6 </td><td> 16 </td><td> 401 </td><td>与远藤</td><td> 16 </td><td> 0.41 </td><td> 0.92 </td><td> 12.10 </td><td> 18.27 </td><td> 7.12 </td><td> 15.17 </td><td> 0.88 </td><td> 1.93 </td></tr><tr><td> 7 </td><td> 32 </td><td> 201 </td><td>与远藤</td><td> 16 </td><td> 0.43 </td><td> 0.82 </td><td> 3.84 </td><td> 7.03 </td><td> 4.21 </td><td> 7.79 </td><td> 0.83 </td><td> 1.52 </td></tr><tr><td> 8 </td><td> 32 </td><td> 201 </td><td> 没有运动 </td><td> 16 </td><td> 0.49 </td><td> 0.90 </td><td> 4.00 </td><td> 8.54 </td><td> 4.54 </td><td> 10.84 </td><td> 0.93 </td><td> 1.64 </td></tr><tr><td> 9 </td><td> 32 </td><td> 101 </td><td>与远藤</td><td> 16 </td><td> 2.58 </td><td> 3.87 </td><td> 5.70 </td><td> 17.44 </td><td> 9.22 </td><td> 18.27 </td><td> 4.44 </td><td> 6.77 </td></tr><tr><td> 10 </td><td> 32 </td><td> 401 </td><td>与远藤</td><td> 64 </td><td> 0.32 </td><td> 0.73 </td><td> 3.98 </td><td> 8.09 </td><td> 3.11 </td><td> 8.86 </td><td> 0.48 </td><td> 1.10 </td></tr><tr><td> 11 </td><td> 32 </td><td> 401 </td><td> 没有运动 </td><td> 64 </td><td> 0.33 </td><td> 0.53 </td><td> 3.56 </td><td> 7.83 </td><td> 2.78 </td><td> 7.44 </td><td> 0.70 </td><td> 0.98 </td></tr><tr><td> 12 </td><td> 32 </td><td> 401 </td><td>与远藤</td><td> 32 </td><td> 0.44 </td><td> 1.00 </td><td> 3.99 </td><td> 8.16 </td><td> 2.99 </td><td> 6.82 </td><td> 0.63 </td><td> 1.49 </td></tr><tr><td> 13 </td><td> 32 </td><td> 401 </td><td>与远藤</td><td> 8 </td><td> 0.20 </td><td> 0.41 </td><td> 3.64 </td><td> 6.84 </td><td> 3.09 </td><td> 9.10 </td><td> 0.43 </td><td> 0.74 </td></tr><tr><td> 14 </td><td> 32 </td><td> 401 </td><td> 没有运动 </td><td> 8 </td><td> 0.22 </td><td> 0.41 </td><td> 3.36 </td><td> 7.42 </td><td> 2.76 </td><td> 5.93 </td><td> 0.58 </td><td> 1.01 </td></tr><tr><td> 15 * </td><td> 32 </td><td> 401 </td><td>与远藤</td><td> 16 </td><td> 1.35 </td><td> 2.42 </td><td> 5.54 </td><td> 9.68 </td><td> 7.02 </td><td> 16.58 </td><td> 2.62 </td><td> 4.46 </td></tr></tbody></table> 表1：魅影心内膜边界跟踪分析：根均方和最大percentual的错误[％]为在不同的幻象参数对应的主要数量计算。参数标记大胆表明幻影＃1的变化。被认为是帧速率，分辨率和跟踪点的数量的依赖。心外膜运动类型的影响，被认为是两个极限情况时心外膜的边界不动（运动）或远藤（没有增厚）的动议。最后的幻象（*）是建立无滤波，带亮度突然改变一个像素的基本逐步图像。 10％以上的错误标记为粗体。 <img src="/files/ftp_upload/2356/2356fig1.jpg" alt="图1" /> 图1。CMR图像的左心室长轴（左图）和短轴（右图）与追踪的心内膜边界，绘制上顶部。 <img src="/files/ftp_upload/2356/2356fig2.jpg" alt="图2" /> 图2。时空的代表性，在空间的图像序列，沿切透。透削减为出发点，在图3。时间演化的出发点，自动跟踪，报道。 <img src="/files/ftp_upload/2356/2356fig3.jpg" alt="图3" /> 图3。左心室，透裁员和削减弧形边界平行，长轴图像。 <img src="/files/ftp_upload/2356/2356fig4.jpg" alt="图4" /> 图4。幻影研究。两幅图像（＃2的情况下）最大扩展（板）和收缩（板B），计算心内膜边界点是重叠的。应变（板C）和应变率（板D）计算实际值的比较显示两个不同的幽灵（例＃1和＃8）。 <img src="/files/ftp_upload/2356/2356fig5.jpg" alt="图5" /> 图5（一）全球圆周（黑色曲线）和节段性应变正常患者（彩色曲线）的例子。全球圆周（黑色曲线）和节段性circumferental starain郁闷的左心室功能和左束支传导阻滞（二）患者（彩色曲线）的例子。请注意不同的计时显示左室不同步的存在峰值圆周应变

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	<li>Hor, K. N., Gottliebson, W. M., Carson, C., Wash, E., Cnota, J., Fleck, R., Wansapura, J., Klimeczek, P., Al-Khalidi, H. R., Chung, E. S., Benson, D. W., Mazur, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+Resonance+Feature+Tracking:+Comparison+of+Feature+Tracking+Method+for+Strain+Calculation+with+Harmonic+Phase+Imaging+Analysis+.">Magnetic Resonance Feature Tracking: Comparison of Feature Tracking Method for Strain Calculation with Harmonic Phase Imaging Analysis .</a> JACC Cardiovasc Imaging. 3 (2), 152-154 (2010).</li><li>Maret, E., Todt, T., Brudin, L., Nylander, E., Swahn, E., Ohlsson, J. L., Engvall, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+measurement+based+on+feature+tracking+of+cine+magnetic+resonance+images+identify+left+ventricular+segments+with+myocardial+scar.">Functional measurement based on feature tracking of cine magnetic resonance images identify left ventricular segments with myocardial scar.</a> Cardiovascular Ultrasound. 7, 53-53 (2009).</li><li>Singh, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Optic Flow Computation: A Unified Perspective. , (1992).</li><li>Barron, J. L., Fleet, D. J., Beauchemin, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+of+optical+flow+techniques.">Performance of optical flow techniques.</a> International Journal of Computer Vision. 12, 43-77 (1994).</li><li>Bohs, L. N., Geiman, B. J., Anderson, M. E., Gebhart, S. C., Trahey, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Speckle+tracking+for+multi-dimensional+flow+estimation.">Speckle tracking for multi-dimensional flow estimation.</a> Ultrasonics. 38, 369-375 (2000).</li><li>Malpica, N., Santos, A., Zuluaga, M. A., Ledesma, M. J., P&#233;rez, E., Garcia-Fernandez, M. A., Desco, M., M, . <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracking+of+Regions-of-Interest+in+myocardial+contrast+echocardiography.">Tracking of Regions-of-Interest in myocardial contrast echocardiography.</a> Ultrasound in Med. &#38; Biol. 30, 303-309 (2004).</li></ol>

罗尔夫鲍曼是TomTec成像系统公司，德国的雇员

我们描述了一种新方法“功能跟踪”来衡量SSFP图像所得的心肌组织中的变形和位移参数。这种方法最近被确认对全球高峰在一个人口众多的杜氏肌营养不良症（1）患者的周向应变的评估竖琴。我们发现这两种技术之间的一个极好的相关性。特征跟踪技术是在使用相对简单，不需要任何额外的成像序列，如标记，检测或密集。此外临床验证峰值全球ECC的评估，区域应变数据可以得出，以及金融时报“似乎是一个强大的技术能够估计的纵向和径向的LV的应变以及纵向右心室应变。 为了准确地确定有关时间和空间分辨率的图像技术的限制，需要进行更多的研究。 FT允许跨其他方式，如超声心动图的比较，因为其基本原理是相同的。 结论特征跟踪已在临床实践中，因为它省去了耗时的分析和额外的采集程序需要集成的潜力。 FT可用于评估的左，右心室全球和节段性株，左室不同步。正在进行进一步的临床研究，以评估临床心脏病学的FT有用。

A correction was made to <a href="http://www.jove.com/video/2356">Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking</a>. An author's given name was updated.
The author's name was updated from:
Woodrow Benson
to:
D. Woodrow Benson

A correction was made to <a href="http://www.jove.com/video/2356">Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking</a>. An author's given name was updated.

Erratum: Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

<ul><li>第欧根尼®特征跟踪软件（TomTec成像系统，德国富尔达，） </li></ul>

magnetic resonance derived myocardial strain assessment using feature tracking

目的：准确和实用的方法来衡量心肌组织应变等参数，是很大的临床价值，因为它已被证明，这株是收缩功能障碍的更为敏感，早于经常使用的参数EF标记。当前的CMR技术费时，而且难以在临床实践中实施。特征跟踪是一种技术，可以导致比比较的方法用更少的时间消耗更多automization和定量分析的医学图像的鲁棒性。 方法：在单相自动或手动输入初始化从该系统开始追踪个别图案代表解剖结构，随着时间的推移的位移。这种方法的专业是不需要任何类似CMR的图像，例如标记的方式，事先操纵图像。 结果：该方法很好地适合跟踪肌肉组织和心肌和定量阐述这使血流量。 结论：这种新方法提供了一个强大的和节省时间的程序，定期对CMR成像序列的位移，速度和变形参数量化心肌组织和血液。因此，它可以在临床实践中实施。

Watch this Scientific Journal Video about Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking at JoVE.com

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

准确和实用的方法来衡量心肌组织应变等参数，具有很大的临床价值，因为它已被证明，这株是收缩功能障碍的更为敏感，早于经常使用的参数EF标记。

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 ...

magnetic-resonance-derived-myocardial-strain-assessment-using-feature

Research

JoVE Journal

Medicine

14.2K 次观看.  Cincinnati Children Hospital Medical Center (CCHMC). 准确和实用的方法来衡量心肌组织应变等参数，具有很大的临床价值，因为它已被证明，这株是收缩功能障碍的更为敏感，早于经常使用的参数EF标记。

视频: Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling

This demonstrates a MR imaging method to measure the spatial distribution of pulmonary blood flow in healthy subjects 
during normoxia (inspired O2, fraction (FIO2) = 0.21) hypoxia (FIO2 = 0.125), and hyperoxia 
(FIO2 = 1.00). In addition, the physiological responses of the subject are monitored in the MR scan environment. MR images 
were obtained on a 1.5 T GE MRI scanner during a breath hold from a sagittal slice in the right lung at functional residual capacity. An arterial 
spin labeling sequence (ASL-FAIRER) was used to measure the spatial distribution of pulmonary blood flow 1,2 and a multi-echo fast 
gradient echo (mGRE) sequence 3 was used to quantify the regional proton (i.e. H2O) density, allowing the quantification 
of density-normalized perfusion for each voxel (milliliters blood per minute per gram lung tissue). 
With a pneumatic switching valve and facemask equipped with a 2-way non-rebreathing valve, different oxygen concentrations 
were introduced to the subject in the MR scanner through the inspired gas tubing. A metabolic cart collected expiratory gas via expiratory tubing. Mixed expiratory O2 and CO2 concentrations, oxygen consumption, carbon dioxide production, respiratory exchange ratio, 
respiratory frequency and tidal volume were measured. Heart rate and oxygen saturation were monitored using pulse-oximetry. 
Data obtained from a normal subject showed that, as expected, heart rate was higher in hypoxia (60 bpm) than during normoxia (51) or hyperoxia (50) and the arterial oxygen saturation (SpO2) was reduced during hypoxia to 86%. Mean ventilation was 8.31 L/min BTPS during hypoxia, 7.04 L/min during normoxia, and 6.64 L/min during hyperoxia. Tidal volume was 0.76 L during hypoxia, 0.69 L during normoxia, and 0.67 L during hyperoxia. 
Representative quantified ASL data showed that the mean density normalized perfusion was 8.86 ml/min/g during hypoxia, 8.26 ml/min/g during normoxia and 8.46 ml/min/g during hyperoxia, respectively. In this subject, the relative dispersion4, an index of global heterogeneity, was increased in hypoxia (1.07 during hypoxia, 0.85 during normoxia, and 0.87 during hyperoxia) while the fractal dimension (Ds), another index of heterogeneity reflecting vascular branching structure, was unchanged (1.24 during hypoxia, 1.26 during normoxia, and 1.26 during hyperoxia). 
Overview. This protocol will demonstrate the acquisition of data to measure the distribution of pulmonary perfusion noninvasively under conditions of normoxia, hypoxia, and hyperoxia using a magnetic resonance imaging technique known as arterial spin labeling (ASL). 
Rationale: Measurement of pulmonary blood flow and lung proton density using MR technique offers high spatial resolution images which can be quantified and the ability to perform repeated measurements under several different physiological conditions. In human studies, PET, SPECT, and CT are commonly used as the alternative techniques. However, these techniques involve exposure to ionizing radiation, and thus are not suitable for repeated measurements in human subjects.

A MR imaging method to study the distribution of pulmonary blood flow under a variety of physiological conditions, in this case exposure to three different inspired oxygen concentrations: hypoxia, normoxia, and hyperoxia, is described. This technique utilizes human pulmonary physiology research techniques in an MR scanning environment.

使用校准动脉自旋标记磁共振肺灌注显像定量

This demonstrates a MR imaging method to measure the spatial distribution of pulmonary blood flow in healthy subjects 
during normoxia (inspired O2, ...

科研

医学

Ultrasonic Assessment of Myocardial Microstructure

Echocardiography is a widely accessible imaging modality that is commonly used to noninvasively characterize and quantify changes in cardiac structure and function. Ultrasonic assessments of cardiac tissue can include analyses of backscatter signal intensity within a given region of interest. Previously established techniques have relied predominantly on the integrated or mean value of backscatter signal intensities, which may be susceptible to variability from aliased data from low frame rates and time delays for algorithms based on cyclic variation. Herein, we describe an ultrasound-based imaging algorithm that extends from previous methods, can be applied to a single image frame&#160;and accounts for the full distribution of signal intensity values derived from a given myocardial sample. When applied to representative mouse and human imaging data, the algorithm distinguishes between subjects with and without exposure to chronic afterload resistance. The algorithm offers an enhanced surrogate measure of myocardial microstructure and can be performed using open-access image analysis software.

Echocardiography is commonly used to noninvasively characterize and quantify changes in cardiac structure and function. We describe an ultrasound-based imaging algorithm that offers an enhanced surrogate measure of myocardial microstructure and can be performed using open-access image analysis software.

心肌微观结构超声波评估

Echocardiography is a widely accessible imaging modality that is commonly used to noninvasively characterize and quantify changes in cardiac structure and ...

Myocardial Infarction and Functional Outcome Assessment in Pigs

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One important prerequisite is a good understanding of all safety and efficacy aspects obtained in a large animal model that validly reflect the human scenario of myocardial infarction (MI). Pigs are widely used in this regard since their cardiac size, hemodynamics, and coronary anatomy are close to that of humans. Here, we present an effective protocol for using the porcine MI model using a closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. This approach is based on 90 min of myocardial ischemia, inducing large left ventricle infarction of the anterior, septal and inferoseptal walls. Furthermore, we present protocols for various measures of outcome that provide a wide range of information on the heart, such as cardiac systolic and diastolic function, hemodynamics, coronary flow velocity, microvascular resistance, and infarct size. This protocol can be easily tailored to meet study specific requirements for the validation of novel cardioregenerative biologics at different stages (i.e. directly after the acute ischemic insult, in the subacute setting or even in the chronic MI once scar formation has been completed). This model therefore provides a useful translational tool to study MI, subsequent adverse remodeling, and the potential of novel cardioregenerative agents.

This protocol describes the porcine myocardial infarction (MI) model using a 90 min closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. Furthermore, the protocol for several outcome parameters, such as cardiac function, hemodynamics, microvascular resistance, and infarct size, are also presented.

心肌梗死和功能预后评估的猪

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One ...

Noninvasive Assessment of Cardiac Abnormalities in Experimental Autoimmune Myocarditis by Magnetic Resonance Microscopy Imaging in the Mouse

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-&#945; 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-&#945; 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies.

This study demonstrates the successful establishment of magnetic resonance microscopy imaging as a non-invasive tool to assess the cardiac abnormalities in mice affected with autoimmune myocarditis. The data indicate that the technique can be used to monitor the disease-progression in live animals.

心脏异常的实验性自身免疫性心肌炎的无创性评估磁共振成像显微镜在鼠标

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events ...

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 ...

Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are therefore required to confine cardiac damage, promote survival and reduce the disease burden of heart failure. Large animal experiments are an essential part in the translational process from experimental to clinical therapies. To optimize clinical translation, robust and representative outcome measures are mandatory. The present manuscript aims to address this need by describing the assessment of three clinically relevant outcome modalities in a pig acute myocardial infarction (AMI) model: infarct size in relation to area at risk (IS/AAR) staining, 3-dimensional transesophageal echocardiography (TEE) and admittance-based pressure-volume (PV) loops. Infarct size is the main determinant driving the transition from AMI to heart failure and can be quantified by IS/AAR staining. Echocardiography is a reliable and robust tool in the assessment of global and regional cardiac function in clinical cardiology. Here, a method for three-dimensional transesophageal echocardiography (3D-TEE) in pigs is provided. Extensive insight into cardiac performance can be obtained by admittance-based pressure-volume (PV) loops, including intrinsic parameters of myocardial function that are pre- and afterload independent. Combined with a clinically feasible experimental study protocol, these outcome measures provide researchers with essential information to determine whether novel therapeutic strategies could yield promising targets for future testing in clinical studies.

Reliable and accurate outcome assessment is the key for translation of preclinical therapies into clinical treatment. The current paper describes how to assess three clinically relevant primary outcome parameters of cardiac performance and damage in a pig acute myocardial infarction model.

急性心肌梗死的猪模型主要成果评估

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are ...

Transthoracic Speckle Tracking Echocardiography for the Quantitative Assessment of Left Ventricular Myocardial Deformation

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the examiners&#39; expertise. Speckle tracking Echocardiography (STE) is a promising but technically challenging method that can be used to quantitatively assess regional and global systolic and diastolic myocardial performance. Myocardial strain and strain rate can be measured in all three dimensions&#160;&#8212; radial, circumferential, longitudinal &#8212; of myocardial deformation. Standard cross-sectional two-dimensional B-mode images are recorded and subsequently postprocessed by automated continuous frame-by-frame tracking and motion analysis of speckles within the myocardium. Images are recorded as digital loops and synchronized to a 3-lead EKG for timing purposes. Longitudinal deformation is assessed in the apical 4-, 3-, and 2-chamber views. Circumferential and radial deformation are measured in the parasternal short axis plane.
Optimal image quality and accurate tissue tracking are paramount for the correct determination of myocardial performance parameters. Utilizing transthoracic STE in a healthy volunteer, the present article is a detailed outline of the essential steps and potential pitfalls of quantitative echocardiographic myocardial deformation analysis.

Speckle tracking echocardiography is an emerging diagnostic imaging technique for the quantitative assessment of global and regional myocardial performance. Standard view echocardiographic motion images are recorded and deformation parameters are subsequently measured by automated continuous frame-by-frame tracking and motion analysis of speckles within the B-mode images of the myocardium.

经胸斑点跟踪超声心动图左室心肌变形的定量评价

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the ...

In Vivo Tracking of Edema Development and Microvascular Pathology in a Model of Experimental Cerebral Malaria Using Magnetic Resonance Imaging

Cerebral malaria is a sign of severe malarial disease and is often a harbinger of death. While aggressive management can be life-saving, the detection of cerebral malaria can be difficult. We present an experimental mouse model of cerebral malaria that shares multiple features of the human disease, including edema and microvascular pathology. Using magnetic resonance imaging (MRI), we can detect and track the blood-brain barrier disruption, edema development, and subsequent brain swelling. We describe multiple MRI techniques that can visualize these pertinent pathological changes. Thus, we show that MRI represents a valuable tool to visualize and track pathological changes, such as edema, brain swelling, and microvascular pathology, in vivo.

In Vivo Tracking of Edema Development and Microvascular Pathology in a Model of Experimental Cerebral Malaria Using Magnetic Resonance Imaging

We describe a mouse model of experimental cerebral malaria and show how inflammatory and microvascular pathology can be tracked in vivo using magnetic resonance imaging.

使用磁共振成像实验性脑疟疾模型中的水肿发育​​和微血管病理学的体内追踪

Cerebral malaria is a sign of severe malarial disease and is often a harbinger of death. While aggressive management can be life-saving, the detection of ...