支持HL081171美国国立卫生研究院，美国国立卫生研究院HL080203

1。除招聘<ol><li>除人口<ol><li>受试者招募广告，以满足研究所需的特定人群。 </li><li>这项研究的主题是健康，不吸烟 - 45岁至19岁之间的，没有心脏或肺部疾病的历史。 </li></ol></li><li>知情同意<ol><li>这项研究是由加州大学圣迭戈分校，人类研究保护项目批准。 </li><li>主题是通报了这项研究，如磁场曝光（M​​RI）和呼吸的缺氧和高氧的气体的潜在风险。 如果这个问题是女性生育能力的尿液样本收集的研究开始前，以排除妊娠。虽然磁场的影响是极不可能的，到发育中的胎儿是有害的，确切的潜在风险是未知的。此外，缺氧可能目前对胎儿的风险。基于这些原因，孕妇被排除在研究之外。 </li></ol></li><li>安全筛选议员 我们所有的臣民，必须填写一份问卷，禁忌磁共振检查的项目。如果发现禁忌，主体是从研究中排除。 </li></ol> 2。制备<ol><li>体格检查<ol><li>采访主题是关于他们的身体健康和生活习惯，并收到一个简短的体检由持牌医生。 </li><li>这个题目的身高和体重也衡量。这些值被用来估计肺功能测试和特定吸收率（SAR）的预测值。特区的估计是很重要的，因为有潜在主体的组织，从无线电频率（RF）能量要产生的MR影像加热。 </li></ol></li><li>肺功能测试 肺容积测量使用直立的姿势肺活量测定。受执行到一个手持式肺活量计（EasyOne肺功能，医疗技术安多弗）吹肺功能测试。一个鼻夹是用来确保所有的空气被驱逐出口。肺功能数据采集一式三份，以确保可靠的数据。肺功能测试的质量必须符合美国胸科学会/欧洲呼吸学会标准 5 。 </li></ol> 3。接受磁共振研究<ol><li>培训会议过程中产生屏气的一个可靠的功能残气量（FRC）肺容积。 收购时肺FRC是我们的肺部图像。这是很容易达到的肺容积，并提高信​​噪比图像中的质子密度的增加，。我们的科目训练，舒适重现此肺容积。如果这个问题在我们的研究之一是首次参展，本次培训会议之前完成主体进入MR扫描仪。由于扫描仪采集过程中的声音，图像采集的录音播放的问题，和主题是执教，而他们的实践自己的呼吸同步录音。 </li><li>呼吸设置<ol><li>吸气的设置 吸气管连接的聚酯薄膜气体包装袋，将举行任高氧和缺氧的气体，或常氧的空气，并通过切换阀（单活塞滑动式™阀和控制器4285A，汉斯鲁道夫）管理。阀检查正常运转。 管理主体的启发气体，气体包装袋，在扫描仪室，并连接到不同氧气浓度在致辞控制台室的煤气罐。气体被添加到包通过操纵煤气罐监管研究员。 研究者必须通过控制台房窗口监视袋，以确保供气量是足够的，以确保主体有足够的气体正常，激发。 F的第I O 2的高氧和缺氧气体，分别为1.0和0.125 。用于室内空气常氧气。 </li><li>呼气时的设置 呼气的呼吸管是足够长的连接通过直通代谢车在致辞控制台室（TrueOne 2400，ParvoMedics）在磁共振扫描仪的主题。 代谢车措施过期的空气量，以及混合呼气O 2和CO 2浓度。根据这些参数，还可以计算各种呼吸系统分册，如潮气量，耗氧量（五O 2），二氧化碳生产（五CO 2），和呼吸商。 这是必要的O 2和CO 2传感器和流量计校准之前，每一个研究。一名调查员校准与代谢车经营softwar按照内置的指示的代谢车系统E. O 2和CO 2传感器调整两点校准（2 = 0.16和英国外交及联邦事务部2 = 0.04）之间的校准气体和室内空气（2 = 0.2098和英国外交及联邦事务部2 = 0.00）。通过使用一个标准化的的3升注射器流量计校准。的调查泵3公升卷的空气在室温和大气压到了通过的呼气呼吸配备一个汉斯鲁道夫2路非，再呼吸阀，是连接主体的的相同管代谢车面具。为了让各种呼吸流速，这种标定进行至少五次洪峰流量从50升/分钟ATPS 80升/分钟休息测量不等。在油管和喉舌量的计算和科目呼吸这样呼气管长度所造成的延迟时间校正数据相结合。 </li><li>面膜 冷消毒硅胶面具（7400系列Oro的鼻罩，汉斯鲁道夫）安装的主题，让提供不同的气体混合物和整个成像会议的代谢和通气数据的采集（大小:娇小，小型，中型，大型和特大型）。大多数成人科目都配有小型，中型或大型的口罩。 掩码配备一个预消毒非，再呼吸阀（双向非，再呼吸阀T -形状™配置，2600中期，2700大，汉斯鲁道夫）是固定在主体的脸上一个网状的附件，并检查有无泄漏。然后，吸气和呼气管连接。 </li></ol></li><li>议员设置<ol><li>主体仰卧扫描仪对足，孔上滑台移动到磁共振扫描仪。 </li><li>枕头和泡沫垫是用来最大限度地提高主体的舒适性。脉搏血氧仪（7500，燕牌）是放在主体的手指，监测血氧饱和度，心率，这是特别重要的主题是低氧时。 </li><li>一个心电图电极片放在主体的胸部。这使得动脉自旋标记（ASL）的MR序列被选通的QRS波群。 </li><li>一旦题目是戴着面具，他们不能轻易与研究人员沟通。挤压球是定位在主体的手，并在地方录音。这使得为​​主体，以提醒办案人员在任何时候，他们需要援助。 </li><li>耳塞主体，以保护他们从扫描仪所产生的噪音。 </li><li>三名议员的幽灵放在主体的胸部。的幽灵是用来量化在后处理过程中的MR信号特点。 </li><li>躯干线圈放置在主体的胸部上的幽灵。躯干线圈是用来增加信号相比，降低了接收器和主体之间的物理距离的体​​线圈MR图像的信噪比。最后，主体是用毯子覆盖，以确保他们的舒适。 </li></ol></li></ol> 4。 MR扫描<ol><li>扫描之前<ol><li>这个题目是问躺在MRI扫描表的第一脚。然后扫描工作台移动到核磁共振成像扫描仪的中心课题孔。 </li><li>扫描仪操作员经常会谈到这个问题，以确保舒适的主体，并提醒他们挤挤球，如果他们需要帮助。 </li><li>调查监测心电图， 氧饱和度，潮气量，五O 2和V的CO 2。最初几分钟的监测尤为重要，以确保高质量的数据;如果这些数字是在预期范围内，必须反复校正和口罩和管路泄漏检查。 </li></ol></li><li>成像考试序列<ol><li>本地化顺序是先收购获得的解剖图像，以确定躯干内安置成像片。 </li><li>在矢状面 - 后距离是最大的部分右肺前选择一个切片。切片厚度通常为15毫米，视野为40厘米× 40厘米。 </li></ol></li><li>动脉自旋标记 动脉自旋标记-流动敏感交替反转恢复与一个额外的射频脉冲序列，半傅立叶采集单次快速自旋回波（HASTE）成像计划（海拨更公平）是用来获取区域灌注数据1,2 。 <ol><li>主题将听到的声音对的，"砰，砰"，说明磁标记和图像采集。第一次撞击的声音是肖尔比第二。这种声音的差异是明显的。在这些声音对之间，主体必须完成一个呼吸循环:呼吸和呼吸，事先到下一对。在对声音的，这个问题必须在财务汇报局屏气。 </li><li>主体是一个形象收购的试运行，在此期间，受试者做法呼吸，他们熟悉之前，他们把扫描仪（如上所述）。 </li><li>议员运营商评估基础上的隔膜运动的肺部图像质量。如果运动是最小的ASL测量开始。研究人员监测潮气量。近似​​目标潮气量是500-700毫升的正常通风与阀门的额外死亡空间一致。 </li><li>量化肺灌注的基本原则是参考1和2中所述的细节。在此MR序列，两个不同的心脏门控图像获得一个5秒的时间间隔，在它们之间。形象标记和图像采集（即第一次爆炸声和第二次爆炸声之间）之间的时间设置为80％的RR间隔，以便收集的血液收缩压弹射。从血液中的信号是两种不同的方式准备。在一个图像的血液和组织内和外的图像切片的纵向磁化反转，导致血液和组织非常低的信号。在第二幅图像，反转是只适用于成像片，结果从外成片的图像切片，血液流入，具有很强的MR信号。当两个图像中减去，从而抵消了平稳信号，结果是一个收缩期射血时间内交付的图像切片血液定量地图。分辨率为256 × 128像素，因此，体素大小〜1.5 ×〜3.1x的15毫米（〜0.07厘米3）。 </li></ol></li><li>龙质子密度 此外翔升图像，我们还可以使用多回波快速梯度回波序列（mGRE）来衡量肺癌质子密度3。这允许灌注测量毫升/分钟/ g和6胸廓内肺组织变形的帐户表示。这个顺序是运行两次，躯干线圈和体线圈。 <ol><li>在此质子密度图像采集，问题会听到连续的噪音，将持续约10秒钟。在此期间，受试者必须屏住呼吸，并留在财务汇报局。 量化肺癌质子密度的基本原则是在参考文献3。该决议是64 × 64像素;因此，体素大小为6.3〜X〜6.3 × 15毫米（约0.59厘米3）。 </li></ol></li><li>切换吸气气体<ol><li>在这项研究气体与F I O 2 = 0.21（常氧/间空气），F的第I O 2 = 0.125（缺氧），和F I O 2 = 1.00（高氧）在主体之间的平衡顺序，虽然这些都可以多种多样，需要的话，与研究目标相一致</li><li>一个主题后达到稳态指定的条件为特定气体（约20分钟）7，灌注和质子密度，测量获得的。在这种情况下，暴露前成像气体的20分钟内选择，因为虽然发生在几秒钟内开始缺氧性肺血管收缩反应，肺泡缺氧的反应是不是最大的，直到〜20分钟8，与这一目标相一致特别研究。 </li></ol></li></ol> 5。后处理在MATLAB编程环境中使用自定义开发的软件完成后期处理。 <ol><li>线圈的不均匀性校正 通过均质体线圈和不均匀躯干线圈（4.1节）中使用配对mGRE图像，所有的血流量和质子密度图像校正线圈的不均匀性为主题的主题的基础上6。这种方法是参考6和9。 </li><li>密度归灌注<ol><li>一旦减去ASL的形象是线圈不均匀纠正，量化区域的肺血流量是每分钟每立方厘米（体素）毫升（血）。 </li><li>密度归灌注毫升每分钟每克水（血）为单位表示的计算方法是除以质子密度图像灌注毫升每分钟（每克肺组织+血）翔升形象。 </li><li>一个基于互信息技术，包括平移和旋转，利用注册的ASL和质子密度图像，并翔升灌注图像是由质子密度由体素的形象上获得一个体素与躯干线圈基础6,9。这种方法也参考6和9。 </li></ol></li><li>数据分析 上文所述（肺癌质子密度和密度归灌注）收购对于每一个图像，数据分析以下列方式。 <ol><li>对于每一个图像，平均计算密度规范化灌注。 </li><li>灌注异质性的三个不同指标的计算方法。这些是:1）相对分散4,10,11，也称变异系数，全球范围内的异质性定义为标准差的比率平均灌注在其中较大的相对分散，异质的灌注分布; 2）分形维数（DS）7，独立的空间异质性，是规模指数，其中的值各不相同（同质化）1.0和1.5（空间随机）; 3）几何标准偏差，也对全球尺度之间异质性，但基于日志正常模式分布 2 。 </li></ol></li></ol> 6。代表性的成果生理数据列于表1。在缺氧心率增加和饱和度下降。通气缺氧时的8.31升/分钟BTPS，7.04升/分在常氧和6.64升/分钟时氧。潮气量为0.72大号在常氧，缺氧时，0.69大号过程中氧和0.67大号。缺氧增加通风和潮气量的风险，而氧减少通风和潮气量。 三密度归灌注在三个不同吸入氧浓度（:0.125，常氧:0.21，而高氧:缺氧1.00）收集到的图像从一个主题（男，30岁）获得如图1所示。灌注异质性的数据分析结果列于表2。由此可以看出，缺氧加重相对分散，但其他指数大致维持不变。 图2显示，吸入氧浓度的垂直分布密度归灌注的影响，平均高度低于10厘米肺癌的最依赖的部分和10厘米以上的每1厘米。 10厘米以上的所有数据点的平均值，并显示为一个数据点。 <table border="1"><tbody><tr><td>&nbsp;</td><td> 缺氧 </td><td> 常氧 </td><td> 高氧 </td></tr><tr><td>心率（BPM） </td><td> 60 </td><td> 51 </td><td> 50 </td></tr><tr><td> SPO 2 </td><td> 86 </td><td> 99 </td><td> 100 </td></tr><tr><td> V E BTPS（L / min的） </td><td> 8.31 </td><td> 7.04 </td><td> 6.64 </td></tr><tr><td> V T BTPS（L） </td><td> 0.76 </td><td> 0.69 </td><td> 0.67 </td></tr><tr><td> F E O 2（％） </td><td> 8.85 </td><td> 17.27 </td><td> - </td></tr><tr><td> F E CO 2（％） </td><td> 3.41 </td><td> 3.60 </td><td> 3.20 </td></tr><tr><td> VO 2 STPD（L / min的） </td><td> 0.25 </td><td> 0.22 </td><td> -* </td></tr><tr><td> VCO的2 STPD（L / min的） </td><td> 0.23 </td><td> 0.21 </td><td> 0.18 </td></tr></tbody></table> 表1，在生理数据扫描会话。 * VO 2时的主体是100％的氧气呼吸，不能很容易地测量（详情请参阅12）。 <table border="1"><tbody><tr><td>&nbsp;</td><td> 缺氧 </td><td> 常氧 </td><td> 高氧 </td></tr><tr><td>相对分散</td><td> 1.07 </td><td> 0.85 </td><td> 0.87 </td></tr><tr><td>分形维数</td><td> 1.24 </td><td> 1.26 </td><td> 1.26 </td></tr><tr><td>几何标准偏差</td><td> 2.41 </td><td> 2.11 </td><td> 2.38 </td></tr></tbody></table> 表2。肺灌注异质性三个指标。 <img src="/files/ftp_upload/2712/2712fig1.jpg" alt="图1"/> 图1三种不同密度归灌注吸入氧浓度的影响。 1.1:缺氧（0.125），1.2:常氧（0.21），1.3:高氧（1.00）。规模是3厘米（白色实线）。答:前，P:后，我:自卑，和S:上级指示，分别。 <img src="/files/ftp_upload/2712/2712fig2.jpg" alt="图2"/> 图2三种不同吸入氧浓度的垂直分布的密度归灌注的影响。平均密度归灌注引力在同一平面内1厘米的箱，在肺最依赖的一部分，从0厘米，继续最nondependent部分。 10厘米以上的所有数据点的平均值，并显示为一个数据点。 误差线表示在这架飞机的密度归灌注值的标准偏差。缺氧数据以红色，常氧数据为蓝色，和绿色的高氧数据。

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这种方法使测量吸入氧浓度的空间分布上的肺血流量，在MR扫描环境中使用基本的生理技术的影响。定量质子成像肺的生理技术结合使用是相对容易实现。 为了确保良好的质量测试，最重要的一步是培训的主体，屏气，在正确的肺容积和成像序列同步。由于ASL和质子密度图像上的FRC肺容积的可重复性依赖，任何膈肌或胸壁运动，会导致这些图像的位置不正。训练有素的科目是...

<table border="1"><tbody><tr><th>设备</th><th>公司</th><th>模型</th></tr><tr><td>磁共振成像</td><td>通用电气公司</td><td> 1.5 T GE HDX EXICITE twinspeed扫描器</td></tr><tr><td>代谢车</td><td> ParvoMedics </td><td> TrueOne 2400 </td></tr><tr><td>脉搏血氧仪</td><td>燕牌</td><td> 7500 </td></tr><tr><td>肺活量计</td><td>医疗技术安多弗</td><td> EasyOne diagonostic肺活量计</td></tr><tr><td>面膜</td><td>汉斯和鲁道夫</td><td> 7400系列口腔鼻面具，小型，中型，和大型</td></tr><tr><td>阀门</td><td>汉斯和鲁道夫</td><td>双向非再呼吸阀T形™配置，2600中等。 2700大</td></tr><tr><td>头紧定</td><td>汉斯和鲁道夫</td><td>头帽（成人的大小），带锁定夹。 </td></tr><tr><td>气动方向控制阀和控制器</td><td>汉斯和鲁道夫</td><td>单活塞滑动式™阀和控制器4285A </td></tr><tr><td>非扩散的气体收集袋</td><td>汉斯和鲁道夫</td><td> 6100（100升）。 </td></tr><tr><td>管</td><td> VacuMed </td><td>清洁博尔油管108"，1-3/8"外径配件</td></tr><tr><td>幻影</td><td>导师</td><td>布雷斯特植入回合，250cc组</td></tr><tr><td> MATLAB </td><td> The MathWorks公司</td><td></td></tr></tbody></table>

magnetic resonance imaging quantification of pulmonary perfusion using calibrated arterial spin labeling

这演示了磁共振成像的方法来衡量的肺血流量的空间分布在健康受试者在常氧（启发O 2的分数（F的第I O 2）= 0.21），缺氧（F的第I O 2 = 0.125），氧（F的第I O 2 = 1.00）。此外，主体的生理反应是在MR扫描环境监测。从矢状切片功能残气量在右肺呼吸保持在1.5 T GE核磁共振成像扫描仪在MR图像。动脉自旋标记序列（海拨更公平）是用来测量被用来量化区域的质子（即H 2 O的空间分布， 肺血流量1,2和多回波快速梯度回波序列（mGRE ）3）密度，使每个体素（毫升血液每分钟每克肺组织）的密度标准化灌注量化。 配备2路非再呼吸阀用气动开关阀和口罩，介绍了不同氧气浓度的磁共振扫描仪的主题，通过吸入气管。一个新陈代谢的车收集呼气时气体通过呼气管。混合呼气O 2和CO 2的浓度，氧气消耗，二氧化碳生产，呼吸交换率，呼吸频率和潮气量进行测量。使用脉冲血氧饱和度监测心率和血氧饱和度。从一个正常人获得的数据表明，正如所料，心率明显高于缺氧（60次），比在常氧（51）或氧（50）和动脉血氧饱和度（SPO 2）缺氧时减少到86％ 。平均通风是8.31升/分钟BTPS，在缺氧过程中，7.04升/分在常氧和6.64升/分钟时氧。潮气量为0.76大号在常氧，缺氧时，0.69大号过程中氧和0.67大号。 代表量化的ASL的数据显示，平均密度归灌注8.86毫升/分/克，8.26毫升/分/ G在常氧和8.46毫升/分/ G分别在高氧，缺氧时。在这个问题上，相对分散，全球异质性的指标 ，4增加了在缺氧（缺氧时为1.07，0.85在常氧，并在高氧0.87），而分形维数（DS），另一种异质性指数，反映血管的分支结构，不变（1.24缺氧时，在常氧1.26和1.26期间氧）。 概述。该协议将展示的数据采集来衡量使用磁共振成像技术被称为动脉自旋标记（ASL），常氧，缺氧，高氧条件下的非侵入性肺灌注的分布。 理由:肺血流量和肺质子密度，采用MR技术的测量提供高空间分辨率的图像，可以量化和执行几个不同的生理条件下重复测量的能力。在人类研究中，PET，SPECT和CT是常用的替代技术。然而，这些技术涉及暴露于电离辐射，因而不适合人类受试者重复测量。

Watch this Scientific Journal Video about Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling at JoVE.com

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

一个磁共振成像方法研究各种生理条件下的肺血流量的分配，在这种情况下接触到三个不同吸入氧浓度，缺氧，常氧和氧，是描述。利用此技术在MR扫描环境中的人肺的生理学研究技术。

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, ...

magnetic-resonance-imaging-quantification-pulmonary-perfusion-using

Research

JoVE Journal

Medicine

13.4K 次观看.  University of California San Diego - UCSD. 一个磁共振成像方法研究各种生理条件下的肺血流量的分配，在这种情况下接触到三个不同吸入氧浓度，缺氧，常氧和氧，是描述。利用此技术在MR扫描环境中的人肺的生理学研究技术。

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

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

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 ...

Hemodynamic Characterization of Rodent Models of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary vasculature characterized by endothelial cell apoptosis, smooth muscle proliferation and obliteration of pulmonary arterioles. This in turn results in right ventricular (RV) failure, with significant morbidity and mortality. Rodent models of PAH, in the mouse and the rat, are important for understanding the pathophysiology underlying this rare disease. Notably, different models of PAH may be associated with different degrees of pulmonary hypertension, RV hypertrophy and RV failure. Therefore, a complete hemodynamic characterization of mice and rats with PAH is critical in determining the effects of drugs or genetic modifications on the disease. 
Here we demonstrate standard procedures for assessment of right ventricular function and hemodynamics in both rat and mouse PAH models. Echocardiography is useful in determining RV function in rats, although obtaining standard views of the right ventricle is challenging in the awake mouse. Access for right heart catheterization is obtained by the internal jugular vein in closed-chest mice and rats. Pressures can be measured using polyethylene tubing with a fluid pressure transducer or a miniature micromanometer pressure catheter. Pressure-volume loop analysis can be performed in the open chest. After obtaining hemodynamics, the rodent is euthanized. The heart can be dissected to separate the RV free wall from the left ventricle (LV) and septum, allowing an assessment of RV hypertrophy using the Fulton index (RV/(LV+S)). Then samples can be harvested from the heart, lungs and other tissues as needed.

Pulmonary arterial hypertension (PAH) is a disease of pulmonary arterioles that leads to their obliteration and the development of right ventricular failure. Rodent models of PAH are critical in understanding the pathophysiology of PAH. Here we demonstrate hemodynamic characterization, with right heart catheterization and echocardiography, in the mouse and rat.

肺动脉高压的啮齿动物模型的血流动力学特性

Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary vasculature characterized by endothelial cell apoptosis, smooth muscle ...

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 ...

Quantification of Levator Ani Hiatus Enlargement by Magnetic Resonance Imaging in Males and Females with Pelvic Organ Prolapse

Here we present a protocol to examine the levator ani hiatus in males and females with pelvic organ prolapse, during the Valsalva maneuver and while evacuating acoustic gel, using a horizontally oriented 1.5 T magnetic resonance (MR) scanner. On midsagittal images, the vertical distance of pelvic organs is measured in millimeters relative to the hymen plane (female) and to the lower border of the symphysis pubis (male), preceded by - (above) or + ( below) signs. On axial images, the levator ani area is calculated in square centimeters with a free-hand tracing method from three key images, passing through the midsymphysis (level I), tangential to the lower border of the symphysis (level II), and at the maximal anterior rectal wall bulging (level III). Areas at rest and strained are compared to find evidence of a percentage of increase. The purpose is to provide objective evidence of the maximal extent of pelvic organs descent and hiatus enlargement without the interference of foreign objects or the examiner&#39;s proximity, so as to overcome the limitations of pelvic examination and transperineal sonography (i.e., subjectivity and sex-related limitations [female only]).

Here we present a protocol to standardize the measurement of the levator ani hiatus size&#160;by magnetic resonance imaging. The purpose is to extract biomechanical inferences from image analysis by comparing resting and straining values in patients of both sexes with pelvic prolapse, using consistent anatomical bony landmarks.

男性和女性盆腔器官脱垂的磁共振成像对左旋的定量研究

Here we present a protocol to examine the levator ani hiatus in males and females with pelvic organ prolapse, during the Valsalva maneuver and while ...

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 ...

Quantitative Mapping of Specific Ventilation in the Human Lung using Proton Magnetic Resonance Imaging and Oxygen as a Contrast Agent

Specific ventilation imaging (SVI) is a functional magnetic resonance imaging technique capable of quantifying specific ventilation &#8213; the ratio of the fresh gas entering a lung region divided by the region&#8217;s end-expiratory volume &#8213; in the human lung, using only inhaled oxygen as a contrast agent. Regional quantification of specific ventilation has the potential to help identify areas of pathologic lung function. Oxygen in solution in tissue shortens the tissue&#8217;s longitudinal relaxation time (T1), and thus a change in tissue oxygenation can be detected as a change in T1-weighted signal with an inversion recovery acquired image. Following an abrupt change between two concentrations of inspired oxygen, the rate at which lung tissue within a voxel equilibrates to a new steady-state reflects the rate at which resident gas is being replaced by inhaled gas. This rate is determined by specific ventilation. To elicit this sudden change in oxygenation, subjects alternately breathe 20-breath blocks of air (21% oxygen) and 100% oxygen while in the MRI scanner. A stepwise change in inspired oxygen fraction is achieved through use of a custom three-dimensional (3D)-printed flow bypass system with a manual switch during a short end-expiratory breath hold. To detect the corresponding change in T1, a global inversion pulse followed by a single shot fast spin echo sequence was used to acquire two-dimensional T1-weighted images in a 1.5&#160;T MRI scanner, using an eight-element torso coil. Both single slice and multi-slice imaging are possible, with slightly different imaging parameters. Quantification of specific ventilation is achieved by correlating the time-course of signal intensity for each lung voxel with a library of simulated responses to the air/oxygen stimulus. SVI estimations of specific ventilation heterogeneity have been validated against multiple breath washout and proved to accurately determine the heterogeneity of the specific ventilation distribution.

Specific ventilation imaging is a functional magnetic resonance imaging technique that allows for quantification of regional specific ventilation in the human lung, using inhaled oxygen as a contrast agent. Here, we present a protocol to collect and analyze specific ventilation imaging data.

以质子磁共振成像和氧为造影剂对人肺特异性通气进行定量定位

Specific ventilation imaging (SVI) is a functional magnetic resonance imaging technique capable of quantifying specific ventilation &#8213; the ratio of ...

Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the recognized standard-of-care for blood flow quantification based on phase contrast MRI. While such measurement of blood flow has been possible in adults for decades, methods to extend this capability to fetal blood flow have only recently been developed.
Fetal blood flow quantification in major vessels is important for monitoring fetal pathologies such as congenital heart disease (CHD) and fetal growth restriction (FGR). CHD causes alterations in the cardiac structure and vasculature that change the course of blood in the fetus. In FGR, the path of blood flow is altered through the dilation of shunts such that the oxygenated blood supply to the brain is increased. Blood flow quantification enables assessment of the severity of the fetal pathology, which in turn allows for suitable&#160;in utero&#160;patient management and planning for postnatal care.
The primary challenges of applying phase contrast MRI to the human fetus include small blood vessel size, high fetal heart rate, potential MRI data corruption due to maternal respiration, unpredictable fetal movements, and lack of conventional cardiac gating methods to synchronize data acquisition. Here, we describe recent technical developments from our lab that have enabled the quantification of fetal blood flow using phase contrast MRI, including advances in accelerated imaging, motion compensation, and cardiac gating.

Here we present a protocol for measuring fetal blood flow rapidly with MRI and retrospectively performing motion correction and cardiac gating.