Name: simultaneous pet/mri imaging during mouse cerebral hypoxia-ischemia
Uploaded: 2015-09-20T14:00:00.000+00:00
Duration: 10 min 35 s
Description: Watch this Scientific Journal Video about Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia at JoVE.com

作者要感谢中心的分子和基因组成像加州大学戴维斯分校的生物医学成像部门在Genentech公司。这项工作是由卫生部生物工程研究合作伙伴的授权号R01 EB00993一个国家机构的支持。

所有的动物处理和程序本文所述，并根据动物研究:报告体内实验（到达）的指导方针，按照批准的协会为实验动物的评审评估方案进行（AAALAC）的国际认证机构动物护理和使用委员会在加州大学戴维斯分校。适当的手术不应导致的在动物的任何疼痛或不适的迹象，但如果这些标志观察到，包括的止痛剂或在某些情况下施用安乐死应采取适当的步骤。右侧的动物是任意选择为所描述的单方面过程。 1.单侧颈总动脉（CCA）结扎<ol><li>准备无菌区与定位方便消毒外科手术工具和材料。确保加热垫加热至37℃，温度探针牢固地放置在垫。 ＆＃160;一定要使用一个无菌的悬垂覆盖手术部位。 </li><li>麻醉动物（异氟烷，在空气中1-3％在0.5-1升/分钟），并将其放置在动物的尾背向仰卧位置。检查麻醉按捏脚趾 - 这应该引起任何反应，如果动物是正确麻醉。应用眼药膏的眼睛。 </li><li>申请脱毛霜下颈部使用1-2棉签上胸部区域。等待1-3分钟，然后用湿纱布或酒精棉签去除毛发和奶油。优碘擦拭切口面积以循环的方式从内到外，再换上无菌手术手套。 </li><li>用手术剪，使约1厘米的切口沿着下颈部的中线。小心地用手术剪周围筋膜分开外皮。 </li><li>使用两个麦弗逊式微虹膜缝合镊子，从筋膜分离右侧颈总动脉，注意避免破坏静脉或distur兵迷走神经。 </li><li>使用镊子在右边，exteriorize右侧CCA在稳定的位置。应用数滴盐水以防止干燥。通过右侧CCA下方6-0丝线缝合，结扎，并使用双平结合适的长度（2-3厘米）。任选，结扎用6-0丝线缝合一个第二长度一次。 </li><li>重新定位正确的CCA和使用无菌海绵打开清理多余的液体放倒棉签。关闭切口用6-0丝线缝合。应用利多卡因局部达7毫克/公斤。 </li><li>让动物从麻醉到门诊（约30分钟），回收并进行手术后的监控，直到动物准备成像。 </li></ol> 2.准备成像:系统和硬件检查<ol><li>设置硬件和软件的MRI和PET系统，并检查其功能如下。确保所有物理连接是否牢固和软件设置适当选择。 <ol><li&gt;确保在PET系统是在5℃下使用空气冷却系统的规定的工作温度。 </li><li>摩宠物系统的MRI孔内，对准了使用已知轴偏移视角（FOV）中心的PET和MRI领域。挂载MRI线圈宠物系统的孔内和中心线圈与PET系统和MRI磁体中心。 </li><li>打开PET电子电源和偏置电压（注:步将用乐器不同）。采用68缸戈执行快速（5分钟）的扫描和检查所生成的正弦图，以确保所有探测器的操作。 </li><li>任选获得用于用于共登记用途的PET / MRI变换矩阵数据:填充三维幻影（例如，三填充球）与200微居里的18 F-水溶液和获得15分钟的PET带。获取解剖MRI数据:在扫描控制窗口中，选择多片多回波（MSME）序列（ 见表 1 </strong&gt;的信息）。重复所有三个主要方向:轴向，矢状面和冠状。 </li></ol></li><li>检查输液泵的设置和操作。设置泵每分钟4.44微升，而在恒定输注45分钟提供200微升，对于静脉注射在20克的动物的典型建议的限制的总体积。 </li><li>检查加热器操作，并确认所述温度输出是足以保持动物温热（37℃）。检查温度和呼吸监测工作正常，准备对动物睡觉的动物安置。 </li><li>通过与压缩空气源关闭和 O 2 和 N 2在两个供电:检查O 2和N 2的流量计的操作（O 2在57.2毫克/分和 N 2在0.575克/分0.5升/分钟）来源上。为了避免损坏流量计的危险，不要打开它们没有足够的输入压力。 </li><li>确保异氟醚vaporizer被充分填充。在成像之前，启动异氟烷麻醉流量在1-2％和0.5至1升/分。 </li><li>制备动物床通过确保麻醉，呼吸垫，和加热器系统被安全地和功能性地定位。有关其他的PET /磁共振配准准确度，基准标记（例如，毛细管在相似浓度作为注射成像填充有放射性示踪剂）可以附着到动物床的视野内。 </li></ol> 3.成像工作流程毕竟必要的设备检查完成后，继续成像如下: <ol><li>麻醉用异氟烷的动物，并插入尾静脉导管（28克针，PE-10管小于5厘米）填充有肝素生理盐水（0.5毫升肝素，1000 USP /毫升，在10毫升盐水）。升温动物和/或尾可能提高的导管插入精度。任选放置一滴氰基丙烯酸酯类粘合剂的上插入部位以固定IV线。 </li><li>动物转移到准备好的动物床。确保动物的头是安全的，与上门牙的位置固定在牙齿的酒吧和耳棒，如果正在使用。 </li><li>应用眼药膏的眼睛，以防止干燥。插入直肠探头温度计。确保温度和呼吸读数功能。 </li><li>绘制示踪剂剂量（约600微居里在200μl）注射到肝素化的PE-10管的适当长度 - 约3μm对于PE-10管材和200微升的体积。连接该管道到输液泵的注射器，而另一对尾静脉导管线的一端，注意不要用来在管穿孔。 </li><li>向前滑动动物床到磁体的孔，确保不干扰磁共振线圈的定位和任何线路或电缆，尤其是麻醉管。保证大脑的中心与M的中心对准RI线圈，宠物系统，以及MRI磁体。 </li><li>通过旋转线圈上的调节旋钮，最小化阻抗（检查线圈规格）和频率（300兆赫1 H在7特斯拉的）不匹配，通过观察高功率前置放大器的显示执行调谐的MRI线圈的和匹配。 </li><li> （MRI）的调谐和匹配后，获取侦察图像:选择一种罕见的tripilot序列和运行扫描控制窗口的顺序。检查动物的定位，重复步骤3.5，并根据需要3.6。重置垫片到零值。 </li><li> （MRI）取得局部，点分辨光谱扫描（PRESS）的体积在大脑中:运行PRESS序列（ 见表 1）在一个长方体，尺寸为3.9毫米×6毫米×9毫米。检查水线宽使用CalcLineWidth宏命令。如果在一半最大值（FWHM）值全宽是可以接受的（例如，为0.2ppm），继续到步骤3.10。如果没有，继续执行步骤3。9。 </li><li> （MRI）获取字段映射:运行FieldMap序列（ 见表 1）。通过运行MAPSHIM宏命令，并选择线性和二阶（Z 2）局部调整，使用了多角度的投影垫片（MAPSHIM）产生的数据。重复步骤3.8。 </li><li> （MRI）位置的DWI扫描（ 见表 1）切片的计划:使用几何编辑器，确保收购FOV定位获取的大脑内的利益所需的音量。如果得到的片计划是一致的需要，复制在扫描控制窗口此片计划，所有后续弥散加权成像扫描。开始采集。 </li><li> （PET）随着PET收购准备，并准备开始，启动输液泵。预先确定的延迟，其中从导管盐水已经注入之后，开始以捕获放射性示踪剂的条目的PET收集（ 见表 1）。监控计数率并查找逐渐增加在表明一个成功的注射次数。 </li><li>后10-15分钟，引发缺氧的挑战并行执行步骤3.12。以引发缺氧挑战，关掉医用空气流，并立即功率上的 O 2 和 N 2的流量计与预定的设置来提供8％的氧气和92％的氮气，并减少异氟烷〜0.8％。 请在流量计不功率而不输入压力。 </li><li> （MRI）的同时作为步骤3.12，开始在步骤3.10制备DWI采集（扫描"H1"）。 </li><li> （MRI）的开始DWI采集（扫描"H2"），在步骤3.10制备后立即扫描H1被完成。通过关闭流量计，恢复医用空气流动，异氟醚浓度恢复到基于生理监测一个合适的值完缺氧的挑战。 </li><li> （MRI）收购后缺氧DWI扫描步骤3.10准备。关掉输液泵之后该扫描已完成。 </li><li> （MRI）取得ANATomical图像在轴向平面和径向平面。在扫描控制窗口-选择MSME序列（ 见表 1）。利用几何编辑器，确保收购FOV涵盖了大脑。 </li><li>除去动物，返回到笼卧床时 ​​监测和发病率的迹象，安乐死必要时用CO 2的施用颈椎脱位作为次要方法。 </li></ol>

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JM和SW是基因泰克的员工。

同时解剖MRI和动态DWI-MRI和[18 F] FDG PET数据成功地从实验动物中以下颈总动脉结扎缺氧挑战获得的。这代表了一个强有力的实验范例用于与在大脑局部缺血损伤相关联的快速变化的病理生理的多模成像和可以很容易地扩展到研究其它的PET放射性示踪剂（对于神经炎症的示例标记）和MRI序列，以及介入战略的影响期间或缺血性的挑战后不久。 期间在大脑的HI模型缺氧挑战成功执行的同时PET /磁共振成像，物流必须考虑和方法进行相应调整。可能影响了实验的时间配置的因素​​包括，但不限于:放射性1）源 - 取决于岭diotracer使用的，半衰期的放射性核素，和比活性的要求，这可能会影响动物成像的可能总数; 2）的房间布局 - 这可能会影响管使用，因此注射​​剂量的长度，或可能需要额外的步骤，以保持注射剂量。这也可能对以达到平衡在麻醉管道气体混合物的时间有小的影响; 3）动物体重-部分机构可施加为生存程序 （例如，体重小于1％）的总注射体积上的限制，进而潜在地影响管道的长度和输液泵速率设置; 4）示踪剂输送-推注，输液，或推注加输注递送，可以使用，如通过放射性示踪剂动力学测定和观察到的预期的变化-后两者是特别有用的跟随动态变化24。 的PET和MRI图像采集协议的设计，特别是LY在有限的时间来工作，是在这个实验中的另一个关键因素。如果使用回波平面成像（EPI），为这里提出的基于DWI序列（EPI-DWI），重要的考虑因素包括扫描持续时间，视场，和扩散梯度加权和方向。在调整这些参数，以EPI-DWI固有的问题也必须得到解决，其中包括重影，信号差，和梯度占空比限制。使用呼吸门控的也可以使用，以解决由于问题运动。 表1描述连同在PET硬件，采集参数，和示踪剂输送参数信息所使用的磁共振成像采集参数。对于PET数据的量化，探测器正常化必须应用。虽然在我们的例子中没有这样做，可以采取进一步措施，以实现更精确的定量分析，包括使用分段MRI数据和散射校正衰减校正。前者可能没有必要在小动物如吨衰减他度小和可占使用类似大小的标定物体。根据所使用的磁共振成像序列，它也可能是必要的，以考虑在T2 * 25任何显著BOLD影响。此外，麻醉剂和载气对血糖的影响可能需要使用的 [18 F] FDG的26时加以考虑。 检查应进行，以确保有PET和MRI系统之间没有显著相互干​​扰，或在实验中使用的成像系统和其他仪器之间。根据我们的经验，存在在PET或MRI图像质量没有显著差异单独或同时取得时，尽管我们已经观察到在PET系统计数瞬时损失，由于在诱导快速梯度切换PSAPD基于探测器杂散信号，已注意到由他人12的效果。观察到的另一个问题是RF无伊势从输液泵电源干扰PET探测器采集导致数据丢失。这是通过用实验室品质电源取代了原来的AC适配器解决。更多的PET /磁共振硬件配置在文献中描述的，并且可以根据需要调节本协议容纳独特设置12,27。 所述成像工作流程可以以优化用于不同的MRI脉冲序列或PET示踪剂和捕获方案的条件进行修改。例如，在大脑的HI损伤模型的严重性已显示由被调制，在其他条件下，缺氧11的持续时间。越来越多的挑战，缺氧的长度可允许采集DWI数据，更精细的时间分辨率，或允许用于PET示踪剂更强大的半球形的吸收比较。协议的其它方面可基于可用的资源和人员进行调整。供例如，手术可以交错并以减少的可变性中的CCA结扎和缺氧之间的时间并行运行成像会话。 在这个协议中，同时进行的PET和MRI采集，除了生理挑战，强加在时间方面上彼此相互限制。在优化EPI-DWI序列，发现有额外的扩散方向的同时保持图像质量会增加采集时间超出可接受的范围为在缺氧的挑战进行多次收购。因此，扩散梯度为唯一沿z轴施加。另外，动物模型的适配到成像协议可能需要一些修改 - 在我们的情况下的标准脑缺氧缺血模型，在低氧挑战改变通过注入额外流体（0.2毫升放射性示踪剂）。

在世界范围内，中风死亡的第二大原因和残疾1的一大原因。发生期间和之后急性中风事件生理生化事件的级联反应迅速，与组织的活力，最终的结果2含义发生。脑缺氧缺血（HI），这导致缺氧缺血性脑病（HIE），估计影响高达0.3％和足月和早产，分别3,4- 4％。死亡率在HIE患儿是约15％至20％。在HIE幸存者的25％，永久性并发症发生的伤害，包括智力低下，运动障碍，脑瘫和癫痫3,4的结果。以往的治疗干预还没有被证明值得采纳的护理标准，并达成共识尚未达成，最先进的方法，基于低温，有效降低发病率3,5。其他问题Ø˚F争夺包括低温和患者选择6给药方法。因此，对神经保护和神经复原的战略仍然是一个肥沃的地区研究7。 自1960年以来脑HI大鼠模型已经面世，并随后进行了调整，以小鼠8,9。由于模型和结扎的位置的性质，有对结果因在动物10之间侧支血流差异固有可变性。其结果是，这些车型往往比同类机型，如大脑中动脉闭塞（缺血），更变数。生理变化的实时测量已被证实与激光多普勒血流仪以及弥散加权成像11。脑血液流所观察到的帧内动物变性期间，并立即缺氧后，以及在急性成果，如梗死体积和神经赤字，建议同时采集多的数据和关联将是有益的。 在同时进行正电子发射断层扫描（PET）和磁共振成像（MRI）的最新进展已经允许在临床前成像12-14中的新的可能性。这些混合，结合系统临床前应用的潜在优势在文献15,16已经描述。例如，当事件如中风的每个实例本身表现独特，迅速变化的病理生理 - - 尽管许多临床前的问题可以通过成像个别动物顺序的或通过成像单独动物组，某些情况下加以处理，使其理想，甚至是必要使用同步测量。脑功能成像提供了这样一个例子，在这里同时2-脱氧-2-（18 F）氟ᴅ葡萄糖（[18 F-FDG）PET和布卢D-氧水平依赖（BOLD）MRI最近被证明在大鼠胡须刺激研究14。 在这里，我们展示了一个发生缺氧缺血性中风的大脑生理学是不是在稳定状态的过程中同时进行PET / MRI成像，但在缺氧的挑战，而不是迅速和不可逆的变化。变化水扩散，如通过MRI测定，通过从弥散加权成像（DWI）衍生的表观扩散系数（ADC）量化的，已被充分表征的冲程在临床和临床前数据17,18。在动物模型如MCAO，水在受影响的脑组织的扩散迅速下降是由于生物能量级联导致细胞毒性水肿18。在ADC这些急性变化也观察到脑缺氧缺血11,19的啮齿动物模型。 [18楼] FDG PET显像已应用于中风患者，以评估改变当地的冰川ucose代谢20，和一个小数目的体内动物研究还使用[18 F] FDG的21，包括在脑缺氧缺血模型22。总的来说，这些研究显示，缺血区减少葡萄糖的利用，尽管使用再灌注模型的一项研究发现，与后来的心肌梗塞发展23这些代谢的变化无关。这是相对于已与不可逆受损芯 21相关联的扩散变化。因此，为了能够获得笔划的进化过程中，来自于[18 F] FDG PET及DWI以同时的方式中的补充信息是很重要的，因为这是可能产生关于损伤的进展，产生的影响的有意义的信息治疗干预。我们在这里描述的方法很容易适合与各种PET示踪剂和MRI序列的使用。例如，[15 O] H 2 O宠物随着DWI和灌注加权图像（PWI）从MRI图像可以被用于进一步探索缺血半暗带的开发和验证行程摄像视野内的电流的技术。

<table><tbody><tr><td>Surgery</td><td></td><td></td><td></td></tr><tr><td>Surgical scissors</td><td>Roboz</td><td>RS-5852</td><td></td></tr><tr><td>Forceps</td><td>Roboz</td><td>RS-5237</td><td></td></tr><tr><td>Hartman mosquito forceps</td><td>Miltex</td><td>7-26</td><td></td></tr><tr><td>2x McPherson suturing forceps, 8.5 cm</td><td>Accurate Surgical &amp;amp; Scientific Instruments</td><td>4473</td><td>It is useful to reduce the opening width with a band on the forceps used to hold the carotid artery</td></tr><tr><td>6-0 silicone coated braided silk suture with 3/8 C-1 needle</td><td>Covidien Sofsilk</td><td>S-1172</td><td></td></tr><tr><td>Homeothermic blanket system</td><td>Harvard Apparatus</td><td>507220F</td><td></td></tr><tr><td>Super glue</td><td>(Generic)</td><td></td><td></td></tr><tr><td>Hypoxia</td><td></td><td></td><td></td></tr><tr><td>Flowmeter for O2</td><td>Alicat Scientific</td><td>MC-500SCCM-D</td><td></td></tr><tr><td>Flometer for N2</td><td>Alicat Scientific</td><td>MC-5SLPM-D</td><td></td></tr><tr><td>O2 meter</td><td>MSA</td><td>Altair Pro</td><td></td></tr><tr><td>Imaging</td><td></td><td></td><td></td></tr><tr><td>7.05 Tesla MRI System</td><td>Bruker</td><td>BioSpec</td><td>20 cm inner bore diameter with gradient set. Paravision 5.1 software.</td></tr><tr><td>Volume Tx/Rx 1H Coil, 35 mm ID</td><td>Bruker</td><td>T8100</td><td></td></tr><tr><td>PET system</td><td>(In-house)</td><td></td><td>4x24 LSO-PSAPD detectors,&lt;br/&gt; 10x10 LSO array per detector,&lt;br/&gt; 1.2 mm crystal pitch and 14 mm depth. 14 x 14 mm PSAPD. FOV: 60x35 mm. 350-650 keV energy window. 16 nsec timing window.</td></tr><tr><td>Vessel cannulation Dumont forceps</td><td>Roboz</td><td>RS-4991</td><td></td></tr><tr><td>PE-10 polyethylene tubing</td><td>BD Intramedic</td><td>427401</td><td></td></tr><tr><td>Infusion pump</td><td>Braintree Scientific</td><td>BS-300</td><td></td></tr><tr><td>Animal monitoring &amp;amp; gating equipment</td><td>Small Animal Instruments Inc.</td><td>Model 1025</td><td>Only respiration monitoring used</td></tr><tr><td>Animal bed with temperature regulation</td><td>(In-house)</td><td></td><td></td></tr></tbody></table>

simultaneous pet/mri imaging during mouse cerebral hypoxia-ischemia

在缺氧脑缺氧缺血反映在受影响细胞生物能量扰动后组织水扩散和葡萄糖代谢的动态变化会发生。磁共振弥散加权成像（MRI）标识被损坏，造成无法恢复的区域，缺氧，缺血。在受影响的组织对葡萄糖的利用改变可以是可检测的正电子发射断层摄影术的2-脱氧-2-（18 F）的氟ᴅ葡萄糖（[18 F] FDG）摄取（PET）成像。由于损伤的动物模型的快速和可变性质，采集数据的两种模式的必须同时以有意义地关联的PET和MRI数据执行。此外，在缺氧缺血损伤由于血管差异的动物间变异性限制来分析多模态的数据和观察到的变化的一组，明智的做法，如果未在个体对象同时采集的数据的能力。该方法P反感这里允许一个之前在相同的动物获得两个扩散加权MRI和[18 F] FDG摄取数据，在此期间，为了询问即时的生理变化的缺氧攻击后。

图1显示了普通颈动脉的结扎正确之前，闭合伤口用6-0丝线缝合的结果。 在该方法中，从拍摄得到的数据是高度依赖于实验，这又决定，并且还决定由实验的限制包括图像捕获方案和设备设置的时间安排。这些及其他因素的进一步探讨在讨论部分。与本文描述的协议中，设备（图2A）的物理安装允许进行不间断的多模态图像采集之前，期间，和（图2B）快速引入的低氧挑战（图2C）后。 在这种动物模型中，与许多缺血性中风模型中，改变扩散是可检测后迅速侮（见图3A为一个representat香港专业教育学院例子）。由于我们的方法不从根本上改变了大脑的HI模型，扩散的变化可以在一个坚固的方式再现- 图3B展示了对侧（非闭合，左）之间在ADC的Z中的不断发展的百分比差异（ADC在z方向上）和同侧（闭塞，右）大脑，％LR，侧面（每组6为扫描H2中，n = 5的所有其他时间点）。正如预期的，对大脑减少作为损伤的闭塞侧ADC值的进展。 图3C示出了从DWI序列的一例冠状切片，以及一个矢状切片展示在FOV（8毫米）的的有限的轴向范围顺序使用。关于所使用的DWI回声平面成像（EPI）序列所施加的限制细节在讨论部分描述。总之，与所提出的成像框架所获得的图像质量取决于系统的性能特点，和EPI基于在particul DWI序列AR可能会暴露不理想的硬件条件或采集参数（ 见图5B）。那名基线和后续的ADC％LR值（P &lt;0.05，非配对t检验 ）之间观察显著的差异表明，这是一个强大的参数，用我们的实验装置来询问。 并发的变化的ADC，半球形差异观察[18 F] FDG的摄取开始缺氧挑战之后和期间的扫描H2（％11平均LR差中，n = 3）。在二位三通的情况下，同侧的 [18 F] FDG摄取缺氧（参见图4为代表例）后相对降低至对侧的摄取，尽管这是不正确的在所有的情况下很可能是由于动物的变异性。 图5A示出一个实例，其中两个半球之间的[18 F] FDG摄取的相对差异并不如预期中的一种动物（蓝色）。 图5A还显示了一个例子，而18 F-FDG摄取如预期缺氧，在扫描H2年底动物死亡。 <img alt="图1" src="/files/ftp_upload/52728/52728fig1.jpg" /> 图中的右颈总动脉结扎用6-0丝线缝合的1。实施例的动物是仰 ​​卧而其头尖朝图像的底部。切口周围的区域被脱毛，并且切口被关押钳可视化开。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/52728/52728fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" src="/files/ftp_upload/52728/52728fig2.jpg" /> 图2.（A）的物理布置的代表图<html>设备。在PET插入件被定位在磁体的孔中，和所述MRI线圈依次定位在PET刀片的孔中。动物床，伴随着生理监测（未示出呼吸垫），麻醉的行，IV导管跑入该孔，如图所示。虚线环表示的安全余量 ​​为杂散磁场-可能有必要放置设备与该区域之外，但在MRI室（以下所有安全防范措施）内的磁性组分 （B）图总结了实验的时间进程（C）的低氧挑战开始后立即递送到动物中的 O 2水平初步改变代表性的结果。在大约1分钟，在低氧条件可以实现，如通过一个O 2米放入0.5升感应箱（未示出）测得的，单线与麻醉系统。<html> rge.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 <img alt="图3" src="/files/ftp_upload/52728/52728fig3.jpg" /> 图在基线，并通过后缺氧获得的参数ADCž图3（A）为例。（B）剧情呈现％LR差异ADCž从基线到后缺氧。星号表示一个显著差异（p &lt;0.05，非配对t检验 ）比较基准值。误差线表示+/-一个EPI-DWI采集（轴向，矢状面和三维视图来显示视野的范围内）的一个标准偏差。（C）为例。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/52728/52728fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> /ftp_upload/52728/52728fig4.jpg"/&gt; 图4（A），动物的表现[18楼] FDG摄取的冠状沟和横向切片。 PET图像是在前台和被配准并融合，在后台进行可视化的解剖学MRI图像。在PET数据在所有帧求和。（B）在相同的动物，[18 F] FDG为对侧大脑半球（蓝色）和同侧半球（红色）。时间的活动曲线<a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/52728/52728fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。 。</a> <img alt="图5" src="/files/ftp_upload/52728/52728fig5.jpg" /> 对侧（固体）和同侧（点）半球[18楼] FDG摄取的图5（A）时间活性曲线-在同一轴线上显示的是一个意外的[18楼] FDG时间例子在H2年底活性曲线（蓝色）和动物死亡（45分钟，绿色）。（B）重影假象由于潜在的基于硬件的RF故障。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/52728/52728fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td>成像习得参数和硬件采购</td><td></td></tr><tr><td></td><td></td></tr><tr><td>扩散磁共振成像（EPI-DWI） </td><td></td></tr><tr><td> Acqusition时间</td><td> 15分钟</td></tr><tr><td>矩阵大小</td><td> 256×64 </td></tr><tr><td>片</td><td> 10 </td></tr><tr><td> FOV </td><td> 30×14×8毫米</td></tr><tr><td>体素的大小</td><td> 0.117 x 0.219×0.8毫米的</td></tr><tr><td>有效的光谱带宽</td><td> 150千赫</td></tr><tr><td> TE </td><td> 41毫秒</td></tr><tr><td> TR </td><td> 3000毫秒</td></tr><tr><td>平均值</td><td> 6 </td></tr><tr><td> k空间段</td><td> 16 </td></tr><tr><td> b值</td><td> 0，400，800秒/毫米2 </td></tr><tr><td></td><td></td></tr><tr><td>解剖MRI（MSME） </td><td></td></tr><tr><td>采集时间</td><td> 5分钟</td></tr><tr><td>矩阵大小</td><td> 256×256 </td></tr><tr><td>片</td><td> 16 </td></tr><tr><td> FOV </td><td> 30×22×12.8毫米</td></tr><tr><td>体素的大小</td><td> 0.117 x 0.086×0.8毫米的</td></tr><tr><td> TE </td><td> 14毫秒</td></tr><tr><td> TR </td><td> 1000毫秒</td></tr><tr><td>平均值</td><td> 1 </td></tr><tr><td>重复次数</td><td> 1 </td></tr><tr><td></td><td></td></tr><tr><td>点分辨光谱 扫描（PRESS） </td><td></td></tr><tR&gt; <td>采集时间</td><td> 15秒</td></tr><tr><td>体素的大小</td><td> 3.9×6×9毫米</td></tr><tr><td> TE </td><td> 20毫秒</td></tr><tr><td> TR </td><td> 2500毫秒</td></tr><tr><td>平均值</td><td> 6 </td></tr><tr><td></td><td></td></tr><tr><td> FieldMap </td><td></td></tr><tr><td>采集时间</td><td> 1分21秒</td></tr><tr><td>第一TE </td><td> 1.49毫秒</td></tr><tr><td>第二TE </td><td> 5.49毫秒</td></tr><tr><td> TR </td><td> 20毫秒</td></tr><tr><td>平均值</td><td> 1 </td></tr><tr><td></td><td></td></tr><tr><td> PET采集，直方图​​， 和重建参数</td><td></td></tr><tr><td>曳光弹</td><td> [18楼] FDG </td></tr><tr><td>输液率</td><td> 4.44微升/分钟</td></tr><tr><td>采集时间</td><td> 60分钟</td></tr><tr><td>每片图像尺寸</td><td> 128×128 </td></tr><tr><td>片</td><td> 99 </td></tr><tr><td>体素的大小</td><td> 0.4×0.4×0.6毫米</td></tr><tr><td>动态帧</td><td> 12×300秒</td></tr><tr><td>重建类型</td><td> OS-MLEM（6子集，6次迭代） </td></tr></tbody></table> 表1. MRI脉冲序列参数在协议中所述的扫描和PET采集，直方图和重建参数。

Watch this Scientific Journal Video about Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia at JoVE.com

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

这里介绍的方法使用同时正电子发射断层扫描和磁共振成像。在脑缺氧缺血模型，扩散和糖代谢的动态变化过程及伤后发生。在这个模型中不断变化和不可重复的损害就必须同时获得，如果有意义的多模态成像的数据是被收购。

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 ...

simultaneous-petmri-imaging-during-mouse-cerebral-hypoxia-ischemia

Universidad San Sebastian

Research

JoVE Journal

Medicine

12.2K 次观看.  University of California, Davis. 这里介绍的方法使用同时正电子发射断层扫描和磁共振成像。在脑缺氧缺血模型，扩散和糖代谢的动态变化过程及伤后发生。在这个模型中不断变化和不可重复的损害就必须同时获得，如果有意义的多模态成像的数据是被收购。 

视频: Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

Simultaneous fMRI and Electrophysiology in the Rodent Brain

To examine the neural basis of the blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) signal, we have developed a rodent model in which functional MRI data and in vivo intracortical recording can be performed simultaneously. The combination of MRI and electrical recording is technically challenging because the electrodes used for recording distort the MRI images and the MRI acquisition induces noise in the electrical recording. To minimize the mutual interference of the two modalities, glass microelectrodes were used rather than metal and a noise removal algorithm was implemented for the electrophysiology data. In our studies, two microelectrodes were separately implanted in bilateral primary somatosensory cortices (SI) of the rat and fixed in place. One coronal slice covering the electrode tips was selected for functional MRI. Electrode shafts and fixation positions were not included in the image slice to avoid imaging artifacts. The removed scalp was replaced with toothpaste to reduce susceptibility mismatch and prevent Gibbs ringing artifacts in the images. The artifact structure induced in the electrical recordings by the rapidly-switching magnetic fields during image acquisition was characterized by averaging all cycles of scans for each run. The noise structure during imaging was then subtracted from original recordings. The denoised time courses were then used for further analysis in combination with the fMRI data. As an example, the simultaneous acquisition was used to determine the relationship between spontaneous fMRI BOLD signals and band-limited intracortical electrical activity. Simultaneous fMRI and electrophysiological recording in the rodent will provide a platform for many exciting applications in neuroscience in addition to elucidating the relationship between the fMRI BOLD signal and neuronal activity.

We have developed a method for simultaneous functional magnetic resonance imaging and electrophysiological recording in the rodent brain, providing a platform for the investigation of the relationship between neural activity and the blood oxygenation level dependent (BOLD) MRI signal.

同时在啮齿动物脑功能磁共振成像和电

To examine the neural basis of the blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) signal, we have developed a rodent model in ...

科研

神经科学

Multiple-mouse Neuroanatomical Magnetic Resonance Imaging

The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and evaluating mouse models of human disease. MRI is an excellent modality for investigating genetically altered animals. It is capable of whole brain coverage, can be used in vivo, and provides multiple contrast mechanisms for investigating different aspects of neuranatomy and physiology. The advent of high-field scanners along with the ability to scan multiple mice simultaneously allows for rapid phenotyping of novel mutations.
Effective mouse MRI studies require attention to many aspects of experiment design. In this article, we will describe general methods to acquire quality images for mouse phenotyping using a system that images mice concurrently in shielded transmit/receive radio frequency (RF) coils in a common magnet (Bock et al., 2003). We focus particularly on anatomical phenotyping, an important and accessible application that has shown a high potential for impact in many mouse models at our imaging centre. Before we can provide the detailed steps to acquire such images, there are important practical considerations for both in vivo brain imaging (Dazai et al., 2004) and ex vivo brain imaging (Spring et al., 2007) that should be noted. These are discussed below.

Magnetic resonance imaging (MRI) has become an increasingly popular tool for examining the phenotype of genetically altered mice. This article illustrates the methods necessary to achieve high-throughput phenotyping of genetically altered mice using multiple-mouse MRI.

多鼠神经解剖学磁共振成像

The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and ...

Detection of Microregional Hypoxia in Mouse Cerebral Cortex by Two-photon Imaging of Endogenous NADH Fluorescence

The brain's ability to function at high levels of metabolic demand depends on continuous oxygen supply through blood flow and tissue oxygen diffusion. Here we present a visualized experimental and methodological protocol to directly visualize microregional tissue hypoxia and to infer perivascular oxygen gradients in the mouse cortex. It is based on the non-linear relationship between nicotinamide adenine dinucleotide (NADH) endogenous fluorescence intensity and oxygen partial pressure in the tissue, where observed tissue NADH fluorescence abruptly increases at tissue oxygen levels below 10 mmHg1. We use two-photon excitation at 740 nm which allows for concurrent excitation of intrinsic NADH tissue fluorescence and blood plasma contrasted with Texas-Red dextran. The advantages of this method over existing approaches include the following: it takes advantage of an intrinsic tissue signal and can be performed using standard two-photon in vivo imaging equipment; it permits continuous monitoring in the whole field of view with a depth resolution of ~50 &mu;m. We demonstrate that brain tissue areas furthest from cerebral blood vessels correspond to vulnerable watershed areas which are the first to become functionally hypoxic following a decline in vascular oxygen supply. This method allows one to image microregional cortical oxygenation and is therefore useful for examining the role of inadequate or restricted tissue oxygen supply in neurovascular diseases and stroke.

Here we describe a method to directly visualize microregional tissue hypoxia in the mouse cortex in vivo. It is based on concurrent two-photon imaging of nicotinamide adenine dinucleotide (NADH) and the cortical microcirculation. This method is useful for high resolution analysis of tissue oxygen supply.

检测内源NADH的荧光双光子成像的小鼠大脑皮层Microregional缺氧

The brain's ability to function at high levels of metabolic demand depends on continuous oxygen supply through blood flow and tissue oxygen diffusion. ...

MRI and PET in Mouse Models of Myocardial Infarction

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ideal model for testing novel therapeutic strategies.
In vivo magnetic resonance imaging (MRI) gives excellent views of the heart noninvasively with clear anatomical detail, which can be used for accurate functional assessment. Contrast agents can provide basic measures of tissue viability but these are nonspecific. Positron emission tomography (PET) is a complementary technique that is highly specific for molecular imaging, but lacks the anatomical detail of MRI. Used together, these techniques offer a sensitive, specific and quantitative tool for the assessment of the heart in disease and recovery following treatment.
In this paper we explain how these methods are carried out in mouse models of acute myocardial infarction. The procedures described here were designed for the assessment of putative protective drug treatments. We used MRI to measure systolic function and infarct size with late gadolinium enhancement, and PET with fluorodeoxyglucose (FDG) to assess metabolic function in the infarcted region. The paper focuses on practical aspects such as slice planning, accurate gating, drug delivery, segmentation of images, and multimodal coregistration. The methods presented here achieve good repeatability and accuracy maintaining a high throughput.

We describe how to perform MRI and PET imaging of the mouse heart. The protocol is tailored to assess treatment efficacy in models of myocardial infarction and heart failure.

MRI和PET心肌梗死小鼠模型

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ...

医学

Non-Invasive PET/MR Imaging in an Orthotopic Mouse Model of Hepatocellular Carcinoma

Preclinical experimental models of hepatocellular carcinoma (HCC) that recapitulate human disease represent an important tool to study tumorigenesis and evaluate novel therapeutic approaches. Non-invasive whole-body imaging using positron emission tomography (PET) provides critical insights into the in vivo characteristics of tissues at the molecular level in real-time. We present here a protocol for orthotopic HCC xenograft creation with and without hepatic artery ligation (HAL) to induce tumor hypoxia and the assessment of their tumor metabolism in vivo using [18F]Fluoromisonidazole ([18F]FMISO) and [18F]Fluorodeoxyglucose ([18F]FDG) PET/magnetic resonance (MR) imaging. Tumor hypoxia could be readily visualized using the hypoxia marker [18F]FMISO, and it was found that the [18F]FMISO uptake was higher in HCC mice that underwent HAL than in the non-HAL group, whereas [18F]FDG could not distinguish tumor hypoxia between the two groups. HAL tumors also displayed a higher level of hypoxia-inducible factor (HIF)-1&#945; expression in response to hypoxia. Quantification of HAL tumors showed a 2.3-fold increase in [18F]FMISO uptake based on the standardized value uptake (SUV) approach.

Here, we present a protocol to create orthotopic hepatocellular carcinoma xenografts with and without hepatic artery ligation and perform non-invasive positron emission tomography (PET) imaging of tumor hypoxia using [18F]Fluoromisonidazole ([18F]FMISO) and [18F]Fluorodeoxyglucose ([18F]FDG).

肝细胞癌原位小鼠模型中的无创PET/MR成像

Preclinical experimental models of hepatocellular carcinoma (HCC) that recapitulate human disease represent an important tool to study tumorigenesis and ...

癌症研究

A Dual Tracer PET-MRI Protocol for the Quantitative Measure of Regional Brain Energy Substrates Uptake in the Rat

We present a method for comparing the uptake of the brain&#39;s two key energy substrates: glucose and ketones (acetoacetate [AcAc] in this case) in the rat. The developed method is a small-animal positron emission tomography (PET) protocol, in which&#160;11C-AcAc and 18F-fluorodeoxyglucose (18F-FDG) are injected sequentially in each animal. This dual tracer PET acquisition is possible because of the short half-life of 11C (20.4 min). The rats also undergo a magnetic resonance imaging (MRI) acquisition seven days before the PET protocol. Prior to image analysis, PET and MRI images are coregistered to allow the measurement of regional cerebral uptake (cortex, hippocampus, striatum, and cerebellum). A quantitative measure of 11C-AcAc and 18F-FDG brain uptake (cerebral metabolic rate; &#956;mol/100 g/min) is determined by kinetic modeling using the image-derived input function (IDIF) method. Our new dual tracer PET protocol is robust and flexible; the two tracers used can be replaced by different radiotracers to evaluate other processes in the brain. Moreover, our protocol is applicable to the study of brain fuel supply in multiple conditions such as normal aging and neurodegenerative pathologies such as Alzheimer&#39;s and Parkinson&#39;s diseases.

Small-animal positron emission tomography enables the assessment of the brain&#39;s two main energy substrates:&#160;glucose and ketones. In the present method, 11C-acetoacetate and 18F-fluorodeoxyglucose are injected sequentially in each animal, and their uptake is measured quantitatively in specific brain regions determined from the magnetic resonance images.

We present a method for comparing the uptake of the brain&#39;s two key energy substrates: glucose and ketones (acetoacetate [AcAc] in this case) in the ...

Noninvasive In Vivo Small Animal MRI and MRS: Basic Experimental Procedures

Small animal Magnetic Resonance (MR) research has emerged as an important element of modern biomedical research due to its non-invasive nature and the richness of biological information it provides. MR does not require any ionizing radiation and can noninvasively provide higher resolution and better signal-to-noise ratio in comparison to other tomographic or spectroscopic modalities. In this protocol, we will focus on small animal MR imaging and MR spectroscopy (MRI/MRS) to noninvasively acquire relaxation weighted 1H images of mouse and to obtain 31P spectra of mouse muscle. This work does not attempt to cover every aspect of small animal MRI/MRS but rather introduces basic procedures of mouse MRI/MRS experiments. The main goal of this work is to inform researchers of the basic procedures for in vivo MR experiments on small animals. The goal is to provide a better understanding of basic experimental procedures to allow researchers new to the MR field to better plan for non-MR components of their studies so that both MR and non-MR procedures are seamlessly integrated.

Noninvasive In Vivo Small Animal MRI and MRS: Basic Experimental Procedures

This work describes basic procedures of noninvasive small animal MRI and MRS in vivo.

无创在体内小动物的MRI和MRS：基本实验程序

Small animal Magnetic Resonance (MR) research has emerged as an important element of modern biomedical research due to its non-invasive nature and the ...

生物学

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to return to normal in a large majority of patients2, which is mainly due to current lack of clinical treatment for acute stroke. This necessitates understanding the physiological effects of cerebral ischemia on brain tissue over time and is a major area of active research. Towards this end, experimental progress has been made using rats as a preclinical model for stroke, particularly, using non-invasive methods such as 18F-fluorodeoxyglucose (FDG) coupled with Positron Emission Tomography (PET) imaging3,10,17. Here we present a strategy for inducing cerebral ischemia in rats by middle cerebral artery occlusion (MCAO) that mimics focal cerebral ischemia in humans, and imaging its effects over 24 hr using FDG-PET coupled with X-ray computed tomography (CT) with an Albira PET-CT instrument. A VOI template atlas was subsequently fused to the cerebral rat data to enable a unbiased analysis of the brain and its sub-regions4. In addition, a method for 3D visualization of the FDG-PET-CT time course is presented. In summary, we present a detailed protocol for initiating, quantifying, and visualizing an induced ischemic stroke event in a living Sprague-Dawley rat in three dimensions using FDG-PET.

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Brain damage resulting from cerebral ischemia may be non-invasively imaged and studied in rats using pre-clinical positron emission tomography coupled with the injectable radioactive probe, 18F-fluorodeoxyglucose. Further, the use of modern software tools that include volume of interest (VOI) brain templates dramatically increase the quantitative information gleaned from these studies.

无创成像和脑缺血分析生活中的大鼠使用正电子发射断层扫描<sup&gt; 18</sup&gt; F-FDG

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to ...

A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat model of ischemic stroke, differences in quantitative T1 and T2 MRI relaxation times (qT1 and qT2) between the ischemic lesion (delineated by low diffusion) and the contralateral non-ischemic hemisphere increase with time from stroke onset. The time dependency of MRI relaxation time differences is heuristically described by a linear function and thus provides a simple estimate of stroke onset time. Additionally, the volumes of abnormal qT1 and qT2 within the ischemic lesion increase linearly with time providing a complementary method for stroke timing. A (semi)automated computer routine based on the quantified diffusion coefficient is presented to delineate acute ischemic stroke tissue in rat ischemia. This routine also determines hemispheric differences in qT1 and qT2 relaxation times and the location and volume of abnormal qT1 and qT2 voxels within the lesion. Uncertainties associated with onset time estimates of qT1 and qT2 MRI data vary from &plusmn; 25 min to &plusmn; 47 min for the first 5 hours of stroke. The most accurate onset time estimates can be obtained by quantifying the volume of overlapping abnormal qT1 and qT2 lesion volumes, termed 'Voverlap' (&plusmn; 25 min) or by quantifying hemispheric differences in qT2 relaxation times only (&plusmn; 28 min). Overall, qT2 derived parameters outperform those from qT1. The current MRI protocol is tested in the hyperacute phase of a permanent focal ischemia model, which may not be applicable to transient focal brain ischemia.

A protocol for stroke onset time estimation in a rat model of stroke exploiting quantitative magnetic resonance imaging (qMRI) parameters is described. The procedure exploits diffusion MRI for delineation of the acute stroke lesion and quantitative T1 and T2 (qT1 and qT2) relaxation times for timing of stroke.

脑缺血中风发作时间估计的磁共振成像协议

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat ...

PET Imaging of Neuroinflammation Using [11C]DPA-713 in a Mouse Model of Ischemic Stroke

Neuroinflammation is central to the pathological cascade following ischemic stroke. Non-invasive molecular imaging methods have the potential to provide critical insights into the temporal dynamics and role of certain neuroimmune interactions in stroke. Specifically, Positron Emission Tomography (PET) imaging of translocator protein 18 kDa (TSPO), a marker of activated microglia and peripheral myeloid-lineage cells, provides a means to detect and track neuroinflammation in vivo. Here, we present a method to accurately quantify neuroinflammation using [11C]N,N-Diethyl-2-[2-(4-methoxyphenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl]acetamide ([11C]DPA-713), a promising second generation TSPO-PET radiotracer, in distal middle cerebral artery occlusion (dMCAO) compared to sham-operated mice. MRI was performed 2 days post-dMCAO surgery to confirm stroke and define the infarct location and volume. PET/Computed Tomography (CT) imaging was carried out 6 days post-dMCAO to capture the peak increase in TSPO levels following stroke. Quantitation of PET images was conducted to assess the uptake of [11C]DPA-713 in the brain and spleen of dMCAO and sham mice to assess central and peripheral levels of inflammation. In vivo [11C]DPA-713 brain uptake was confirmed using ex vivo autoradiography.

PET Imaging of Neuroinflammation Using [11C]DPA-713 in a Mouse Model of Ischemic Stroke

Positron Emission Tomography (PET) imaging of translocator protein 18 kDa (TSPO) provides a non-invasive means to visualize the dynamic role of neuroinflammation in the development and progression of brain diseases. This protocol describes TSPO-PET and ex vivo autoradiography to detect neuroinflammation in a mouse model of ischemic stroke.

Neuroinflammation 的 PET 成像 [11C] DPA-713 在小鼠缺血性中风模型中的应用

Neuroinflammation is central to the pathological cascade following ischemic stroke. Non-invasive molecular imaging methods have the potential to provide ...

同时PET / MRI成像在小鼠脑缺氧缺血

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