Core--Mouse MR imaging

随着研究心脏生理学和病理生理学的小鼠模型的出现，强烈需要小鼠心脏的磁共振成像（MRI）。该核心的目标是为测量小鼠的心脏功能和灌注提供资源。由于目前MRI设备的成本很高，每个项目都无法获得自己的仪器，因此需要核心资源。此外，核心服务确保在一个项目中对一组动物进行成像所获得的经验将应用于所有项目。我们的研究小组是最早在大鼠中展示心脏成像的小组之一。然而，在对小鼠心脏进行成像时，需要进行几项修改，主要是由于动物的体型较小（需要更好的ECG采集和更高的图像分辨率）以及影响门控成像序列和收缩期和舒张期相对时间的更快心率。因此，我们已经实施并证明了几个修改的效用：一个专门的3cm直径的接收仅表面射频线圈被分接到一个有机玻璃板的底部，三个箔板连接到心电图线。将两个前鼠爪和一个后鼠爪用胶带粘在箔上。其中几个是这样建造的，一个动物可以定位和稳定，而第一个正在成像。对于新生小鼠成像，在前爪和后爪的任一侧上构建具有ECG板的螺线管线圈。在心脏收缩期和舒张期获得了高质量的多层图像，心脏质量的MR测量值与尸检测量值之间存在良好的相关性（r=0.97）。获得舒张期和收缩期图像，并计算射血分数。核心研究的一般方法将遵循先前用于小动物心脏MRI研究的方法。将获得冠状面定位，并根据其规定短轴视图。将在8个不同时间点获得覆盖整个心脏的多切片系列图像，以覆盖整个心动周期的心脏。根据这些数据集，将计算心脏质量和舒张末期/收缩末期容积，并从中推导射血分数。为了获得心肌的灌注加权图像，将在Gd-DTPA团注通过期间获得T1加权图像。此外，将实施磁化准备灌注成像。

With the advent of mouse models to investigate cardiac physiology and pathophysiology, there is a strong need for magnetic resonance imaging (MRI) of mouse hearts. The goal of this Core is to provide a resource for measurement of cardiac function and perfusion in mice. A Core Resource is needed due to the current high cost of an MRI unit which precludes each project from obtaining its own instrumentation. In addition, A core service ensures that the experience gained from imaging one set of animals in one project will be applied to all projects. Our group was one of the first to demonstrate cardiac imaging in rats. However, there are several modifications which need to be addressed when imaging mouse hearts, due mainly to the small size of the animals (requiring better ECG acquisitions and higher image resolution) and the faster heart rates which affect the gated imaging sequences and the relative time of systole and diastole. Therefore, we have implemented and demonstrated the utility of several modifications: A specialized 3 cm diameter receive only surface radio-frequency coil was tapped onto the bottom of a plexiglass plate with three foil plates connected to ECG wires. The two front mouse paws and one back paw were taped onto the foil. Several of these were built such that one animal could be positioned and stabilized while the first was being imaged. For neonatal mouse imaging, a solenoid coil was build with ECG plates on either side for the front and back paws. High quality multi-slice images were obtained at systole and diastole, excellent correlation (r=0.97) was found between MR measurements of heart mass and mass determined at autopsy. Both diastolic and systolic images were obtained, from which ejection fractions were computed. The general methodology for the Core will flow that used previously for cardiac MRI studies in small animals. A coronal scout will be obtained from which short axis views will be prescribed. A multi-slice series of images will be obtained to cover the entire heart at 8 different time points in order to cover the heart through the cardiac cycle. From these data sets, cardiac mass, and end-diastolic/end-systolic volumes will be computed, from which ejection fractions will be derived. In order to obtain perfusion- weighted images of the myocardium, T1 weighted images will be obtained during the passage of a bolus of Gd-DTPA. In addition, magnetization prepared perfusion imaging will be implemented.