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，迫切需要对小鼠心脏进行磁共振成像(MRI)。这个核心的目标是提供一种测量小鼠心脏功能和血流灌注的资源。由于目前核磁共振成像仪的费用很高，每个项目都无法获得自己的仪器，因此需要一项核心资源。此外，核心服务确保在一个项目中为一组动物成像所获得的经验将应用于所有项目。我们小组是第一批在大鼠身上展示心脏成像的小组之一。然而，在为小鼠心脏成像时，有几个修改需要解决，主要是因为动物较小(需要更好的心电采集和更高的图像分辨率)和较快的心率，这会影响门控成像序列和收缩和舒张期的相对时间。因此，我们已经实施并演示了几种改进的用途：在有机玻璃平板的底部安装了一个专门的直径为3厘米的仅接收表面射频线圈，并将三块箔板连接到心电图线上。两只前爪和一只后爪被绑在锡箔上。其中几个是这样建造的，即当第一只动物被成像时，一只动物可以被定位和稳定。为了对新生小鼠进行成像，建立了一个螺线管线圈，两侧都有用于前爪和后爪的心电图板。在心脏收缩和舒张期获得了高质量的多层螺旋图像，心脏质量的MR测量值与尸检确定的质量之间有很好的相关性(r=0.97)。同时获得舒张期和收缩期图像，从中计算射血分数。Core的一般方法将采用以前用于小动物心脏核磁共振研究的方法。将获得一个冠状侦察机，从中指定短轴视图。将获得一系列多层图像，在8个不同的时间点覆盖整个心脏，以覆盖整个心脏周期。根据这些数据集，将计算心脏质量和舒张末/收缩末期容量，从中得出射血分数。为了获得心肌的灌注加权图像，在注射Gd-DTPA的过程中将获得T1加权图像。此外，还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.