QUANTIFICATION OF MYOCARDIAL FUNCTION IN 3 DIMENSIONS

心肌应力应变的临床与实验应用 收缩和舒张心室功能的描述尚待准确 体内双心室心脏的三维（3-D）描述 几何心电门控磁共振解剖三维重建 心脏的共振成像（MRI），与其他3-D扫描模式不同， 能够清楚地描绘血液/腔室壁界面， 完整的动物真实的三维几何描述，包括墙 因此，通过无创扫描可获得厚度， 注射造影剂。本提案的目标是将此 具有腔室压力测定的模态，以允许应用 双心室心功能的应力-应变描述符。 第一阶段（验证和开发）涉及比较心肌 通过ECG门控3-D MRI获得的完整、 麻醉犬，（1）随后扫描切除的心脏，（2） 标准定量对比心室造影，和（3）尸检 在相同的动物中进行测定。专门设计的校准 体模将允许确认3-D MRI测量。的描述 3D心脏MRI扫描提供的双心室心脏几何形状将 然后与同时获得的室压力数据接口， 用于应用收缩和舒张指数的相同动物 功能 第二阶段（实验室应用将涉及使用三维心脏MRI 评估心脏几何结构以执行双心室3-D应力 分析.这将包括使用有限元法，以及 目前使用的标准模型采用收缩期（收缩末期）和 舒张期应力-应变分析。双心室守恒 将通过全局三维图形显示评估心室壁应力 整个双心室几何模型的应力测定 由3D核磁共振成像重建提供。在完整、正常犬中的研究 循环将与急性和慢性炎症动物的循环进行比较， 慢性同侧心室壁应力改变。后续 对侧心室壁的应力位移将 除了澄清间隔调解的作用外， 这种能量转移这些双心室的进一步定义 应力-应变关系可能会挑战或至少进一步定义我们的 对心室相互作用有基本的了解。

The clinical and experimental application of myocardial stress-strain descriptors of systolic and diastolic ventricular function awaits accurate three-dimensional (3-D) description of IN VIVO biventricular cardiac geometry. Anatomic three-dimensional reconstruction by ECG-gated magnetic resonance imaging (MRI) of the heart, unlike other 3-D scanning modalities, is capable of clearly delineating the blood/chamber wall interface in intact animals. A true 3-D geometrical description, including wall thickness, has therefore become available by NON-INVASIVE scanning without infusion of contrast agents. The goal of this proposal is to interface this modality with chamber pressure determinations to allow the application of stress-strain descriptors of biventricular cardiac function. Phase I (validation and development) involves the comparison of myocardial dimensional descriptions obtained by ECG-gated 3-D MRI in intact, anesthetized dogs with (1) subsequent scans of the excised hearts, (2) standard quantitative contrast ventriculography, and (3) necropsy determinations in the same animals. A specially designed calibration phantom will allow validation of 3-D MRI measurements. The description of biventricular cardiac geometry supplied by 3-D cardiac MRI scanning will then be interfaced with chamber pressure data obtained simultaneously in the same animals for application of indices of systolic and diastolic function. Phase II (laboratory application will involve the use of 3-D cardiac MRI assessment of cardiac geometry to perform biventricular 3-D stress analysis. This will include use of the finite-element method, as well as currently used standard models employing systolic (end-systolic) and diastolic stress-strain analyses. The biventricular conservation of ventricular wall stress will be assessed by graphic display of global 3-D stress determinations over the entire biventricular geometrical model supplied by 3-D MRI reconstruction. Studies in the intact, normal canine circulation will be compared with those in animals with both acute and chronic ipsilateral alteration of ventricular wall stress. Subsequent stress displacement to the contralateral ventricular chamber walls will be assessed in addition to clarification of the role of septal mediation in this energy transference. Further definition of these biventricular stress-strain relationships may challenge, or at least further define, our basic understanding of ventricular interaction.