QUANTIFICATION OF MYOCARDIAL FUNCTION IN 3 DIMENSIONS

心肌应力应变的临床和实验应用 收缩和舒张期心脏功能的描述尚待准确 活体双室心的三维描述 几何图形。心电门控磁成像的解剖三维重建 心脏的磁共振成像(MRI)与其他3-D扫描方式不同， 能够清楚地描绘出血液/腔壁的界面 完好无损的动物。真实的三维几何描述，包括墙 厚度，因此可以通过非侵入性扫描而无需 注射造影剂。这项提议的目标是将这一点结合起来 使用腔室压力测定的方式，以允许应用 双室心功能的应力应变描述符。 第一阶段(验证和开发)包括比较心肌 由心电门控三维磁共振成像获得的完整的、 麻醉狗(1)随后对切除的心脏进行扫描，(2) 标准定量对比脑室造影术；(3)尸检 在相同的动物身上的决定。一种特别设计的校准 Phantom将允许验证3-D MRI测量。的描述 由三维心脏MRI扫描提供的双室心脏几何形状将 然后与同时获得的腔室压力数据进行接口 用于应用收缩和舒张期指数的相同动物 功能。 第二阶段(实验室应用将涉及使用3-D心脏磁共振 双室三维负荷时心脏几何构型的评估 分析。这将包括使用有限元方法以及 目前使用的标准模型采用收缩(收缩末期)和 舒张期应力应变分析。双心室的守恒性 室壁应力将通过全球3-D图形显示来评估 在整个双心室几何模型上的应力测定 由3-D MRI重建提供。对完整、正常犬种的研究 血液循环将与急性和慢性疾病动物的血液循环进行比较。 慢性同侧室壁应力改变。后续 对侧室壁的应力位移将是 评估除澄清间隔调解在以下方面的作用 这种能量转移。对这些双室的进一步定义 应力-应变关系可能会挑战或至少进一步定义我们的 对心脏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.