Azhari H, Weiss J L, Shapiro E P
Julius Silver Institute, Department of Biomedical Engineering, Technion-IIT, Haifa, Israel.
Adv Exp Med Biol. 1995;382:319-28. doi: 10.1007/978-1-4615-1893-8_31.
Quantification of myocardial strains is essential for understanding cardiac mechanics. Previous techniques for assessing regional myocardial strains have been mainly limited to invasive procedures. A technique by which tagging can be added to magnetic resonance images (MRI) has recently been introduced and allows for noninvasive measurement of myocardial deformations. We have applied MRI tagging to two sets of orthogonal planes and have obtained three dimensional (3D) reconstructions of 24 myocardial cuboids at end-diastole (ED) and at end-systole (ES). Applying finite strain analysis to these cuboids we were able to study the longitudinal distribution of the endocardial and epicardial principal strains (PS) in the normal canine heart. In addition we have calculated the longitudinal distribution of the left ventricular (LV) transmural thickening using a 3D approach. Our results show similarity in the longitudinal distribution of endocardial PS and transmural thickening. These results imply that endocardial strains are determined not only by endocardial fiber deformations but mainly by geometrical coupling through transmural thickening.
心肌应变的量化对于理解心脏力学至关重要。以往评估局部心肌应变的技术主要局限于侵入性操作。最近引入了一种可在磁共振成像（MRI）中添加标记的技术，该技术可实现心肌变形的无创测量。我们已将MRI标记应用于两组正交平面，并获得了舒张末期（ED）和收缩末期（ES）24个心肌长方体的三维（3D）重建图像。对这些长方体应用有限应变分析，我们能够研究正常犬心内膜和心外膜主应变（PS）的纵向分布。此外，我们还使用三维方法计算了左心室（LV）跨壁增厚的纵向分布。我们的结果显示心内膜PS和跨壁增厚的纵向分布相似。这些结果表明，心内膜应变不仅由心内膜纤维变形决定，主要还由跨壁增厚的几何耦合决定。
