Theoretical quality assessment of myocardial elastography with in vivo validation
Theoretical quality assessment of myocardial elastography with in vivo validation
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DOI：
10.1109/tuffc.2007.528
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发表时间：
2007-11-01
影响因子：
3.6
通讯作者：
Konofagou, Elisa E.
中科院分区：
文献类型：
--
作者：
Lee, Wei-Ning;Ingrassia, Christopher M.;Konofagou, Elisa E.
心肌弹性成像（ME）是一种基于射频（RF）的散斑跟踪技术，在二维搜索中采用一维（I-D）相互关联和新的相关方法来估计和充分成像二维跨壁变形场，并检测异常心功能。为了评估基于先前开发的犬左心室三维有限元模型的二维心肌弹性成像的性能，首先开发了一个理论框架。考虑了正常（对照）和缺血（左旋，LCx）模型，它们比运动学模型更完整地代表心肌变形。首先使用二维卷积图像形成模型生成射频信号，用于正常和缺血情况下ME的质量评估。进一步建立了三维图像形成模型，研究了平面外运动对二维平面内运动估计的影响。迭代估计连续射频帧之间的正交平面内位移分量（即横向和轴向）。然后将所有从舒张末期（ED）到收缩末期（ES）的增量二维位移累积起来，得到累积二维位移，并将其进一步用于计算累积二维收缩有限应变。此外，从二维有限应变分量中获得与角度和帧率无关的累积收缩径向和周向应变，并在全视图下成像以检测缺血区域。我们还探索了我们的技术在准确描述疾病方面的局限性的理论理解，并在正常人类心肌的2-D短轴（SA）超声心动图视图中，通过标记磁共振成像（tMRI）在体内验证了它。该理论框架成功地证明了二维心肌弹性成像技术是一种可靠的工具，可以完整地估计和描述平面内心肌变形场，以及使用已建立的有限元左心室犬模型准确识别病理力学功能。在一项初步研究中，二维心肌弹性成像被证明能够在临床环境中成像心肌变形，与等效的tMRI估计相当。
Myocardial elastography (ME), a radio frequency (RF)-based speckle tracking technique with onedimensional (I-D) cross correlation and novel recorrelation methods in a 2-D search was proposed to estimate and fully image 2-D transmural deformation field and to detect abnormal cardiac function. A theoretical framework was first developed in order to evaluate the performance of 2-D myocardial elastography based on a previously developed 3D finite-element model of the canine left ventricle. A normal (control) and an ischemic (left-circumflex, LCx) model, which more completely represented myocardial deformation than a kinematic model, were considered. A 2-D convolutionalimage formation model was first used to generate RF signals for quality assessment of ME in the normal and ischemic cases. A 3-D image formation model was further developed to investigate the effect of the out-of-plane motion on the 2-D, in-plane motion estimation. Both orthogonal, in-plane displacement components (i.e., lateral and axial) between consecutive RF frames were iteratively estimated. All the estimated incremental 2-D displacements from end-diastole (ED) to end-systole (ES) were then accumulated to acquire the cumulative 2-D displacements, which were further used to calculate the cumulative 2-D systolic finite strains. Furthermore, the cumulative systolic radial and circumferential strains, which were angle- and frame-rate independent, were obtained from the 2-D finite-strain components and imaged in full view to detect the ischemic region. We also explored the theoretical understanding of the limitations of our technique for the accurate depiction of disease and validated it in vivo against tagged magnetic resonance imaging (tMRI) in the case of a normal human myocardium in a 2-D short-axis (SA) echocardiographic view. The theoretical framework succeeded in demonstrating that the 2-D myocardial elastography technique was a reliable tool for the complete estimation and depiction of the in-plane myocardial deformation field as well as for accurate identification of pathological mechanical function using established finite-element, left-ventricular canine models. In a preliminary study, the 2-D myocardial elastography was shown capable of imaging myocardial deformation comparable to equivalent tMRI estimates in a clinical setting.