Hollender Peter, Bradway David, Wolf Patrick, Goswami Robi, Trahey Gregg
IEEE Trans Ultrason Ferroelectr Freq Control. 2013 Aug;60(8):1669-82. doi: 10.1109/TUFFC.2013.2749.
Four pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with focused acoustic radiation force (ARF) impulses and image the subsequent tissue response. Tissue displacement in response to the ARF excitation was calculated with a phase-based estimator, and transverse wave magnitude and velocity were each estimated at every depth. The excitation sequence was repeated rapidly, either in the same location to generate 40 Hz M-modes at a single steering angle, or with a modulated steering angle to synthesize 2-D displacement magnitude and shear wave velocity images at 17 points in the cardiac cycle. Both types of images were acquired from various views in the right and left ventricles, in and out of infarcted regions. In all animals, acoustic radiation force impulse (ARFI) and shear wave elasticity imaging (SWEI) estimates indicated diastolic relaxation and systolic contraction in noninfarcted tissues. The M-mode sequences showed high beat-to-beat spatio-temporal repeatability of the measurements for each imaging plane. In views of noninfarcted tissue in the diseased animals, no significant elastic remodeling was indicated when compared with the control. Where available, views of infarcted tissue were compared with similar views from the control animal. In views of the LVFW, the infarcted tissue presented as stiff and non-contractile compared with the control. In a view of the IVS, no significant difference was seen between infarcted and healthy tissue, whereas in another view, a heterogeneous infarction was seen to be presenting itself as non-contractile in systole.
四只猪，其中三只在室间隔心尖部（IVS）和/或左心室游离壁（LVFW）有局灶性梗死，用心脏内超声心动图（ICE）换能器进行成像。使用定制的波束序列，通过聚焦声辐射力（ARF）脉冲激发心肌，并对随后的组织反应进行成像。使用基于相位的估计器计算响应ARF激发的组织位移，并在每个深度估计横向波幅度和速度。激发序列快速重复，要么在同一位置以单个转向角生成40Hz的M型模式，要么以调制的转向角合成心动周期中17个点的二维位移幅度和剪切波速度图像。两种类型的图像均从右心室和左心室的各个视图中获取，包括梗死区域内外。在所有动物中，声辐射力脉冲（ARFI）和剪切波弹性成像（SWEI）估计表明非梗死组织存在舒张期松弛和收缩期收缩。M型序列显示每个成像平面测量的逐搏时空重复性很高。在患病动物的非梗死组织视图中，与对照组相比，未显示出明显的弹性重塑。在可行的情况下，将梗死组织的视图与对照动物的类似视图进行比较。在LVFW视图中，与对照组相比，梗死组织表现为僵硬且无收缩性。在IVS的一个视图中，梗死组织与健康组织之间未观察到显著差异，而在另一个视图中，可见异质性梗死在收缩期表现为无收缩性。
