论文标题
具有三维全波非线性声学模拟的超声成像。第2部分：肋间成像中图像降解的来源
Ultrasound imaging with three dimensional full-wave nonlinear acoustic simulations. Part 2: sources of image degradation in intercostal imaging
论文作者
论文摘要
全波模拟应用于肋间成像方案，以确定相对于像差和混响的基本和谐波图像退化的来源。这些仿真基于这两部分论文的第一部分，该纸张建立了全波模拟方法，以直接基于人体波传播的第一个原理生成逼真的超声图像。 Ultasound图像是基于传播和反射的第一原理生成的，它们描述了分布式畸变和混响混乱之间的相互作用。在计算机中研究了三种在体内无法实现的成像场景。首先，将肋骨完全取出并用脂肪代替。然后，将肋骨保持在解剖上正确的配置中，以产生参考图像。最后，肋骨在海拔中更靠近。基于传播的B模式图像显示，在这三种情况下，第二种，解剖上正确的配置具有最佳的对比度比率。这是由于两个竞争效果。首先，肋骨有效地将基本和谐波光束置于3-5 dB。仅此效果就可以预测图像质量的改善。但是，B模式图像质量以对比度与噪声比率降低了8％。为了解释这些变化，结果表明，必须考虑第二个效果，多重混响。点扩散函数分析表明，当肋骨更靠近时，它们会产生更多的回响混乱（2.4至2.9 dB），即使Beamplot的侧球较低，也会降低图像质量。因此，在这种肋间成像方案中，肋骨对梁的形状和混响的影响在图像质量方面竞争，并且有一个最佳的声学窗口可以平衡它们。
Fullwave simulations are applied to an intercostal imaging scenario to determine the sources of fundamental and harmonic image degradation with respect to aberration and reverberation. These simulations are based on Part I of this two part paper, which established the Fullwave simulation methods to generate realistic ultrasound images based directly on the first principles of wave propagation in the human body. The ultasound images are generated based on the first principles of propagation and reflection and they describe interplay between distributed aberration and reverberation clutter. Three imaging scenarios that would not be realizable in vivo are investigated in silico. First, the ribs were completely removed and replaced with fat. Then, the ribs were maintained in their anatomically correct configuration to yield a reference image. Finally the ribs were placed closer together in elevation. The propagation based B-mode images show that of these three scenarios the second, anatomically correct configuration, has the best contrast-to-noise ratio. This is due to two competing effects. First the ribs effectively apodize the fundamental and harmonic beams by 3-5 dB. This effect alone would predict an improvement in image quality. However, the B-mode image quality, measured by the contrast-to-noise ratio degrades by 8%. To explain these changes, it is shown that a second effect, multiple reverberation, must be taken into account. A point spread function analysis shows that when the ribs are placed closer together they generate significantly more reverberation clutter (by 2.4 to 2.9 dB), degrading the image quality even though the beamplot has lower sidelobes. In this intercostal imaging scenario the effects of the ribs on beam shape and reverberation are therefore in competition in terms of image quality and there is an optimal acoustic window that balances them out.
