Graduate School of Science and Engineering for Research, University of Toyama, 3190 Gofuku, Toyama, 930-8555, Japan.
Department of Health Technology, Technical University of Denmark, Building 349, 2800 Kgs., Lyngby, Denmark.
J Med Ultrason (2001). 2020 Oct;47(4):493-500. doi: 10.1007/s10396-020-01038-2. Epub 2020 Aug 4.
In the early stages of atherosclerosis, the luminal surface of the arterial wall becomes rough due to injury and detachment of endothelial cells. This roughening can potentially be estimated with ultrasound since the electrical echo signal from the transducer is sensitive to both the angle of incidence to an extended surface as well as the roughness of the surface. Specifically, as the roughness of an interface increases, specular reflection is substituted by scattering. We propose a method that attempts separation of reflection and backscattering components in the received echo signals.
Assuming the predominant propagation directions of the reflected and scattered waves can be somewhat controlled by the emitted sound field, separation of those components was attempted using synthetic aperture imaging with a transmit beam, focused at a point more distant than the imaging depth. Specifically, two dedicated beamforming processes were used for generation of reflection-emphasized and backscattering-emphasized images.
Experimental verifications on a phantom using an ultrasound system with a limited number of active transmit-receive channels yielded a difference between these two images of 8 dB. The results further showed a similar (slightly improved) lateral spatial resolution size of 0.41 mm for the backscattering-emphasized image compared with conventional B-mode imaging (0.47 mm).
A new technique for separation of the reflection and backscattering components using synthetic aperture beamforming with a transmit beam featuring a large focal distance was proposed. The technique demonstrated a partial separation of the reflection and backscattering components, which potentially may be used to estimate surface roughness.
在动脉粥样硬化的早期阶段，由于内皮细胞的损伤和脱落，动脉壁的管腔表面变得粗糙。由于换能器的电回波信号对扩展表面的入射角以及表面的粗糙度都很敏感，因此超声技术有可能对这种粗糙化进行估计。具体而言，随着界面粗糙度的增加，镜面反射会被散射取代。我们提出了一种尝试分离接收回波信号中反射和背向散射分量的方法。
假设反射和散射波的主要传播方向可以通过发射声场进行一定程度的控制，使用合成孔径成像技术，在发射波束中聚焦于成像深度以外的点，尝试分离这些分量。具体来说，使用两个专门的波束形成过程来生成反射增强和背向散射增强图像。
在具有有限数量主动发射-接收通道的超声系统上对体模进行的实验验证表明，这两种图像之间存在 8dB 的差异。结果还表明，与传统的 B 模式成像（0.47mm）相比，背向散射增强图像的侧向空间分辨率尺寸相似（略有改善），为 0.41mm。
提出了一种使用具有大焦距发射波束的合成孔径波束形成技术来分离反射和背向散射分量的新技术。该技术证明了反射和背向散射分量的部分分离，这可能有助于估计表面粗糙度。
