Finite amplitude distortion-based inhomogeneous pulse echo ultrasonic imaging
Finite amplitude distortion-based inhomogeneous pulse echo ultrasonic imaging
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DOI：
10.1109/58.585208
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发表时间：
1997-01-01
影响因子：
3.6
通讯作者：
Christopher, T
中科院分区：
文献类型：
--
作者：
Christopher, T
由于非均匀介质的离焦效应，非均匀介质中的超声脉冲回波成像具有显著的横向分辨率和对比度分辨率损失。横向分辨率和对比度分辨率的损失分别与主束宽度的增加和副瓣电平的增加有关。这两种形式的分辨率损失是提高生物医学超声成像临床应用的重大障碍。目前正在进行一些研究工作，以调查组织的散焦效应并考虑纠正措施。所有这些努力都假设线性传播，并将成像过程建立在所传输脉冲的接收之上。这里考虑了一种新的脉冲回波成像方案，其中使用接收脉冲的有限幅度失真分量来形成图像。或者，这可以被描述为使用非线性产生的高次谐波来成像。在均匀光束传输中，非线性高次谐波的旁瓣比线性高次谐波的旁瓣要低得多。这里考虑的计算表明，这种关系也适用于通过腹壁和乳房壁组织传播的情况。这些计算还表明，对于非线性产生的二次谐波，腹壁和乳房壁组织施加的横向分辨率限制比它们的线性对应组织略小。研究了这些高次谐波对提高图像分辨率的潜在作用。
Ultrasonic pulse echo imaging in inhomogeneous media suffers from significant lateral and contrast resolution losses due to the defocusing effects of the inhomogeneities. The losses in lateral and contrast resolution are associated with increases in the width of the main-beam and increases in sidelobe levels, respectively. These two forms of resolution loss represent significant hurdles to improving the clinical utility of biomedical ultrasonic imaging. A number of research efforts are currently under way to investigate the defocusing effects of tissue and to consider corrective measures. All of these efforts assume linear propagation, and base the image-formation process on the reception of the transmitted pulse. A novel pulse echo imaging scheme in which the image is formed using the finite amplitude distortion components of the received pulse is considered here. Alternatively, this could be described as image formation using the nonlinearly-generated higher harmonics. In homogeneous beam propagations, it has been established that the sidelobes of nonlinearly-generated higher harmonics are much lower than their linear counterparts. Computations considered here suggest that this relationship also holds for the case of propagations through abdominal wall and breast wall tissue. These computations also suggest that the lateral resolution limits imposed by abdominal wall and breast wall tissue are slightly smaller for nonlinearly-generated second harmonics than for their linear counterparts. The resulting potential of these higher harmonics to improve image resolution is investigated.