Ophir J, Johnson W, Yazdi Y, Shattuck D, Mehta D
Department of Radiology, University of Texas Medical School, Houston 77030.
Ultrasound Med Biol. 1989;15(4):341-53. doi: 10.1016/0301-5629(89)90046-x.
A recently described method for speed of sound estimation in tissues in pulse-echo mode involves reception of echoes generated by an ultrasonic pulse by means of a linearly tracking transducer. When the peaks of echo amplitudes are used as markers of arrival time, stairstep-like artifacts appear in the echo arrival time vs. transducer position plots. We postulate that these artifacts are a consequence of the speckle phenomenon commonly encountered in ultrasonic imaging. To test this hypothesis, we report computer simulations and water tank experiments which demonstrate similarities between the behavior of the stairsteps and the properties of ultrasonic speckle. Additionally, equations describing the precision of the speed of sound estimation in terms of the second order statistical properties of the stairstep artifact are derived.
一种最近描述的在脉冲回波模式下估计组织中声速的方法，涉及通过线性跟踪换能器接收由超声脉冲产生的回波。当回波幅度的峰值用作到达时间的标记时，在回波到达时间与换能器位置的图中会出现阶梯状伪像。我们推测这些伪像是超声成像中常见的散斑现象的结果。为了验证这一假设，我们报告了计算机模拟和水槽实验，这些实验证明了阶梯的行为与超声散斑的特性之间的相似性。此外，还推导了根据阶梯状伪像的二阶统计特性描述声速估计精度的方程。
