School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology, Hefei 230009, China.
School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology, Hefei 230009, China.
Ultrasonics. 2021 Jul;114:106423. doi: 10.1016/j.ultras.2021.106423. Epub 2021 Mar 21.
Compared with B-mode imaging, three-dimensional (3D) ultrasound imaging is more helpful in research and clinical application. At present, the 3D ultrasound images can be acquired directly with two-dimensional (2D) array transducer or reconstructed from a series of B-mode images obtained with one-dimensional (1D) array transducer. Imaging with 2D array transducer can achieve a high frame rate, but suffering from the complexity of the imaging system, such as the large amount of channels, and high computational complexity. Reconstructing 3D images from a series of B-mode images can be implemented by recording the position and orientation of the slice images. This is a low-cost and flexible imaging method, but usually suffering from the low imaging quality and low frame rate. In our previous work, a novel 3D ultrasound imaging method in frequency domain with a moved 1D array transducer is presented. This method can reduce the computational complexity with FFT, and get improved imaging quality and frame rate to some extent. Besides, this method can be adopted to construct images with a row-column-addressed 2D array, which can reduce the amount of channels effectively. In this paper, a two-steps implementation of this imaging method is proposed, in which the combined implementation of the 3D imaging is decomposed to two steps of 2D imaging processes in Frequency domain. In the first step, the received echoes of the 1D array transducer at each position are processed with a 2D imaging processes in the lateral- axial planes. In the second step, a 2D imaging processes is preformed in the planes of orthogonal to the transducer. Simulation results show that the two-steps implementation can achieve almost the same imaging quality to the previous work. Compared with the implementation of 3D imaging in our previous work, the proposed two-steps implementation can be carried out with parallel process to improve the computational efficiency, or carried out with loop to reduce the hardware cost. Besides, the first step can be performed with a conventional DAS imaging method when a cylindrical wave is adopted for imaging. The influence of the spread angle of the field is also discussed.
与 B 模式成像相比，三维（3D）超声成像是在研究和临床应用中更有帮助。目前，可以直接使用二维（2D）阵列换能器获取 3D 超声图像，也可以从一维（1D）阵列换能器获得的一系列 B 模式图像中重建 3D 图像。使用 2D 阵列换能器进行成像可以实现高帧率，但由于成像系统的复杂性，例如大量通道和高计算复杂度，会受到影响。通过记录切片图像的位置和方向，可以从一系列 B 模式图像中重建 3D 图像。这是一种低成本且灵活的成像方法，但通常会受到成像质量和帧率低的影响。在我们之前的工作中，提出了一种使用移动 1D 阵列换能器的频域 3D 超声成像新方法。该方法可以通过 FFT 降低计算复杂度，并在一定程度上提高成像质量和帧率。此外，该方法可用于构建行-列寻址 2D 阵列的图像，可有效减少通道数量。在本文中，提出了这种成像方法的两步实现，其中 3D 成像的组合实现被分解为频域中两个 2D 成像过程的步骤。在第一步中，在横向-轴向平面上对每个位置的 1D 阵列换能器的接收回波进行 2D 成像处理。在第二步中，在与换能器正交的平面上执行 2D 成像处理。仿真结果表明，两步实现可以达到与之前工作几乎相同的成像质量。与我们之前工作中的 3D 成像实现相比，所提出的两步实现可以通过并行处理来提高计算效率，或者通过循环处理来降低硬件成本。此外，当采用圆柱波进行成像时，可以使用常规的 DAS 成像方法来执行第一步。还讨论了场的展宽角的影响。
