Department of Electronic Engineering, Fudan University, Shanghai, China.
Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
Biomed Eng Online. 2019 Jan 23;18(1):7. doi: 10.1186/s12938-019-0629-2.
Ultrasound computed tomography (USCT) is usually realized with a ring array. It can provide better imaging performance and more tissue information by emitting and receiving the ultrasound signal in different directions simultaneously. However, USCT imaging is usually applied with the synthetic aperture (SA) emission method, which leads to a long scanning time with a large number of elements on the ring array. The echo image can provide the structural information, and has a higher resolution than maps of other parameters in USCT. Hence, we proposed plane wave (PW) imaging for ring array to acquire the echo wave and reduce the scanning time considerably.
In this paper, an emitting and receiving process was proposed to realize plane wave imaging with a ring array. With the proposed scanning method, the number of emission events can be reduced greatly. A beamforming method based on the eigenspace-based minimum variance (ESBMV) was also combined with the scanning method. With ESBMV beamformer, the resolution and contrast ratio of reconstruction result can be maintained or even improved under a fewer-emissions condition. We validated the method using both computer simulations with Field II and phantom experiments with a ring array of 512 elements. The Verasonics system was used to transmit and receive the ultrasound signal in the phantom experiments.
According to the results of the experiments, the imaging results will have a better contrast ratio with a higher emitting energy. Additionally, the scanning time with the proposed method can be only one-tenth of that with the SA emission method, while the echo imaging performance still remains at a similar level or even better.
超声计算机断层扫描（USCT）通常采用环形阵列实现。通过同时从不同方向发射和接收超声信号，可以提供更好的成像性能和更多的组织信息。然而，USCT 成像通常采用合成孔径（SA）发射方法，这导致环形阵列上的大量元素的扫描时间很长。回波图像可以提供结构信息，并且在 USCT 中比其他参数的图谱具有更高的分辨率。因此，我们提出了平面波（PW）成像方法，用于环形阵列来获取回波，并大大减少扫描时间。
本文提出了一种利用环形阵列实现平面波成像的发射和接收过程。采用所提出的扫描方法，可以大大减少发射事件的数量。还结合了基于特征空间的最小方差（ESBMV）的波束形成方法和扫描方法。采用 ESBMV 波束形成器，在更少发射条件下，重建结果的分辨率和对比度比仍可以保持甚至提高。我们使用 Field II 的计算机模拟和带有 512 个元素的环形阵列的体模实验验证了该方法。Verasonics 系统用于在体模实验中传输和接收超声信号。
根据实验结果，具有更高发射能量的成像结果将具有更好的对比度。此外，与 SA 发射方法相比，所提出的方法的扫描时间可以仅为其十分之一，而回波成像性能仍保持在相似水平或甚至更好。
