IEEE Trans Med Imaging. 2019 Jan;38(1):124-133. doi: 10.1109/TMI.2018.2857481. Epub 2018 Jul 19.
In an increasing number of applications of focused ultrasound (FUS) therapy, such as opening of the blood-brain barrier or collapsing microbubbles in a tumor, elevation of tissue temperature is not involved. In these cases, real-time visualization of the field distribution of the FUS source would allow localization of the FUS beam within the targeted tissue and allow repositioning of the FUS beam during tissue motion. In this paper, in order to visualize the FUS beam in situ, a 6-MHz single-element transducer ( f /2) was used as the FUS source and aligned perpendicular to a linear array which passively received scattered ultrasound from the sample. An image of the reconstructed intensity field pattern of the FUS source using bistatic beamforming was then superimposed on a registered B-mode image of the sample acquired using the same linear array. The superimposed image is used to provide anatomical context of the FUS beam in the sample being treated. The intensity field pattern reconstructed from a homogeneous scattering phantom was compared with the field characteristics of the FUS source characterized by the wire technique. The beamwidth estimates at the FUS focus using the in situ reconstruction technique and the wire technique were 1.5 and 1.2 mm, respectively. The depth-of-field estimates for the in situ reconstruction technique and the wire technique were 11.8 and 16.8 mm, respectively. The FUS beams were also visualized in a two-layer phantom and a chicken breast. The novel reconstruction technique was able to accurately visualize the field of an FUS source in the context of the interrogated medium.
在越来越多的聚焦超声（FUS）治疗应用中，如打开血脑屏障或使肿瘤中的微泡破裂，不涉及组织温度升高。在这些情况下，实时可视化 FUS 源的场分布将允许在靶向组织内定位 FUS 光束，并允许在组织运动期间重新定位 FUS 光束。在本文中，为了原位可视化 FUS 光束，使用了 6MHz 的单元件换能器（f/2）作为 FUS 源，并与线性阵列垂直对准，该线性阵列被动地接收来自样品的散射超声。然后，使用双基地波束形成重建 FUS 源的重建强度场图案的图像被叠加在使用相同线性阵列获得的样品的已注册 B 模式图像上。叠加图像用于提供正在治疗的样品中的 FUS 光束的解剖背景。从均匀散射体中重建的强度场图案与通过线技术表征的 FUS 源的场特性进行了比较。使用原位重建技术和线技术在 FUS 焦点处估计的波束宽度分别为 1.5mm 和 1.2mm。原位重建技术和线技术的景深估计分别为 11.8mm 和 16.8mm。还在两层体模和鸡胸肉中可视化了 FUS 光束。该新的重建技术能够准确地在被询问介质的上下文中可视化 FUS 源的场。
