IEEE Trans Ultrason Ferroelectr Freq Control. 2021 Apr;68(4):1213-1223. doi: 10.1109/TUFFC.2020.3035784. Epub 2021 Mar 26.
Focused ultrasound (FUS) therapies induce therapeutic effects in localized tissues using either temperature elevations or mechanical stresses caused by an ultrasound wave. During an FUS therapy, it is crucial to continuously monitor the position of the FUS beam in order to correct for tissue motion and keep the focus within the target region. Toward the goal of achieving real-time monitoring for FUS therapies, we have developed a method for the real-time visualization of an FUS beam using ultrasonic backscatter. The intensity field of an FUS beam was reconstructed using backscatter from an FUS pulse received by an imaging array and then overlaid onto a B-mode image captured using the same imaging array. The FUS beam visualization allows one to monitor the position and extent of the FUS beam in the context of the surrounding medium. Variations in the scattering properties of the medium were corrected in the FUS beam reconstruction by normalizing based on the echogenicity of the coaligned B-mode image. On average, normalizing by echogenicity reduced the mean square error between FUS beam reconstructions in nonhomogeneous regions of a phantom and baseline homogeneous regions by 21.61. FUS beam visualizations were achieved, using a single diagnostic imaging array as both an FUS source and an imaging probe, in a tissue-mimicking phantom and a rat tumor in vivo with a frame rate of 25-30 frames/s.
聚焦超声（FUS）疗法通过利用超声波引起的温度升高或机械应力来在局部组织中产生治疗效果。在 FUS 治疗过程中，连续监测 FUS 光束的位置以校正组织运动并将焦点保持在目标区域内至关重要。为了实现 FUS 治疗的实时监测，我们开发了一种使用超声背散射实时可视化 FUS 光束的方法。使用成像阵列接收的 FUS 脉冲的背散射来重建 FUS 光束的强度场，然后将其叠加在使用相同成像阵列捕获的 B 模式图像上。FUS 光束可视化允许在周围介质的背景下监测 FUS 光束的位置和范围。通过基于煤对齐的 B 模式图像的回声特性进行归一化，在 FUS 光束重建中校正了介质散射特性的变化。平均而言，通过回声特性归一化，将在体模不均匀区域和基线均匀区域中的 FUS 光束重建之间的均方误差降低了 21.61。在组织模拟体模和大鼠肿瘤中，使用单个诊断成像阵列作为 FUS 源和成像探头，以 25-30 帧/秒的帧率实现了 FUS 光束可视化。
