Increasing the local concentration of microbubbles (MBs) within the blood flow plays a crucial role in several medical applications, but there are few imaging modalities available for volumetric tracking of the aggregated MBs in real time. Here we describe a device integrating acoustic vortex tweezers (AVTs) and ultrasound plane-wave imaging (PWI) to achieve the goal of controlling the spatial distribution of MBs in blood vessels and simultaneously monitoring this process using the same probe. Experiments were conducted using a 5-MHz 2-D array ultrasound probe (with three cycles of excitation at an acoustic pressure of 2000 kPa) and 1.2- [Formula: see text]-diameter MBs at a flow rate of 20 mm/s. The AVT waveform was produced by modulating the repetition frequency of the transmitted pulse asymmetrically (4 and 8 kHz at the inflow and outflow ends, respectively). In order to simultaneously capture MBs and carry out imaging with the same probe, the asymmetric AVT pulse signal and the ultrasound-imaging pulse signal were arranged in a staggered series, and the imaging was carried out using plane-wave pulses at nine angles (-7° to 7°) in compounded PWI (volume rate: 200 Hz). Microscopy observations showed that freely suspended MBs could indeed be gathered by the asymmetric AVT in the flow field to form an MBs cluster with a spot size of about [Formula: see text], which could resist the flow to remain at a fixed location for about 22 s. After the asymmetric AVT signal and the ultrasound-imaging pulse signal were turned on for 1 s, the ultrasound 3-D image showed that the signal intensity of the MB clusters increased by 13.1 dB ± 2.9 dB in relation to the background area. These results show that the proposed strategy can be used to accumulate flowing MBs at a desired location and to simultaneously observe this phenomenon. This tool could be used in the future to improve the outcomes of MB-related treatments for various diseases.

中文翻译：

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使用声学涡旋捕获的微气泡的 3-D 超快超声成像。

增加血流中微泡 (MB) 的局部浓度在多种医学应用中起着至关重要的作用，但可用于实时聚合 MB 的体积跟踪的成像方式很少。在这里，我们描述了一种集成声学涡流镊 (AVT) 和超声平面波成像 (PWI) 的设备，以实现控制血管中 MB 的空间分布并使用同一探头同时监测该过程的目标。使用 5-MHz 2-D 阵列超声探头（在 2000 kPa 声压下进行三个激发周期）和 1.2-[公式：见正文]-直径 MB 以 20 mm/s 的流速进行实验。AVT 波形是通过不对称调制发射脉冲的重复频率（流入和流出端为 4 和 8 kHz，分别）。为了同时捕获MBs并用同一探头进行成像，将非对称AVT脉冲信号和超声成像脉冲信号交错排列，使用9个角度的平面波脉冲进行成像（- 7° 至 7°）在复合 PWI（体积率：200 Hz）中。显微镜观察表明，自由悬浮的 MBs 确实可以被流场中的不对称 AVT 聚集，形成一个约22 秒。在非对称 AVT 信号和超声成像脉冲信号打开 1 s 后，超声 3-D 图像显示 MB 簇的信号强度相对于背景区域增加了 13.1 dB ± 2.9 dB。这些结果表明，所提出的策略可用于在所需位置积累流动的 MB 并同时观察这种现象。该工具将来可用于改善与 MB 相关的各种疾病治疗的结果。