IEEE Trans Ultrason Ferroelectr Freq Control. 2022 Jun;69(6):1917-1925. doi: 10.1109/TUFFC.2022.3153929. Epub 2022 May 26.
Thromboembolism in vessels often leads to stroke or heart attack and even sudden death unless brought under control. Sonothrombolysis based on ultrasound contrast agents has shown promising outcome in effective treatment of thromboembolism. Intravascular sonothrombolysis transducer was reported recently for unprecedented sonothrombolysis in vitro. However, it is necessary to provide an imaging guide during thrombolysis in clinical applications for optimal treatment efficiency. In this article, a dual mode ultrasound catheter was developed by combining a 16-MHz high-frequency element (imaging transducer) and a 220-kHz low-frequency element (treatment transducer) for sonothrombolysis in vitro. The treatment transducer was designed with a 20-layer PZT-5A stack with the aperture size of 1.2×1.2 mm, and the imaging transducer with the aperture size of 1.2×1.2 mm was attached in front of the treatment transducer. Both transducers were assembled into a customized 2-lm 10-Fr catheter. In vitro experiment was carried out using a bovine blood clot. Imaging tests were conducted, showing that the backscattering signals can be obtained with a high signal-to-noise ratio (SNR) for the 16-MHz imaging transducer. Sonothrombolysis was performed successfully that the volume of clot was reduced significantly after the 30-min treatment. The size changes of clot were observed clearly using the 16-MHz M-mode imaging during the thrombolysis. The findings suggest that the proposed ultrasound-guided intravascular sonothrombolysis can be enhanced since the position of treatment transducer can be adjusted with the target at the clot due to the imaging guide.
血管内的血栓栓塞常导致中风或心脏病发作，甚至猝死，除非加以控制。基于超声对比剂的声溶栓已显示出在有效治疗血栓栓塞方面有良好的效果。最近报道了一种血管内声溶栓换能器，可实现前所未有的体外声溶栓。然而，在临床应用中，为了达到最佳的治疗效果，有必要在溶栓过程中提供成像引导。本文报道了一种新型的双模态超声导管，它将一个 16MHz 的高频元件（成像换能器）和一个 220kHz 的低频元件（治疗换能器）相结合，用于体外声溶栓。治疗换能器采用 20 层 PZT-5A 堆叠，孔径尺寸为 1.2×1.2mm，治疗换能器前面安装有孔径尺寸为 1.2×1.2mm 的成像换能器。两个换能器被组装成一个定制的 2m 10Fr 导管。使用牛血凝块进行了体外实验。进行了成像测试，结果表明，16MHz 成像换能器可以获得具有高信噪比（SNR）的背向散射信号。成功地进行了声溶栓，在 30 分钟的治疗后，血块的体积明显减少。在溶栓过程中，使用 16MHz M 模式成像可以清楚地观察到血块的大小变化。研究结果表明，由于治疗换能器的位置可以根据目标在血块上进行调整，因此提出的超声引导血管内声溶栓可以得到增强。
