IEEE Trans Ultrason Ferroelectr Freq Control. 2022 Apr;69(4):1428-1441. doi: 10.1109/TUFFC.2022.3150746. Epub 2022 Mar 30.
Peripheral artery disease (PAD) affects more than 200 million people globally. Minimally invasive endovascular procedures can provide relief and salvage limbs while reducing injury rates and recovery times. Unfortunately, when a calcified chronic total occlusion is encountered, ~25% of endovascular procedures fail due to the inability to advance a guidewire using the view provided by fluoroscopy. To enable a sub-millimeter, robotically steerable guidewire to cross these occlusions, a novel single-element, dual-band transducer is developed that provides simultaneous multifrequency, forward-viewing imaging with high penetration depth and high spatial resolution while requiring only a single electrical connection. The design, fabrication, and acoustic characterization of this device are described, and proof-of-concept imaging is demonstrated in an ex vivo porcine artery after integration with a robotically steered guidewire. Measured center frequencies of the developed transducer were 16 and 32 MHz, with -6 dB fractional bandwidths of 73% and 23%, respectively. When imaging a 0.2-mm wire target at a depth of 5 mm, measured -6 dB target widths were 0.498 ± 0.02 and 0.268 ± 0.01 mm for images formed at 16 and 32 MHz, respectively. Measured SNR values were 33.3 and 21.3 dB, respectively. The 3-D images of the ex vivo artery demonstrate high penetration for visualizing vessel morphology at 16 MHz and ability to resolve small features close to the transducer at 32 MHz. Using images acquired simultaneously at both frequencies as part of an integrated forward-viewing, guidewire-based imaging system, an interventionalist could visualize the best path for advancing the guidewire to improve outcomes for patients with PAD.
外周动脉疾病（PAD）影响着全球超过 2 亿人。微创血管内手术可以提供缓解和挽救肢体的方法，同时降低损伤率和恢复时间。不幸的是，当遇到钙化的慢性完全闭塞时，由于无法使用透视提供的视野推进导丝，约 25%的血管内手术失败。为了使亚毫米级、机器人可转向的导丝能够穿过这些闭塞，开发了一种新型的单元件、双频换能器，它提供了同时的多频率、前视成像，具有高穿透深度和高空间分辨率，同时只需要单个电连接。描述了该设备的设计、制造和声学特性，并在与机器人可转向导丝集成后的离体猪动脉中进行了概念验证成像。所开发的换能器的测量中心频率为 16 和 32 MHz，-6 dB 带宽分别为 73%和 23%。当在 5 毫米深度处对 0.2 毫米的线目标成像时，在 16 和 32 MHz 下分别测量到的-6 dB 目标宽度为 0.498 ± 0.02 和 0.268 ± 0.01 毫米。测量的 SNR 值分别为 33.3 和 21.3 dB。离体动脉的 3-D 图像显示了在 16 MHz 下用于可视化血管形态的高穿透性，以及在 32 MHz 下用于解析靠近换能器的小特征的能力。使用在两个频率下同时获取的图像作为集成前视、基于导丝的成像系统的一部分，介入医生可以可视化推进导丝的最佳路径，以改善 PAD 患者的治疗效果。
