Towards High-Resolution Ultrasound Neuromodulation With Crossed-Beam Phased Arrays
Towards High-Resolution Ultrasound Neuromodulation With Crossed-Beam Phased Arrays
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DOI：
10.1109/tbcas.2023.3285724
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发表时间：
2023-06
影响因子：
5.1
通讯作者：
S. Ilham;M. Kiani
中科院分区：
文献类型：
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作者：
S. Ilham;M. Kiani
经颅聚焦超声刺激（tFUS）已成为一种潜在的无创治疗技术。由于高超声（US）频率下的颅骨衰减，具有足够穿透深度的成功tFUS需要亚MHz US波，导致相对较差的刺激特异性，特别是在轴向方向（垂直于US换能器）。这个缺点可以通过利用在时间和空间上适当交叉的两个单独的US波束来克服。对于大规模tFUS，还需要相控阵列来动态地将聚焦的US波束转向期望的神经目标。本文介绍了理论基础和优化（通过波传播模拟器）的交叉波束形成使用两个美国相控阵。它还通过实验验证了交叉波束形成与两个定制的32元件相控阵列（工作在555.5 kHz）相对定位在不同的角度。在测量中，亚MHz交叉波束相控阵列在46 mm的焦距处实现了0.8/3.4 mm的横向/轴向分辨率，相比之下，单个相控阵列在50 mm焦距处的横向/轴向分辨率为3.4/26.8 mm（在减小主聚焦区面积方面提高了28.4倍）。在大鼠头骨和组织层的存在下的交叉束形成也在测量中得到验证。
Transcranial focused ultrasound stimulation (tFUS) has emerged as a potential noninvasive therapeutic technology. Due to skull attenuations at high ultrasound (US) frequencies, successful tFUS with sufficient penetration depth requires sub-MHz US waves, leading to relatively poor stimulation specificity particularly in the axial direction (perpendicular to the US transducer). This shortcoming can potentially be overcome by utilizing two individual US beams properly crossed in time and space. For large-scale tFUS, a phased array is also required to dynamically steer focused US beams at desired neural targets. This article presents the theoretical foundation and optimization (through a wave-propagation simulator) of crossed-beam formation using two US phased arrays. It also experimentally validates crossed-beam formation with two custom-made 32-element phased arrays (operating at 555.5 kHz) positioned relatively at different angles. In measurements, the sub-MHz crossed-beam phased arrays achieved 0.8/3.4 mm lateral/axial resolution at a focal distance of ∼ 46 mm, compared to the lateral/axial resolution of 3.4/26.8 mm of the individual phased array at 50 mm focal distance (∼ 28.4-fold improvement in reducing the main focal zone area). The crossed-beam formation in the presence of a rat skull and a tissue layer was also validated in the measurements.