Kim Hyojin, Kim Jin Young, Cho Seonghee, Ahn Joongho, Kim Yeonggeun, Kim Hyungham, Kim Chulhong
Departments of Electrical Engineering, Convergence IT Engineering, Mechanical Engineering, and Interdisciplinary Bioscience and Bioengineering, Medical Device Innovation Center, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673 Republic of Korea.
Biomed Eng Lett. 2022 Mar 2;12(2):147-153. doi: 10.1007/s13534-022-00218-y. eCollection 2022 May.
Photoacoustic microscopy (PAM) embedded with a 532 nm pulse laser is widely used to visualize the microvascular structures in both small animals and humans in vivo. An opto-ultrasound combiner (OUC) is often utilized in high-speed PAM to confocally align the optical and acoustic beams to improve the system's sensitivity. However, acoustic impedance mismatch in the OUC results in little improvement in the sensitivity. Alternatively, a ring-shaped ultrasound transducer (RUT) can also accomplish the confocal configuration. Here, we compare the performance of OUC and RUT modules through ultrasound pulse-echo tests and PA imaging experiments. The signal-to-noise ratios (SNRs) of the RUT-based system were 15 dB, 12 dB, and 7 dB higher when compared to the OUC-based system for ultrasound pulse-echo test, PA phantom imaging test, and PA in-vivo imaging test, respectively. In addition, the RUT-based system could image the microvascular structures of small parts of a mouse body in a few seconds with minimal loss in SNR. Thus, with increased sensitivity, improved image details, and fast image acquisition, we believe the RUT-based systems could play a significant role in the design of future fast-PAM systems.
嵌入532纳米脉冲激光的光声显微镜（PAM）被广泛用于在体内可视化小动物和人体中的微血管结构。在高速光声显微镜中，通常使用光超声组合器（OUC）来共焦对准光束和声束，以提高系统的灵敏度。然而，光超声组合器中的声阻抗失配导致灵敏度提升不大。另外，环形超声换能器（RUT）也可以实现共焦配置。在此，我们通过超声脉冲回波测试和光声成像实验比较了光超声组合器和环形超声换能器模块的性能。在超声脉冲回波测试、光声体模成像测试和光声体内成像测试中，基于环形超声换能器的系统的信噪比分别比基于光超声组合器的系统高15分贝、12分贝和7分贝。此外，基于环形超声换能器的系统能够在几秒钟内对小鼠身体小部分的微血管结构进行成像，且信噪比损失最小。因此，随着灵敏度的提高、图像细节的改善以及快速图像采集，我们相信基于环形超声换能器的系统在未来快速光声显微镜系统的设计中可以发挥重要作用。
