Li Meng-Lin, Zhang Hao E, Maslov Konstantin, Stoica George, Wang Lihong V
Optical Imaging Laboratory, Department of Biomedical Engineering, Texas A&M University, 3120 TAMU, College Station, Texas 77843-3120, USA.
Opt Lett. 2006 Feb 15;31(4):474-6. doi: 10.1364/ol.31.000474.
Recently an in vivo high-resolution backward-mode photoacoustic microscope was developed that shows potential for applications in dermatology and related cancer research. However, the limited depth of focus of the large-numerical-aperture (NA) ultrasonic lens employed in this system causes the image quality to deteriorate significantly in the out-of-focus region. To solve this problem, we devised and explored, for the first time to our knowledge, a virtual-detector-based synthetic-aperture focusing technique, combined with coherence weighting, for photoacoustic microscopy with such a large-NA transducer. Images of phantoms show that the proposed technique improves the -6 dB lateral resolution from 49-379 to 46-53 microm and increases the signal-to-noise ratio by up to 29 dB, depending on the distance from the ultrasonic focal point. In vivo experiments show that the technique also provides a clearer representation of the vascular distribution in the rat's scalp.
最近，一种体内高分辨率反向模式光声显微镜被开发出来，它在皮肤病学和相关癌症研究中显示出应用潜力。然而，该系统中使用的大数值孔径（NA）超声透镜的有限焦深导致离焦区域的图像质量显著下降。为了解决这个问题，据我们所知，我们首次设计并探索了一种基于虚拟探测器的合成孔径聚焦技术，并结合相干加权，用于配备这种大NA换能器的光声显微镜。仿体图像表明，根据与超声焦点的距离，所提出的技术将-6 dB横向分辨率从49 - 379微米提高到46 - 53微米，并将信噪比提高了29 dB。体内实验表明，该技术还能更清晰地呈现大鼠头皮中的血管分布。
