Opt Lett. 2013 Oct 15;38(20):4236-9. doi: 10.1364/OL.38.004236.
Acoustic resolution photoacoustic microscopy (AR-PAM) takes advantage of weak acoustic scattering to image fine structures, such as the subcutaneous microvasculature, providing a spatial resolution on the order of tens of micrometers. However, the amplitude of AR-PAM deteriorates sharply with depth, as a result of light scattering and acoustic attenuation caused by structures such as the skin. Optical clearing techniques can enhance optical transmittance by decreasing the scattering of light through tissues. However, it is unknown whether optical clearing agents (OCAs) can be used to improve AR-PAM. We applied different types of OCAs to rat dorsal skin in an ex vivo study to determine the effects of OCAs on photoacoustic detection. We identified three OCAs that improved the photoacoustic amplitude for further in vivo testing. With the use of an appropriate penetration enhancer, PEG-400 significantly improved the photoacoustic amplitude for detection of deep-sealed blood vessels, while glycerol alone improved the image quality of shallow vessels. In contrast, DMSO application resulted in decreased photoacoustic amplitude in the in vivo trials.
声学分辩光声显微镜（AR-PAM）利用弱声散射来成像精细结构，如皮下微血管，提供了几十微米量级的空间分辨率。然而，由于皮肤等结构引起的光散射和声波衰减，AR-PAM 的幅度随深度急剧下降。光学透明技术可以通过减少光在组织中的散射来提高光透过率。然而，尚不清楚是否可以使用光学透明剂（OCAs）来改善 AR-PAM。我们在离体研究中向大鼠背部皮肤应用不同类型的 OCAs，以确定 OCAs 对光声检测的影响。我们确定了三种可以提高光声幅度的 OCA，以便进一步进行体内测试。使用适当的渗透增强剂，PEG-400 显著提高了深层密封血管的光声幅度，而单独使用甘油则提高了浅层血管的图像质量。相比之下，DMSO 的应用导致体内试验中的光声幅度降低。
