In vivo visualization of blood vessels in mouse ear by photoacoustic microscopy with transmissive liquid-crystal adaptive optics

摘要

Photoacoustic microscopy (PAM) is a biological visualization technique that can provide high spatial resolution and highcontrast images of deep structures in living tissues. However, because of the spherical aberration of the objective lens andthe wavefront distortion due to the surface shape and light scattering of the specimen, obtained photoacoustic images indeep tissues are sometimes blurred or distorted. In order to solve this problem, we have developed a PAM using atransmissive liquid-crystal adaptive optics (AO) element. The transmissive and thin structure of the AO element can beeasily installed in the PAM system. Using photoacoustic images of a USAF 1951 resolution test target measured throughthe glass substrate (thickness; 1.5-mm), the lateral resolutions in PAM were estimated with and without the AO element,when a flashlamp-pumped nanosecond pulse laser (pulse width, 5-ns; wavelength, 500-nm) and water-immersion objectivelens (NA = 0.8) were employed. The lateral resolution of PAM at the depth of 1.5-mm was improved from 1.04 ± 0.04 μmto 0.53 ± 0.10 μm by optimizing AO corrections. We have also visualized small blood vessels in mouse ear in vivo byPAM with AO correction. Thus, by optimizing the AO correction according to the imaging depth, our proposed PAMimproves the spatial resolution in biological tissues.