Ultrafast optical resolution photoacoustic microscopy in vivo

Photoacoustic Imaging (PAI) is an emerging non-ionizing and non-invasive biomedical imaging method in the past few years. PAI can effectively obtain both structural and functional information of bio-tissues, providing an important method for studying the morphological structure and physiological characteristics of bio-tissues, especially suitable for early-stage cancer diagnosis. As one important subtype of PAI, optical resolution photoacoustic microscopy (ORPAM) has the advantages of high spatial resolution and imaging contrast. ORPAM has been proved to be an effective and powerful method in hemodynamic and micro-circulation studies. However, due to the low scanning speed over a large field of view (FOV), the application of existing ORPAM systems has been greatly limited. In order to overcome these limitations, we report an ultrafast ORPAM (U-ORPAM) system in this research. By combining our novel rotary scanning protocol with a 200 kHz ultrafast pulsed laser, U-ORPAM has the ability to image an 8-mm-diameter FOV in 5 seconds. Both phantom and in vivo experiments were carried out to demonstrate the performance of the image system. These results indicate that U-ORPAM has equivalent imaging qualities with other ORPAM systems with a much higher imaging speed. These advantages make U-ORPAM a promising tool for the investigation of rapid hemodynamic research and clinical biomedical research.