Prospective respiration-gated optical-resolution photoacoustic microscopy to eliminate motion artifacts caused by respiratory of mouse

Photoacoustic microscopy (PAM) is a promising biomedical imaging technique that relies on sequential excitation to generate three-dimensional images. It combines the high contrast of optical imaging with high penetration depth of ultrasound imaging. The normal respiration rate of mice is greater than 3 Hz, which leads to motion artifacts in most reported PAM for in-vivo imaging. Here, we introduce a prospective respiratory gating (PRG) method for photoacoustic microscopy to address this problem. We captured the mouse's respiratory signal with a laser displacement sensor, when the detector detects a respiratory trough, the stage moves a certain number of positions and sends a corresponding number of pulses to trigger the laser light and the data acquisition. The stage will only move during the nadir of respiration, and the movement also must stop before the next respiration peak. We combined this method with our PAM to demonstrate its feasibility. A series of experiments were performed to verify the feasibility of this technology. The carbon fiber attached to the abdomen of mouse was visualized to quantify the performance of the PRG. The subcutaneous vascular imaging results of the mouse abdominal region with PRG are much better than those without any gating. Our experiments show that the proposed method can help to remove motion artifacts well.