Concentration dependence of optical clearing on the enhancement of laser-scanning optical-resolution photoacoustic microscopy imaging.

Quantitative analysis of optical clearing effects (OCE) induced by hyperosmotic agents is very important to optical tissue clearing applications in biomedical diagnostic imaging and therapeutics. This study aims at investigating the effect of glycerol concentration on the laser-scanning optical-resolution photoacoustic microscopy (LSOR-PAM) imaging contrast and light penetration depth. The photoacoustic (PA) signal amplitude changes are evaluated as a function of the concentration of glycerol. The results reveal that the PA signal amplitudes are enhanced with the glycerol concentration increasing, and also show that higher concentration of glycerol produces better light penetration and OCE on a phantom. The PA signal amplitude increases only 8.1% for 20% glycerol, but for higher concentrations, the increases are 76% and 165% for 40% and 60% glycerol, respectively. This preliminary study demonstrates that application of glycerol as an optical contrast agent reduces the tissue scattering and is beneficial to PAM imaging and optical diagnosis in clinical dermatology.