Two-Dimensional Photoacoustic Imaging of Blood Vessel Networks within Biological Tissues

Photoacoustic tomography (PAT) is a powerful imaging technique for medical diagnosis because it combines the merits and most compelling features of light and sound. We describe a PAT experimental system constructed in our laboratory which consists of a Q-switched Nd:YAG pulse laser operating at 532nm with a 8-ns pulse width to generate the photoacoustic signals from a biological sample. Two-dimensional photoacoustic imaging of blood vessel networks 1cm below the tissue surface is achieved. We also successfully demonstrate that the system is capable of imaging the blood vessels over the ex vivo rat brain with skull and skin intact.