Photoacoustic endoscopic imaging study of melanoma tumor growth in a rat colorectum<i>in vivo</i>

We performed a photoacoustic endoscopic imaging study of melanoma tumor growth in a nude rat <i>in vivo</i>. After inducing the tumor at the colorectal wall of the animal, we monitored the tumor development <i>in situ</i> by using a photoacoustic endoscopic system. This paper introduces our experimental method for tumor inoculation and presents imaging results showing the morphological changes of the blood vasculature near the tumor region according to the tumor progress. Our study could provide insights for future studies on tumor development in small animals.