Photoacoustic Tomography of Diabetes and Reporter Genes
Date of Award
Doctor of Philosophy (PhD)
Photoacoustic Tomography (PAT) is a hybrid technology which combines light absorption contrast with ultrasonic detection to achieve deep imaging of normally obscured absorbing molecules in tissue. PAT's inherent background free, super-depth imaging capability makes it particularly well suited for functional and molecular studies. When using visible wavelengths, only a small number of naturally occurring absorbers, namely hemoglobin and melanin, give useful contrast in PAT. However, hemoglobin, as a contrast agent, can yield useful information about metabolic abnormalities in tissues, including blood flow speed, hemoglobin oxygen saturation, and vessel diameters. Such information can be useful in determining disease states; in this work we explore changes related to diabetes. Although much information can be garnered from measuring these two absorbers under different conditions, some molecular processes remain invisible to PAT unless an introduced contrast agent is used.
Contrast agents including nanoparticles and organic dyes, have been used with PAT for various purposes, including lymph node detection. Although many contrast agents can be used, genetically encoded ones are particularly powerful since the contrast appears only under conditions that can be precisely controlled, both spatially and temporally. In this work we explore two different kinds of contrast agents: melanin from tyrosinase and fluorescent proteins.
Igor Efimov, Timothy Fleming, Jean Schaffer