using light later I'm going to show you we can see the color differences of the two forms of blood oxygenated blood and deoxygenated blood red versus blue our veins you know look blue right the arteries will look red so ultrasound will not be able to tell the difference that's just one example this is the first set of functional photoacoustic images it's also the first set of in vivo images acquired using photo acoustic CT this was reported in 2003 by our lab and we can see actually brain activation if he we go one side of the whiskers of