Scanning photon density angiography of superficial vessels
J. Halfmann, R. Schutz, G. Muller
LMTB, Berlin, Germany
Superficial vessels are labelled with the fluorescence marker indocyanine green which is binding to serum allumin. With a intensity modulated laser diode (775 nm, 220 MHz) the fluorescence is excited. The emitted modulated fluorescence intensity originating from the vessel is detected from a small area around the incident laser beam. The intensity and the relative phase shift is obtained. By fast scanning the two dimensional course of the vessels inside the tissue can be determined. With the knowledge of the mean optical parameters of the different tissue layers the depth of the vessels can also be calculated. A simple method will be described how optical parameters can be calculated from backcsattering data from the surface. This method can be used to see the course of vessels and to see the perfusion of certain areas, e.g. after an anastomoses.