Figure 1

Example of a blood vessel image of the palm taken at a wavelength of 795 nm using the third prototype of our photoacoustic imaging system. (a) Complete maximum intensity projection (MIP) image of the hand; (b) image representing the depth as a colour parameter; (c) MIP image after deletion of the vein image near the skin surface; (d) superimposed image of the binarized coloured lines extracted from the common and proper palmar digital arteries over the original PA image. The original PA image as the background is a greyscale  image after deletion of the depth colour information from Fig. 1c. We labelled the three common palmar digital arteries as B1, B2, and B3 in order of arrangement starting from the radial side and labelled the eight proper palmar digital arteries as A1 to A8 in order of arrangement starting from the radial side of the index finger (see Supplementary movie 1).