Figure 2: Examples of MIP images of the bird view illustrating depth performance.

The color of PA signal corresponded to the depth scaled by Fig. 1(g). The linear PA signal marked by white filled circles was considered to be the identical blood vessel judging from the continuity of the PA signal. Slightly bigger white filled circle indicated by the orange arrow was the deepest point from the skin surface in these circles. Estimated depths from skin were (a) 24 mm in Case 1 and (b) 27 mm in Case 2. (See Supplemental Multimedia Files).