(a) Phase-gredient images calculated from the raw images of Fig. 5. The structures of trabeculae clearly emerge in the phase contrast, while they are invisible in Fig. 5. (b) Intensity profiles along the black lines in Figs. 5(a), 5(b), and 6(a). The curve at the bottom is a detailed part of the profile. Figures 5(a), 5(b), and 6(a) have the same scale bar.