Diploic vessels and computed tomography: segmentation and comparison in modern humans and fossil hominids

Abstract

The diploic channels mostly grow within the frontal and parietal bones. They appear to be more developed in humans than in non-human primates, suggesting a role in evolutionary biology. We provide a segmentation protocol for diploic channels in dry skulls after computed tomography, with a quantitative description of their variation in modern humans and three Neanderthals. Computed tomographic scans were used for 2D and 3D visualization of diploic channels, digital reconstruction and morphometrics. The effect of different resolution factors was evaluated. A specific protocol was designed to segment the vascular network and localize the main branches, reducing the noise of the cancellous bone. We supply a quantitative description of the frontal, parietal, and occipital diploic system in modern human skulls and in three Neanderthals. There is a correlation in the degree of vascularization of the frontal, parietal, and occipital bones, with no patent asymmetry. The diploic network communicates with the meningeal artery at the temporal fossa, with the emissary veins at the occipital bone, and with the venous sinuses at the parieto-occipital areas. The parietal bone is most vascularized than the other districts. In comparison with modern human, Neanderthals show a lower vascular complexity.