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Title: Computed tomography , diploic vessels and human evolution: a preliminary comparison in physical and digital specimens
Authors: Rangel de Lázaro, Gizéh
Cuétara, José Manuel de la
Lorenzo Merino, Carlos
Bruner, Emiliano
Issue Date: 2014
Publisher: International Union for Prehistoric and Protohistoric Sciences (IUPPS)
Citation: XVII World UISPP Congress, 2014, p. 933
Abstract: The diploic channels were identified in mammals over 200 years ago, and subsequently described in humans by Gilbert Breschet in 1829. However, diploic veins are scarcely considered in current anatomical studies. This vascular network appears to be more developed in humans than in non-human primates, which suggests this topic may be relevant in evolutionary biology. Diploic vessels grow in the spongy tissue between the cranial tables (internal and external), mostly within frontal and parietal bones, with large veins connected through a complex network of microscopic channels. The vessels are valvesless. Quantitative studies on diploic channels in extinct human species can supply information on vascular evolution and endocraneal thermoregulation, specifically brain cooling. The aim of this study is to determine the application of computed tomography (CT) in digital analysis of diploic vascular system in human anatomy and paleoanthropology. We analyze potentiality and limits of CT to evidence and reconstruct diploic channels in modern and fossil specimens. A first modern sample included 10 physical skulls CT scanned at high resolution (pixel size and slice thickness 0.25 mm). Physical specimens were checked by transillumination and their digital replica by computed imaging. Transillumination equipment was performed with two Cool-White LEDs, of 1500 lumens each. Predominant wavelengths were 450 nm and 600 nm, with a minimum peak at 490 nm and correlated color temperature was in the range of 5000-8300 K. A second modern sample included 10 digital skulls scanned at medium resolution (pixel size and slice thickness between 0.30 and 0.40 mm). We considered CT scans from three Neanderthal skulls: Saccopastore 1, Spy 1, and Spy 2. Digital imaging was computed by using Mimics 10.01 and Image JA 1.45b. One skulls of each sample was analyzed in high, medium and low resolution, to evaluate the effect of different degree of resolution on diploic channels visualization. In the current physical sample (mean vault thickness = 5.2 ± 1.1 mm) transillumination is not able to reveal the presence or patterns of diploic network, giving only minor information on the imprints of middle meningeal vessels. To achieve 3D reconstruction of diploic veins without the diploe noise interference we created a specific protocol to filter the original CT images. Most channels are observed with pixel size and slice thickness at 0.25 mm, at this resolution 3D reconstruction is partially confused because of the noise introduced by spongy tissue. At lower resolution only the largest channels can be recognized. Transillumination is not an informative method to investigate diploic channels in physical samples. The protocol used for treating CT images with digital software was successful for perform anatomical surveys in modern and fossil human remains, providing an important tool to investigate the evolution of cranial vascular networks in extinct human species.
Type: Presentation
Appears in Collections:Congresos, encuentros científicos y estancias de investigación

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