Automated Measurement Technique for the Determination of Regional Skull and Scalp Constituent Thickness

The human skull is a multi-layered composite system critical in protecting the brain during head impact. Head impact studies investigating skull injury thresholds have suggested that the skull and scalp thickness affect the risk of fracture. Therefore, accurately determining the dimensions of skull-scalp constituents is a necessary step in attributing the contribution to response, failure mechanisms and in developing high fidelity human models. However, prior methods to collect these data include physical measurements of biopsies and manual segmentation in X-ray images. These methods are invasive and impractical for clinical applications, or insufficient to characterize the regional variance in the skull-scalp constituents for a full mechanical strength characterization. The newly developed methods in this study describe an automated, regional, and objective-based measurement technique to characterize the average thickness and variance in skull and scalp constituents using quantitative computed tomography (QCT). The developed approach was successfully employed on 7 specimens at 5 anatomically defined locations. Results report the thicknesses for each layer, with the layer of greatest variation being the trabecular bone (diploë) having a standard deviation of 35.6% of its mean thickness. These results will be used to define skull morphology for modeling relative impact injury risk that will be experimentally validated.