Substantiating microCT for diagnosing bioerosion in archaeological bone using a new Virtual Histological Index (VHI)

Abstract

Recent technological advances have broadened the application of palaeoradiology for non-destructive investigation of ancient remains. X-ray microtomography (microCT) in particular is increasingly used as an alternative to histological bone sections for interpreting pathological alterations, trauma, microstructure, and, more recently, bioerosion with direct or ancillary use of histological indices. However, no systematic attempt has been made to confirm the reliability of microCT for histotaphonomic analysis of archaeological bone. The objective of this study is therefore to compare thin sections of human femora rated with the Oxford Histological Index to microCT sections using the newly developed Virtual Histological Index in order to provide an accessible methodology for the evaluation of bioerosion in archaeological bone. We provide detailed descriptions of virtual sections and assess the efficacy of the method on cranial and postcranial elements, cremated long bones, and faunal samples. The traditional histological and virtual methods showed a strong correlation, providing the first systematic data substantiating lab-based microCT as a suitable alternative tool for reconstructing post-mortem history in the archaeological record, and for the reliable, non-destructive screening of samples for further analyses.

3d Visualization of Bioerosion in Archaeological Bone

“…Turner-Walker (2012) and Yoshino et al (1991) also describe the occupation of Haversian canals by bacteria. While it was not possible to visualize bacterial attack on the canalicular network in these microCT images due to restrictions imposed by scan resolution (Mandl et al, 2022), we detected evidence of bacterial attack within the canals. Sample G Ö01 (Fig.…”

“…The dataset is based on twenty-eight cortical bone samples (twenty femora, two ribs, two parietals, one humerus, one mandibular ramus, and two faunal long bones) from five archaeological sites in Lower Austria (for further details see Supplementary Material S1). Seven human samples derive from the Early Neolithic (Linear Pottery) site of Asparn-Schletz, six from the Early Bronze Age site of Gemeinlebarn A, four from Late Bronze Age Inzersdorf ob der Traisen, seven samples (one faunal and four human) from Late Iron Age Göttlesbrunn, and four (one faunal) from Late Iron Age Roseldorf (see Mandl et al, 2022). The individuals from Gemeinlebarn, Inzersdorf ob der Traisen, and Göttlesbrunn were excavated from prehistoric cemeteries (Fritzl, 2017;Karwowski and Czubak, 2019;Szombathy, 1929Szombathy, , 1934.…”

“…Skull (n = 2), rib (n = 2), humerus (n = 1), and mandible (n = 1) fragments were also sampled, as were cremated long bones (n = 5), and faunal mammalian long bones (n = 2) (Supplementary Material S1). The samples were previously assessed with the Oxford Histological Index (OHI) (Hedges et al, 1995;Millard, 2001) and Virtual Histological Index (VHI) by Mandl et al (2022). All figures were formatted using GIMP software (v. 2.99.6), and the ScientiFig plugin (Aigouy and Mirouse, 2013) for Fiji software (Schindelin et al, 2012).…”

“…Six samples were mounted on carbon planchets and examined with an IT 300 LAB6 (JEOL Ltd.) scanning electron microscope at low vacuum at 25.0 kV under high magnification. Images were taken in backscatter electron mode (see Mandl et al, 2022).…”

“…X-ray computed microtomography (microCT or XRM) is increasingly being used as an alternative to conventional histological methods for the diagnosis of pathological alterations (Rühli et al, 2007), trauma (Baier et al, 2019), and diagenesis (Booth et al, 2016;Dal Sasso et al, 2014;Le Garff et al, 2017;Tripp et al, 2010Tripp et al, , 2018 in modern and archaeological bone. Importantly, a strong correlation has been reported between virtual sections and histological micrographs for the evaluation of microbial bioerosion in ancient samples, along with a Virtual Histological Index (VHI) that can be used as an alternative to, or in conjunction with, indices developed for conventional microscopic methods (Mandl et al, 2022). While assessment of 2D virtual microCT sections using the VHI is sufficient for the rating and diagnosis of bioerosion, volume image data obtained from tomographic methods also allow the rendering and analysis of virtual models using commercially available software.…”