1.5. Micro-CT analysis of gunshot wounds contaminated with bone fragments

Abstract

Objective To develop a method for differentiating Gunshot Residues (GSR) from bone fragments (BF) at micro-CT analysis, when BF contaminate the entrance gunshot wound. Indeed, when the latter involves an anatomical area in proximity to the bone (e.g. head, thorax, etc.) calcium deposits could contaminate the skin and be misinterpreted as GSR at micro-CT analysis. Material and methods Four different types of decalcifying agents (DEC1 and DEC2 based on chelating agents; DEC3 and DEC4 based on hydrochloric acid), and one radiological method (employing different Grayscale thresholding) were compared. BF before/after decalcification, human skin samples covered by BF (SkinBF), GSR (SkinGSR) and/or GSR/BF (SkinGSR/BF) were analyzed through micro-CT. Results The decalcifying trials performed on BF and SkinBF revealed that DEC1 and DEC3 (applied for 4 h and 30 min, respectively) were unable to completely remove the calcium deposits, whereas DEC2 and DEC4 (applied for 4 h and 30 min, respectively) were effective for the above-mentioned purpose. All the decalcifying solutions, however, highly reduced the GSR amount when applied on SkinGSR and SkinGSR/BF samples. The radiological method underestimated both BF and GSR amounts on SkinBF, SkinGSR, SkinGSR/BF specimens. Conclusion Our pilot study showed that the decalcifying solutions routinely used at histology are effective for removing BF fragments contaminating the gunshot wound, but they significantly reduce the amount of metal particles present.