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Objectives The aim of the study was to compare, by means of micro-computed tomography (micro-CT), intermediate gunshot wounds produced on human skin, in order to perform a differential diagnosis between entry (EntW) and exit (ExtW) wounds. Materials and methods Thirty firing trials were carried out at a distance of 15 cm. Six shooting experiments were performed on human calves covered with a single layer of textile; the other 24 firing trials were carried out on bare skin sections. The bare skin specimens ( n =6) and those covered by textile specimens ( n =6) were immediately formalin-fixed. The remaining gunshot wounds were submerged in water for 1 day ( n =6), or enclosed in a cowshed for 15 days ( n =6) or placed inside a wood-burning stove for 4 min ( n =6). The entrance and exit wounds were analyzed macroscopically and microscopically, as well as radiologically using a micro-CT, and the results were compared by blinded investigators. Results At visual inspection, the differential diagnosis between entrance and exit holes was possible only in fresh and submerged gunshot wounds, while the skin of the other types of lesions did not show any of the classical morphological features of entrance wounds. Micro-CT analysis detected radiopaque particles in each experimental sample only on the EntW, while on the ExtW no gunshot residue (GSR) deposits were evident. Conclusion Micro-CT analysis detected GSR in EntW, allowing the performance of a differential diagnosis from the ExtW. This objective and rapid tool may furnish precious information for reconstructing the shooting incident in firearm fatalities.

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.

Objective This study aims at testing MRI for estimating the depth of stab wounds. Material and methods Six stabbing trials were performed on surgically amputated human calves using a knife. After the extraction of the knife the wound cavity was instilled with fresh human blood and subsequently with contrast medium. MRI scans were performed before and after blood instillation (MRI-b) and contrast medium instillation (MRI-cm). Radiological measurements of the length of the cavity (MRI-esteem, MRI-b-esteem and MRI-cm-esteem) were compared to the length of the penetrated blade measured directly on the knife (pBL). Results The mean pBL ranged between 4.8 and 5 cm (mean: 4.9 cm). The mean MRI-esteem, MRI-b-esteem and MRI-cm-esteem were 3.8 cm, 4.1 cm, and 4.5 cm, respectively. Discussion MRI-cm measurements were the most accurate esteem of pBL, confirming the results obtained in a previous study performed on a larger population. MRI-b measurements, although less accurate than MRI-cm-esteem, gave a better prediction of the pBL than the MRI-esteem. The key strength of MRI-b-esteem is that the blood filling the cavity mimics vital bleeding, simulating realistic conditions occurring in living subjects. Moreover, MRI-b does not need any contrast medium instillation, being less invasive and more suitable for a potential forensic application in the living. Conclusion A systematic underestimation of pBL occurs at MRI-b. In order to confirm its potential accuracy and suitability for pBL estimation in living subjects, further experiments are necessary.