Identification of gunshot entry wounds using hyperdense rim sign on post-mortem computed tomography

Area of Science:

• Forensic Medicine
• Radiology
• Pathology

Background:

• Post-mortem computed tomography (PMCT) is valuable for evaluating head gunshot injuries.
• Distinguishing entry from exit wounds on PMCT can be challenging, especially without the vault bevelling sign.
• A cutaneous hyperdense ring, observed in animal studies, may indicate contact shots and potentially entry wounds in humans.

Purpose of the Study:

• To evaluate the reliability of the cutaneous hyperdense rim sign for identifying entry gunshot wounds in human post-mortem computed tomography (PMCT).
• To assess the specificity and sensitivity of the hyperdense rim sign in differentiating entry from exit wounds.

Main Methods:

• Retrospective analysis of 64 gunshot wounds (30 entry, 34 exit) in 34 head PMCT cases (2018-2022).
• Exclusion of complex and mucosal wounds.
• Definition of the hyperdense rim sign: at least two-thirds of a continuous cutaneous hyperdense circle on multiplanar reconstruction.

Main Results:

• The hyperdense rim sign demonstrated high specificity (97%) and moderate sensitivity (63%) for identifying entry gunshot wounds.
• A positive association was found between the hyperdense rim sign and the presence of powder residues or bullet wipe at the entry wound (p=0.018).
• The gold standard for wound type determination was the autopsy report.

Conclusions:

• The cutaneous hyperdense rim sign is a specific indicator for entry gunshot wounds in PMCT.
• This sign can be a valuable adjunct tool for forensic analysis, particularly when combined with other CT and autopsy findings.
• Further research may explore its utility in various wound scenarios.