Development and validation of a postmortem radiological alteration index: the RA-Index

Area of Science:

• Forensic radiology
• Postmortem imaging
• Cadaveric alteration assessment

Background:

• Assessing cadaveric alteration is crucial in forensic science.
• Quantifying gas presence in decomposing bodies is challenging.
• Postmortem multidetector computed tomography (MDCT) offers detailed anatomical visualization.

Purpose of the Study:

• To develop and validate a novel index, the Radiological Alteration (RA)-index, for quantifying cadaveric gas.
• To assess the sensitivity and specificity of the RA-index in postmortem MDCT imaging.
• To establish a reliable and rapid method for evaluating gas distribution in deceased individuals.

Main Methods:

• Derivation of the RA-index from postmortem MDCT data of 118 nontraumatically deceased individuals.
• Validation using 100 additional scanned bodies (50% traumatic deaths) examined by two independent observers.
• Assessment of gas presence at 82 sites, with the RA-index focusing on seven key sites.

Main Results:

• The RA-index showed a strong correlation with overall gas presence (R²=0.98 derivation, R²=0.85 validation).
• The overall RA-index demonstrated high reliability (ICC=0.95).
• Sensitivity for detecting gas in heart cavities was 100%, with 98.8% specificity.

Conclusions:

• The RA-index is a valid, rapid, and reliable tool for measuring gas distribution due to cadaveric alteration.
• It is user-friendly, even for non-experienced personnel.
• MDCT with the RA-index can aid in screening for gas embolism and guide further analysis.