Identification score for robust and secure identification using ante- and post-mortem skull CT scans

Due to their unique anatomy, paranasal sinuses have been used for comparative identification between post-mortem CT (PMCT) and ante-mortem CT (AMCT). However, data security issues arise when transferring raw AMCT images of a suspected identity. The aim of this study was to derive and validate an identification score based on CT slices extracted from successive CTs for the identification of subjects. For derivation procedure, we included patients who underwent two successive AMCTs at ≥ 1-year interval (n = 98), and 4 radiologists individually assessed similarity of prespecified CT slices (centered on ethmoid, frontal sinus and Left Semi-Circular Canal). Predictive values were calculated for all combinations of number of readers and slices, and the optimal compromise, termed IDScore, was selected. For validation, we included PMCTs performed between 2018 and 2022 with available comparative head AMCTs (n = 27). For each PMCT, 5 comparison procedures were performed: 1 concordant (with corresponding AMCT) and 4 discordant (with randomly selected AMCTs). Two radiologists evaluated similarity of ethmoid and frontal CT slices with a score ranging from -2 to + 2. IDScore was defined as the sum of these slice scores, averaged between the two readers. In the 135 comparison procedures, IDScore using predetermined thresholds (positive identification for IDScore > + 2, negative identification for IDScore