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

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Abstract

This study aimed to derive an index quantifying the state of alteration of cadavers by quantifying the presence of gas in the body using postmortem multidetector computed tomography (MDCT) imaging, and to validate the index by defining its sensitivity and specificity. The RA (radiological alteration)-index was derived from postmortem MDCT data from 118 nontraumatically deceased people. To validate the index, 100 additional scanned bodies (50 % traumatically deceased) were retrospectively examined by two independent observers. Presence of gas at 82 sites was assessed by a radiologist, whereas a forensic pathologist only investigated the seven sites used for the RA-index. The RA-index was highly correlated to the overall presence of gas in all 82 sites (R2 = 0.98 in the derivation set and 0.85 in the validation set). Semiquantitative evaluation of gas presence in each site showed moderate reliability (Cohen's kappa range, 0.41–0.78); nevertheless, the overall RA-index was very reliable (ICC2,1 = 0.95; 95 % CI 0.92–0.96). Examiner using the RA-index detected heart cavities full of gas with a sensitivity of 100 % (95 % CI 51.7–100) and a specificity of 98.8 % (92.6–99.9). We conclude that determining the presence of gas at seven sites is a valid means to measure the distribution of gas due to cadaveric alteration in the entire body. The RA-index is rapid, easy-to-use, and reliable for nonexperienced users, and it is a valid method to suspect the normal presence of gas from cadaveric alteration. MDCT can be used to screen for gas embolism and to give indications for gas composition analysis (gas chromatography).

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Abbreviations

ICC:

Intraclass correlation coefficient

R2 :

Coefficient of determination (equivalent to the squared Pearson's correlation coefficient)

ROC:

Receiver operator curve

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Authors and Affiliations

  1. University Center of Legal Medicine, Lausanne–Geneva, University of Geneva, Rue Michel-Servet 1, 1211, Geneva 4, Switzerland

    C. Egger, P. Vaucher & P. Mangin

  2. Department of Diagnostic and Interventional Radiology, University Hospital Lausanne, Rue du Bugnon 46, 1011, Lausanne, Switzerland

    F. Doenz

  3. University Center of Legal Medicine, Lausanne–Geneva, University of Lausanne, Rue du Bugnon 21, 1011, Lausanne, Switzerland

    C. Palmiere, P. Mangin & S. Grabherr

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  1. C. Egger
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  2. P. Vaucher
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  3. F. Doenz
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  4. C. Palmiere
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  5. P. Mangin
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  6. S. Grabherr
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Correspondence to C. Egger.

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Egger, C., Vaucher, P., Doenz, F. et al. Development and validation of a postmortem radiological alteration index: the RA-Index. Int J Legal Med 126, 559–566 (2012). https://doi.org/10.1007/s00414-012-0686-6

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  • DOI: https://doi.org/10.1007/s00414-012-0686-6

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