Approaching pulmonary fat embolism on postmortem computed tomography



Pulmonary fat embolism (PFE) is a relevant diagnosis playing a role as a sign of vitality or a cause of death. Its severity is assessed according to histological grading systems like that of Falzi. The aim of this study was to determine the utility of unenhanced postmortem computed tomography (PMCT) for PFE diagnosis based on the detection of fat layers.


Consecutive cases with PMCT and autopsy were studied retrospectively. The case group consisted of cases with positive PFE, and the control group included cases with negative PFE. Three observers independently assessed PMCT data for fat layers in the pulmonary trunk and the right and left pulmonary artery. For cases with fat layers, autopsy protocols were assessed for the cause of death, relation to trauma, and undertaken resuscitation measures.


Eight hundred thirty cases were included: 366 PFE positive cases (144 of Falzi grade 1, 63 of 1.5, 99 of 2, 28 of 2.5, and 32 of 3) and 464 PFE negative cases. Interrater reliabilities varied between substantial and almost perfect, and discrepancies were solved according to majority. Eighteen cases showed fat layers on PMCT (2 controls—traumatic instantaneous deaths—, 16 PFE positive cases). PMCT showed low sensitivity but high specificity for PFE diagnosis. The layers were located at the same position in the pulmonary trunk directly adjacent to the pulmonary valve distal to the right ventricle.


Fat layer on PMCT is a rare finding but relates to PFE diagnosis, especially of severe histological grade. It is to be expected in a typical position within the pulmonary trunk.

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The authors express their gratitude to Emma Louise Kessler, MD, for her generous donation to the Zurich Institute of Forensic Medicine, University of Zurich, Switzerland.

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Correspondence to Vasiliki Chatzaraki.

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Ethical approval was obtained by the Cantonal Ethics Committee of Zurich, Switzerland, Nr. 2015-0686. This article does not contain any studies with animals performed by any of the authors.

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1. Fat layers as a sign of PFE are rare finding on PMCT.

2. Detection of fat layers is significantly associated with positive PFE histological diagnosis, especially of high Falzi grades.

3. Traumatic instantaneous deaths can appear with fat layers on PMCT and negative histology.

4. CPR-induced PFE can appear with fat layers on PMCT.

5. Fat layers on PMCT can be interpreted as a reliable vital sign.

6. Fat layers are revealed in the pulmonary trunk adjacent to the pulmonary valve distal to the right ventricle.

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Chatzaraki, V., Heimer, J., Thali, M.J. et al. Approaching pulmonary fat embolism on postmortem computed tomography. Int J Legal Med 133, 1879–1887 (2019).

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  • Virtopsy
  • Pulmonary fat embolism
  • Falzi
  • Postmortem computed tomography
  • Forensic imaging
  • Autopsy