Pros and cons of post-mortem CT imaging on aspiration diagnosis
Introduction
Aspiration is defined as the inhalation of endogenous or foreign material into the deep respiratory tracts. The detection of signs of aspiration at autopsy is a common task with a high degree of forensic relevance due to the information provided about whether an injury occurred pre-mortem and/or it was the primary, or contributing cause of death.
Traditionally, the diagnosis of aspiration is based on the macroscopic inspection of the airways and lungs during autopsy [1]. However, microscopic findings of deep aspiration in alveoli and bronchioles should always accompany this diagnosis, though the histological appearance of vital aspiration foci varies depending on survival time, the size of the foci, and the nature of the aspirated material [1], [2], [3], [4], [5]. A diagnosis of aspiration as the primary or contributing cause of death can be reached only after considering the extent and quality of the histological findings.
Many authors have attempted to identify clinical CT findings of aspiration [6], [7], [8], [9], [10], [11], [12], [13] for therapy and definition of prognosis. On the contrary, few studies have focused on the appearance of aspiration in post-mortem CT images [14], [15], [16], [17]; most of them concern imaging findings of water aspiration in cases of death by drowning [15], [16]. Although Thali et al. reported post-mortem CT findings of aspiration of more than one material in the pilot paper of the Virtopsy® project [14], a comparison between different pulmonary imaging findings in cases of aspiration of diverse materials has never been conducted.
The aim of this retrospective study was to describe the post-mortem CT images of the lungs and airways in cases of aspiration (such as blood, fresh water, and gastric content) and to evaluate them with autopsy findings to identify the nature of aspirated materials and to distinguish them from changes due to other pathological causes.
Section snippets
Study population
The study was approved by the local Ethics Committee. Between January 2005 and December 2008, a total of 359 human corpses underwent multi-detector CT scanning, at the Institute of Forensic Medicine in Bern, prior to autopsy as part of the Virtopsy® project.
We reviewed the final autopsy reports related to 359 cases with the following selection criteria: documentation of blood, fresh water, and/or gastric content aspiration upon macroscopic and/or microscopic examination of airways and pulmonary
Autopsy
The results of autopsy are reported separately for the three groups.
Discussion
This study showed broad concordance between post-mortem CT and autopsy. However, there were some discrepancies in sensitivity and specificity between them, which require explanation.
Differences were noted between CT and autopsy for the assessment of the localization and amount of aspirated materials in the large airways. Two reasons are considered: (1) some cases had minimal or only a small amount of aspirated materials recognizable only by autopsy, and (2) movement of fluids within the airways
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