Post-mortem CT: Hounsfield unit profiles obtained in the lungs with respect to the cause of death assessment

Lung densitometry in postmortem computed tomography - comparison across different fatal asphyxia groups

Asphyxia as a cause of death poses a diagnostic challenge in forensic medicine due to both the diversity of underlying mechanisms, and lack of specific markers. Acute emphysema or acute alveolar dilation have long been debated as potential findings in these asphyxia cases. To further explore the supplementary findings in our forensic asphyxia cases, this study applied lung densitometry to pulmonary postmortem computed tomography (PMCT) data. Twenty asphyxia cases (including hanging (n = 9), manual strangulation (n = 4), ligature strangulation (n = 1), smothering (n = 3), and choking (n = 3)) and 21 matched control cases were analysed using lung densitometry parameters - specifically quantification of low attenuation areas (LAA) and the 15th percentile point of lung density (Perc15). Our data revealed statistically significantly higher lung % volume falling within LAA at -950HU (p = 0.04) and - 910HU (p = 0.043) in the asphyxia cases compared to matched controls. The Perc15 values observed were trending towards a lower attenuation corresponding to a lower density in the asphyxia group, although this result was not statistically significant (p = 0.13). A subgroup analysis highlighted potential differences within the asphyxia categories, notably, higher Perc15 values were observed in the choking cases. In conclusion the results from the study support the existing evidence of low pulmonary density as a potential finding in asphyxia cases and demonstrate the potential of applying lung densitometry on pulmonary postmortem computed tomography data.

A comparative evaluation of polymeric materials as tissue equivalent phantoms in diagnostic radiology

In this study tissue equivalency of the polymeric materials was investigated by comparing with ICRP 110 Male Adult Computational Phantom tissues. For this purpose, radiological properties of polyamide (PA), high density polyethylene (HDPE), ultra-high molecular weight polyethylene (UHMWPE), polypropylene (PP), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polyoxymethylene (POM) and polyurethane foam (PU FOAM) were evaluated in the diagnostic energy range (15-150 keV). The radiological properties of the materials and ICRP 110 Male and Female Adult Computational Phantom tissues were calculated with Phy-X/PSD software. No major differences were seen except for sex-specific organs, and comparisons were made using an adult male phantom. To confirm the results experimentally, a chest phantom was designed with the polymeric materials. The phantom was scanned by Siemens SOMATOM Edge CT device with tube voltage of 120 kVp and Hounsfield Unit (HU) values were measured. In addition, HU values were calculated using theoretical relationships and significant agreement was obtained between measured and calculated HUs. It was determined that PA, PP, UHMWPE and HDPE were equivalent to muscle and adipose tissue, PVC and PTFE were equivalent to mineral bone, PET and POM were equivalent to spongiosa bone and PU FOAM was equivalent to lung tissue.

Hypothermic death resulting from extreme freezing with characteristic postmortem computed tomography findings: A case report and review of the literature

We report a case of hypothermic death that resulted from extreme freezing, with characteristic postmortem computed tomography (PMCT) findings. A 75-year-old man died in a deeply frozen state. In PMCT, there was a lack of increase in the bilateral lung-field attenuation. Urinary retention, with a hypodense area of frozen urine, was observed in the bladder. Changes that appeared to involve the crystallization of serum in frozen blood were observed in the aorta. Based on the scene and his circumstances, it was speculated that he died of hypothermia. Present case and our review revealed that although PMCT findings from hypothermic death that resulted from deep freezing are very rare, the characteristic PMCT findings may help determine the cause of death.

Effects of blood loss on organ attenuation on postmortem CT and organ weight at autopsy

BACKGROUND

Cases of external hemorrhage are difficult to recognize on postmortem computed tomography (PMCT).

PURPOSE

To investigate the effects of blood loss on CT attenuation of the spleen, liver, kidneys, and lungs on PMCT and to assess the relationship between blood loss and organ weight.

METHODS

A total of 125 cases with blood loss were sex- and age-matched to 125 control cases without blood loss. Individual organ attenuation was measured on transverse CT images. Organ weights of the liver, spleen, kidneys, and lung were extracted from the autopsy protocols.

RESULTS

Organ weight was significantly lower in cases with blood loss (lung 30%, spleen 28%, kidneys 14%, liver 18%) than in controls. CT attenuation of the lungs was significantly lower (30%) in cases with blood loss than in controls. CT attenuation of the spleen and kidneys did not significantly differ between cases and controls. CT attenuation of the liver was significantly higher (25%) in cases with blood loss than in controls.

CONCLUSION

Blood loss decreases organ weight and CT attenuation of the lungs but appears to have no significant effect on CT attenuation of the spleen and kidneys. The increased liver attenuation in cases with blood loss compared to controls was an unexpected finding and remains challenging to explain. One probable interpretation refers to different levels of hepatic glycogen; however, further work is warranted to substantiate this hypothesis.

Layering of stomach contents in drowning cases in post-mortem computed tomography compared to forensic autopsy

BACKGROUND

In forensic autopsy, the analysis of stomach contents is important when investigating drowning cases. Three-layering of stomach contents may be interpreted as a diagnostic hint to drowning due to swallowing of larger amounts of water or other drowning media. The authors experienced frequent discrepancies of numbers of stomach content layering in drowning cases between post-mortem computed tomography (PMCT) and autopsy in forensic casework. Therefore, the goal of this study was to compare layering of stomach contents in drowning cases between PMCT and forensic autopsy.

METHODS

Drowning cases (n = 55; 40 male, 15 female, mean age 45.3 years; mean amount of stomach content 223 ml) that received PMCT prior to forensic autopsy were retrospectively analyzed by a forensic pathologist and a radiologist. Number of layers of stomach content in PMCT were compared to number of layers at forensic autopsy.

RESULTS

In 28 of the 55 evaluated drowning cases, a discrepancy between layering of stomach contents at autopsy compared to PMCT was observed: 1 layer at autopsy (n = 28): 50% discrepancy to PMCT, 2 layers (n = 20): 45% discrepancy, and 3 layers (n = 7): 71.4% discrepancy. Sensitivity of correctly determining layering (as observed at forensic autopsy) in PMCT was 52% (positive predictive value 44.8%). Specificity was 46.6% (negative predictive value 53.8%). In a control group (n = 35) of non-drowning cases, three-layering of stomach contents was not observed.

CONCLUSION

Discrepancies of observed numbers of stomach content layers between PMCT and forensic autopsy are a frequent finding possibly due to stomach content sampling technique at autopsy and movement of the corpse prior to PMCT and autopsy. Three-layering in PMCT, if indeed present, may be interpreted as a hint to drowning.