Virtual autopsy using multislice computed tomography in forensic medical diagnosis of drowning

The role of paranasal sinus fluid in determining drowning as the cause of death: A systematic review and meta-analysis

Drowning is a significant global cause of unintentional injury fatalities, and accurate forensic diagnosis of drowning remains a challenge due to the nonspecific nature of post-mortem findings obtained through classical autopsy methods. Our manuscript addresses this issue by focusing on the emerging use of paranasal sinus fluid as a valuable tool in determining the cause of death, specifically in distinguishing drowning from non-drowning cases. The study provided a comprehensive summary of available evidence from observational studies that compared findings in the paranasal sinuses between drowning and non-drowning victims, analyzing parameters such as the presence of fluid, fluid volume, and density. The study encompassed a total of 14 selected studies involving 1044 subjects and utilized rigorous risk of bias assessment and data synthesis techniques. The meta-analysis demonstrated a strong association between the presence of fluid in the paranasal sinuses and drowning (OR = 17.1; 95% CI 7.2 to 40.5; p < 0.001). In addition, drowning victims had a significantly greater volume of fluid (SMD = 0.8; 95% CI 0.5 to 1.2; p < 0.001) and lower fluid density (SMD = -1.4; 95% -2.5 to -0.4; p = 0.008) compared to non-drowning cases. The results support the utility of paranasal sinus fluid analysis as a valuable diagnostic method in cases where drowning is suspected but cannot be definitively confirmed through traditional approaches.

Haematic silicon in drowning

The aim of this paper was to evaluate silicon (Si) concentration in human whole ventricular blood as a further potential chemical marker in the diagnosis of drowning. We employed an acidic digestion for the extraction of soluble Si, and an alkaline digestion for the determination of total Si, including particulate matter, both arising from drowning medium. 29 suspected drowning situations, 24 in fresh water (Fw) and 5 in seawater (Sw), were examined. The difference in Si concentration between the left and right ventricular blood (Si ΔL-R) was measured and alkaline Si ΔL-R seems, indeed, a potentially significant complementary tool in the diagnosis of Fw drowning, because insoluble silicon fraction does not undergo hemo-dilution or hemo-concentration, and the ΔL-R is not affected by exogenous factors. In spite of the limited number of cases investigated, a good correlation was observed between the analytical results and the macro-microscopic autoptic findings.

Freshwater drowning in a child: A case study demonstrating the role of post-mortem computed tomography

In recent years, modern imaging techniques have gained ground in forensics. A crucial question is whether virtual autopsy is capable of replacing traditional autopsy. Forensic diagnosis of freshwater drowning (FWD) is based on the evidence of findings from external inspection (e.g. frothy fluid exuding from the mouth and nostrils), internal examination (e.g. pulmonary congestion, enlargement of heart chambers) and biochemical analysis (haemodilution), findings which are non-specific. The detection of diatoms in organs of the systemic circulation may be of some assistance, but this analysis is rarely performed and is of debatable validity. An 18-month-old child was found dead at home in a swimming pool. Considering the family's wishes to avoid autopsy, the district attorney authorised a whole-body post-mortem computed tomography scan (PMCT). The main imaging findings were frothy fluid in the upper airways, fluid in the trachea and main bronchi, many pulmonary nodular ground glass opacities (GGO) in non-dependent regions and haemodilution. CT imaging did not show any other forensically relevant abnormality.A high concordance was found between the CT findings reported in the literature in cases of FWD and the imaging results. Thus, after the exclusion of other causes of death, advised by the forensic pathologist, the district attorney closed the case and the death was attributed to FWD. This case report demonstrates that PMCT imaging in cases of suspected FWD can provide some important findings for the diagnosis of FWD as the cause of death.

Distinction between saltwater drowning and freshwater drowning by assessment of sinus fluid on post-mortem computed tomography

OBJECTIVE

To evaluate the difference in sinus fluid volume and density between saltwater and freshwater drowning and diagnose saltwater drowning in distinction from freshwater drowning.

METHODS

Ninety-three drowning cases (22 saltwater and 71 freshwater) were retrospectively investigated; all had undergone post-mortem CT and forensic autopsy. Sinus fluid volume and density were calculated using a 3D-DICOM workstation, and differences were evaluated. Diagnostic performance of these indicators for saltwater drowning was evaluated using a cut-off value calculated by receiver operating characteristic (ROC) analysis.

RESULTS

The median sinus fluid volume was 5.68 mL in cases of saltwater drowning (range 0.08 to 37.55) and 5.46 mL in cases of freshwater drowning (0.02 to 27.68), and the average densities were 47.28 (14.26 to 75.98) HU and 32.56 (-14.38 to 77.43) HU, respectively. While sinus volume did not differ significantly (p = 0.6000), sinus density was significantly higher in saltwater than freshwater drowning cases (p = 0.0002). ROC analysis for diagnosis of saltwater drowning determined the cut-off value as 37.77 HU, with a sensitivity of 77 %, specificity of 72 %, PPV of 46 % and NPV of 91 %.

CONCLUSION

The average density of sinus fluid in cases of saltwater drowning was significantly higher than in freshwater drowning cases; there was no significant difference in the sinus fluid volume.

KEY POINTS

• Sinus fluid density of saltwater drowning is significantly higher than freshwater drowning. • Cut-off value was 37.77 HU based on the ROC analysis. • The cut-off value translated to 91 % NPV for diagnosis of saltwater drowning.

Testing photogrammetry-based techniques for three-dimensional surface documentation in forensic pathology

Three-dimensional surface technologies particularly close range photogrammetry and optical surface scanning have recently advanced into affordable, flexible and accurate techniques. Forensic postmortem investigation as performed on a daily basis, however, has not yet fully benefited from their potentials. In the present paper, we tested two approaches to 3D external body documentation - digital camera-based photogrammetry combined with commercial Agisoft PhotoScan(®) software and stereophotogrammetry-based Vectra H1(®), a portable handheld surface scanner. In order to conduct the study three human subjects were selected, a living person, a 25-year-old female, and two forensic cases admitted for postmortem examination at the Department of Forensic Medicine, Hradec Králové, Czech Republic (both 63-year-old males), one dead to traumatic, self-inflicted, injuries (suicide by hanging), the other diagnosed with the heart failure. All three cases were photographed in 360° manner with a Nikon 7000 digital camera and simultaneously documented with the handheld scanner. In addition to having recorded the pre-autopsy phase of the forensic cases, both techniques were employed in various stages of autopsy. The sets of collected digital images (approximately 100 per case) were further processed to generate point clouds and 3D meshes. Final 3D models (a pair per individual) were counted for numbers of points and polygons, then assessed visually and compared quantitatively using ICP alignment algorithm and a cloud point comparison technique based on closest point to point distances. Both techniques were proven to be easy to handle and equally laborious. While collecting the images at autopsy took around 20min, the post-processing was much more time-demanding and required up to 10h of computation time. Moreover, for the full-body scanning the post-processing of the handheld scanner required rather time-consuming manual image alignment. In all instances the applied approaches produced high-resolution photorealistic, real sized or easy to calibrate 3D surface models. Both methods equally failed when the scanned body surface was covered with body hair or reflective moist areas. Still, it can be concluded that single camera close range photogrammetry and optical surface scanning using Vectra H1 scanner represent relatively low-cost solutions which were shown to be beneficial for postmortem body documentation in forensic pathology.

Post-mortem evaluation of drowning with whole body CT

PURPOSE

The aim of this study is to investigate the value of whole body computed tomography (WB-CT) in bodies recovered from water by analysis of the imaging findings after drowning.

METHODS

The bodies of 41 drowning victims and 9 persons who died from mechanical asphyxia by hanging underwent post-mortem whole body computed tomography.

RESULTS AND CONCLUSIONS

Excessive fluid in the paranasal sinuses (98%), nasal pharynx (98%), oropharynx (95%), trachea (83%), ground glass opacities in the lung (89%), pleural fluid (71%), pericardial fluid (59%), esophageal fluid (81%), stomach fluid and distension (71%), duodenal (34%) and jejunal distension (31%) were the most frequent drowning related imaging findings which significantly differed from the group of mechanical asphyxia by hanging. In cases of fresh water drowning hemodilution was present in 79%. New and up to now unpublished findings were lower density in the spleen, indicative for hemodilution and detection of a pronounced amount of pericardial fluid, only seen in drowning victims.

Role of virtopsy in the post-mortem diagnosis of drowning

PURPOSE

Due to admitted limits of autopsy-based studies in the diagnosis of drowning, virtopsy is considered the new imaging horizon in these post-mortem studies. The aim of our study was to evaluate the role of virtopsy performed through computed tomography (CT) in the forensic diagnosis of drowning.

MATERIALS AND METHODS

We retrospectively examined the CT data of four cadavers recovered from sea water and suspected to have died by drowning. Each patient underwent a full-body post-mortem CT scan, and then a traditional autopsy.

RESULTS

All the cadavers showed fluid in the airways and patchy ground-glass opacities in the lung. Only one patient had no fluid in the digestive tract; this patient had a left parietal bone fracture with a large gap and other multiple bone fractures (nose, clavicle, first rib and patella). One of the three patients who had fluid in the digestive tract had no fluid in the paranasal sinuses. This latter patient showed cerebral oedema with subarachnoid and intraventricular haemorrhage, multiple bone fractures (orbital floor, ribs, sacrum and acetabular edge) and air in the heart, in the aorta and in bowel loops.

CONCLUSION

To date, there are no autopsy findings pathognomonic of drowning. This study proves that virtopsy is a useful tool in the diagnosis of drowning in that it allows us to understand if the victim was alive or dead when he entered the water and if the cause of death was drowning.