Postmortem chest computed tomography for the diagnosis of drowning: a feasibility study

Evaluation of the effect of orthodontic treatment on the reliability of facial recognition by using three-dimensional model superimposition technique

3D-3D registration of facial models, has great advantages in personal individual identification in forensic medicine. However, orthodontic treatment has brought changes in facial soft and hard tissues, which has a potential effect in personal identification. The aim of the study was to explore whether orthodontic treatment affects 3D-3D facial recognition. A total of 68 patients aged between 18 and 38 were selected (30 subjects with tooth extraction, 38 subjects with non-tooth extraction) and a control group consisting of 30 volunteers without orthodontic treatment was selected from a database of 3dMD facial models. 3dMD facial model acquisition was performed twice for each subject. For both extraction and non-extraction groups, T0 was acquired before treatment, and T1 was acquired at the end of treatment. The time span of 2 times 3dMD facial model acquisition in the control group was about 2 years. 3dMD facial models were then registered onto other 3dMD models belonging to the same and different individuals according to the minimum point-to-point distance, getting a cohort of matches and mismatches. Root mean square (RMS) value of the minimum point-to-point distance between two models was then calculated. The intra- and inter-observer repeatability coefficients were 0.986 (P<0.001) and 0.982 (P<0.001). The absolute technical error of measurement (TEM) value was 0.05 mm and 0.04 mm, and relative technical error of measurement (rTEM) value was 4.91 % and 3.60 %, respectively. Possible significant differences between groups were assessed through independent samples t-test or Mann-Whitney U test (p<0.001). The average RMS value was 1.03±0.33 mm in matches of orthodontic group, 0.67±0.22 mm in matches of control group, and 2.66±0.51 mm in mismatches. An RMS value range of 1.70-1.77 mm could distinguish matches from mismatches in 100 % of cases in the present study. This study showed that orthodontic treatment would not affect 3D-3D facial recognition in adults for the purpose of individual identification in forensic medicine.

Diagnosing fatal drownings: A review of the postmortem findings

The lack of drowning-specific pathological findings postmortem complicates medico-legal investigations when bodies are recovered in water. This review provides an in-depth analysis of macroscopic and microscopic findings, as well as biochemical and molecular approaches typically used to diagnose drownings. To ensure that only studies fulfilling established scientific criteria were selected to form conclusions in this review, existing literature was systematically assessed using SPICOT for evaluation of scientific evidence and risk of bias. Analysis of selected studies indicates that several pathophysiological findings following suspected drowning lack scientific evidence, while others are supported by the literature. However, the shortage of suitable controls in drowning research, specifically addressing non-drowned immersed bodies significantly limits investigations on postmortem drowning pathology, and further research is warranted.

Optimization of Postprocessing parameters for abdominal Forensic CT scans

Aim

Postmortem Computed Tomography (PMCT) is gradually introduced at forensic institutes. Image reconstruction software can increase diagnostic potential in CT by increasing distinction between structures and reduction of artifacts. The aim of this study was to develop and evaluate novel image reconstruction parameters for postmortem conditions, to increase image quality and diagnostic potential of CT scans.

Method

Twenty PMCT scans of deceased hereof two in severe decay were subjected to four reconstruction techniques: a standard reconstruction algorithm, the detail reconstruction algorithm and two novel algorithms based on the standard algorithm, but with different Hounsfield settings. Image quality was evaluated by visual grading analysis (VGA) by four forensic radiologist observers.

Results

The VGA did not prove that any of the reconstruction techniques were superior to the others. For standard and detail, the two pre-defined reconstruction algorithms, VGA scores were indiscernible and were superior to the equally indiscernible Hounsfield reconstructions on parameters translated into Sharpness and Low Contrast Resolution. The two alternative Hounsfield settings were superior with respect to Noise and Artifacts/Beam Hardening.

Conclusion

The study elucidates the possiblity for multiple reconstructions specialized for PMCT conditions, to accommodate the special conditions when working with the deceased. Despite the lack of clear improvements in the tested reconstructions, this study provides an insight into some of the possibilities of improving PMCT quality using reconstruction techniques.

Bone and Tooth: Substrates for determining Drowning: A new diagnostic procedure in forensic medicine Practice?

INTRODUCTION

Diatom tests are rarely used during autopsy to confirm drowning as the cause of death (COD) because of limitations of the current literature involving these techniques. Instead, experts rely on physical examination by the pathologist. Due to interpretive concerns regarding Diatom tests, they are often insufficient in establishing a diagnosis, but offer the potential to be an extremely useful diagnostic tool with further understanding. The aim of study is to optimize "Diatom Tests" for use in forensic medicine in Bosnia and Herzegovina.

METHODS

A randomized prospective experimental study was conducted, using albino Wistar rat models (Rattus norvegicus), at the Veterinary Facility, University of Sarajevo. Thirty-two adult albino rats, were used and distributed into groups as follows: Group A (6 deceased rats with COD other than drowning, but due to mechanical asphyxia, which were then submerged for 1 h after death); Group B (6 deceased rats with COD other than drowning, but due to mechanical asphyxia, which were then submerged for 72 h after death); Group C (6 rats that were immediately autopsied after drowning, with COD determined as drowning); Group D (6 rats that underwent a 48-hour postmortem period after drowning); Group E (COD: drowning, post-mortem 72hrs after death, remained submerged in water until PM). Live algological material was collected for the research of the systematics of algae from the Bosna river, Sarajevo, and transported to the University of Sarajevo (Department of Biology, Faculty of Science). Periphyllon, epiphyllon and epipelon were used to collect phytobenthos. The material was fixed with 4% formalin solution. Laboratory processing of diatoms was performed using the methods described by Hustedt (16). In the process of obtaining pure diatom valves, part of the material is digested with potassium permanganate (KMnO4), sulfuric acid (H2SO4), and oxalic acid (C2H2O4). In the next step, the cleaned diatom valves were mounted in Canadian balsam. A light microscope under 1000x magnification (Best Scope 2020) was used to evaluate and analyze the species. The identification of diatoms was performed using the reference of Cantonati et al (17). The nomenclature of diatom species was performed according to Guiry & Guiry's worldwide electronic internet database.

RESULTS

No diatoms were found in Groups A and B. However, Navicula sp. and Sellaphora sp. cf., were discovered during bone analysis of Group C where rats were immediately autopsied after drowning. Hantzschia amphioxus taxon was present in Group D, which underwent a 48-hour postmortem period after drowning and before samples were taken. In Groups C and D, where drowning was the COD, Diatoma vulgaris i Pinnularia major, Achnanthidium minutissimum i Melosira varians were present in the tooth samples.

CONCLUSION

Optimization of the "Diatom Test" method could potentially lead to its future use as a routine method within experimental settings. This experimental study is a starting point that guides forenscic medicine pracitioners towards the optimization of tests and sampling in cases of unexplained etiology, where preserved soft tissue structures is not available. In these cases, teeth and bones serve as accessible materials for diagnosing COD, alongside standardized nonspecific findings in the absence of organs for micro- and macroanalysis.

Diatom-Positive Cadaver: Drowning or Homicide?

Medico-legal investigations should be performed on all unnatural (homicide, suicide, or accident), unexpected, and suspicious deaths to evaluate the possibility of homicide and ascertain the exact cause of death. However, in some scenarios, burial takes place before an autopsy can be conducted. In such cases, exhumation is performed, which involves excavating the remains of previously buried or cremated individuals for medico-legal investigations. Although the diatom test is a very useful microbiological approach in concluding death by drowning, its reliability remains controversial. Our study presents the case of a cadaver that was exhumed so that medico-legal investigations could be performed to ascertain the exact cause of death. The cadaver was recovered from water but buried before an autopsy could be performed. Upon exhumation, the greater cornu of hyoid bone was fractured with dislocation of the maxilla and mandible. The femur, sternum and clavicle were sent for diatom testing. The diatoms came out positive in the bones; however, the water sample from the gutter didn’t test positive for diatoms. Thus, due to the diatom-negative status of water, diatoms from bones can’t be compared with suspected water samples. Since diatoms in bones can arise as a result of contamination too, death cannot be concluded by drowning. Manual strangulation led to the fracture of the hyoid bone. Asphyxia due to throttling was declared the cause of death. Due to the unreliability of the diatom test in certain cases, other tests should be performed in auxiliary to the diatom test to conclude death by drowning.

Research advances in forensic diatom testing

In forensic practice, it is difficult to determine whether a dead body in the water resulted from drowning or from disposal after death. Diatom testing is currently an important supporting technique for the determination of death by drowning and of drowning sites, even though it is a time-consuming and laborious task. This article reviews the development of diatom testing over the decades and discusses a new method for the potential application of deep learning in diatom testing.