Development of A Micro-CT Scanner with Dual-Energy Option and Endovascular Contrast Agent Administration Protocol for Fetal and Neonatal Virtual Autopsy.

The rate of parental consent for fetal and perinatal autopsy is decreasing, whereas parents are more likely to agree to virtual autopsy by non-invasive imaging methods. Fetal and perinatal virtual autopsy needs high-resolution and good soft-tissue contrast for investigation of the cause of death and underlying trauma or pathology in fetuses and stillborn infants. This is offered by micro-computed tomography (CT), as opposed to the limited resolution provided by clinical CT scanners, and this is one of the most promising tools for non-invasive perinatal postmortem imaging. We developed and optimized a micro-CT scanner with a dual-energy imaging option. It is dedicated to post-mortem CT angiography and virtual autopsy of fetuses and stillborn infants in that the chamber can be cooled down to around 5 °C; this increases tissue rigidity and slows decomposition of the native specimen. This, together with the dedicated gantry-based architecture, attempts to reduce potential motion artifacts. The developed methodology is based on prior endovascular injection of a BaSO4-based contrast agent. We explain the design choices and considerations for this scanner prototype. We give details of the treatment of the optimization of the dual-energy and virtual mono-energetic imaging option that has been based on minimizing noise propagation and maximizing the contrast-to-noise ratio for vascular features. We demonstrate the scanner capabilities with proof-of-concept experiments on phantoms and stillborn piglets.

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.

A review of visualization techniques of post-mortem computed tomography data for forensic death investigations.

Postmortem computed tomography (PMCT) is a standard image modality used in forensic death investigations. Case- and audience-specific visualizations are vital for identifying relevant findings and communicating them appropriately. Different data types and visualization methods exist in 2D and 3D, and all of these types have specific applications. 2D visualizations are more suited for the radiological assessment of PMCT data because they allow the depiction of subtle details. 3D visualizations are better suited for creating visualizations for medical laypersons, such as state attorneys, because they maintain the anatomical context. Visualizations can be refined by using additional techniques, such as annotation or layering. Specialized methods such as 3D printing and virtual and augmented reality often require data conversion. The resulting data can also be used to combine PMCT data with other 3D data such as crime scene laser scans to create crime scene reconstructions. Knowledge of these techniques is essential for the successful handling of PMCT data in a forensic setting. In this review, we present an overview of current visualization techniques for PMCT.

Prevalence of calcified epiglottis in postmortem computed tomography. Is there a correlation to failed endotracheal intubation?

OBJECTIVES: Calcification of the epiglottis is a normal physiological degenerative process, although it can also be a consequence of infection or trauma. There are three possible forensically relevant consequences from epiglottic calcification: misinterpretation as foreign bodies, dysphagia as a major contributing factor to aspiration, and association with difficult intubation or a misplaced ventilation tube. It is the aim of this study (I) to inquire about the prevalence of epiglottic calcification in postmortem CT in general and (II) to investigate whether calcification of the epiglottis is linked to a higher incidence of failed endotracheal intubation. METHODS: We retrospectively analysed 2930 consecutive cases in postmortem CT at the Institute of Forensic Medicine. RESULTS: The prevalence of epiglottic calcification was 4.1%. Higher age and male sex are associated with an increased risk of epiglottic calcification. There was no calcification of the epiglottis in the cases with misplacement of the ventilation tube in the esophagus. CONCLUSIONS: To verify the result of our study, that is, the calcification of the epiglottis is not linked to a higher incidence of failed endotracheal intubation, it might be reasonable to repeat this study with a more representative study population. The high interindividual variations of calcified epiglottis could be used for identification.

The possibility of identifying brain hemorrhage in putrefied bodies with PMCT.

This paper aims to demonstrate that post-mortem CT (PMCT) can locate intracranial hemorrhages, even in decomposed cases. This is of relevance in that post-mortem decomposition is particularly damaging to the brain tissue's consistency, resulting in great difficulties to reliably diagnose and locate intracranial hemorrhages. We searched our case database of the last 11 years to find cases with decomposition of the body, where PMCT and an autopsy had been performed. We identified eleven cases according to these criteria. Postmortem interval ranged from 2 days to 2 weeks, and post-mortem radiological alteration index (RAI) was at or above 49. Eight out of eleven cases showed an intraparenchymal hemorrhage whereas the hemorrhage was extra-axial in the remaining three cases. Autopsy validated the presence of intracranial hemorrhage in all eleven cases, but location could not be confirmed due to liquid state of the brain. PMCT identified and localized intracranial hemorrhages in decomposed bodies, and in all of these cases, autopsy validated their presence. The actual cause of the hemorrhage (e.g. tumor, metastasis, vascular malformation, hypertensive hemorrhage) remained obscure. From this case series, it can be concluded that PMCT may add relevant information pertaining to localization of intracranial hemorrhages in decomposed bodies.

Cardiac conduction devices in the radiologic comparative identification of decedents.

Cardiac conduction devices (CCDs), including pacemakers and implantable cardioverter-defibrillators (ICDs), are implanted in a significant part of the population, especially as the population becomes older. CCDs play an important role in forensic medicine; they are a valuable identification tool as the manufacturer information and unique serial numbers of the device can be matched with the medical records of the person of suspected identity after the device has been removed from the body. Radiological examinations such as X-ray or computed tomography (CT) can illustrate specific CCD features. A series of 12 selected cases is presented to highlight the ability of postmortem CT to visualize CCD details, contributing to possible comparative radiological identification in the case of suspected identity without the requirement of invasive removal. To date, unique patient-specific serial numbers, which are usually not radiopaque, cannot be visualized by imaging. However, a positive match of specific CCD radiologic features combined with other peculiar body findings between ante- and postmortem images can lead to a pure radiologic comparative identification.

Left myocardial wall measurements on postmortem imaging compared to autopsy.

PURPOSE: The aims of this study were, firstly, to determine the relationship of left ventricular wall thickness (LVWT) measurements between postmortem computed tomography (PMCT) and postmortem magnetic resonance imaging (PMMR) and, secondly, to assess the utility of postmortem imaging for LVWT measurements compared to autopsy. MATERIALS AND METHODS: All cases ≥18years old, with postmortem interval ≤4days, cardiac PMCT, PMMR, and full forensic autopsy, were reviewed in our database retrospectively. Exclusion criteria were gas accumulations in the myocardial wall and cardiac trauma. LVWT on PMCT and PMMR was assessed. The measurements were repeated by the same rater after 2months. Autopsy reports were reviewed, and LVWT and pericardial fluid volume measured at autopsy were noted. Pericardial fluid volume >50ml was determined positive for pericardial effusion. RESULTS: A total of 113 cases were included in the study. Twelve cases had pericardial effusion. Intrarater reliability for imaging based LVWT was excellent. LVWT (free wall) was significantly larger on PMCT (18.3mm) compared to PMMR (17.6mm), but these measurements correlated positively. LVWT (anterior wall) was significantly larger on PMMR (15mm) than at autopsy (14mm), and these measurements also correlated positively. Pericardial effusions led to larger differences between PMMR and autopsy measurements, however without statistical significance. DISCUSSION: There exist discrepancies between LVWT as measured on postmortem imaging and at autopsy. Specialists should be aware in order to not misinterpret imaging measurements.

Computationally approximated solution for the equation for Henssge's time of death estimation.

BACKGROUND: Time of death estimation in humans for the benefit of forensic medicine has been successfully approached by Henssge, who modelled body cooling based on measurements of Marshall and Hoare. Thereby, body and ambient temperatures are measured at the death scene to estimate a time of death based on a number of assumptions, such as initial body temperature and stable ambient temperature. While so far, practical use of the method resorted to paper print outs or copies of a nomogram using a ruler, increasingly, users are interested in computer or mobile device applications. We developed a computational solution that has been available online as a web accessible PHP program since 2005. From that, we have received numerous requests not so much to detail our code but to explain how to efficiently approximate the solution to the Henssge equation. METHODS: To solve Henssge's double exponential equation that models physical cooling of a body, it is sufficient to determine a difference term of the equation that will be close to zero for the correct time of death using a discrete set of all sensible possible solutions given that the modelled time frame has practical upper limits. Best post-mortem interval approximation yields minimal difference between equation terms RESULTS: The solution is approximated by solving the equation term difference for a discrete set of all possible time of death intervals that are sensibly found, and by then determining the particular time of death where equation term difference is minimal. CONCLUSIONS: The advantage of a computational model over the nomogram is that the user is also able to model hypothermia and hyperthermia. While mathematically impossible to solve in a straightforward way, solutions to the Henssge equation can be approximated computationally.

Approaching pulmonary fat embolism on postmortem computed tomography.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Nasal Septum Defects Detected on Postmortem Computed Tomography.

Nasal septum defects may have forensic relevance because they are associated with various mechanisms, including trauma and cocaine abuse. Like all human body tissues, the nasal septum may be affected by maggots' infestation during postmortem decomposition. Postmortem computed tomography (PMCT) can reveal small findings and related details. Three cases of early postmortem period and 2 cases of advanced decomposition, where external examination of the nasal cavities and PMCT revealed nasal septum defect, are presented. In the early postmortem period cases, the lesions' edges appeared smoother on PMCT, whereas in the advanced decomposed cases, the edges were irregular and maggots were infested. Postmortem computed tomography can detect nasal septum defects and may help differentiate the preexisting from the postmortem ones based on their edges' radiological appearance. Such findings may indicate possible chronic cocaine abuse (cocaine nose), trauma, or other nasal pathology. It is important to note that such defects may be altered or caused by advanced decomposition.

Death by hanging: a retrospective case-control investigation of the intervertebral disc vacuum phenomenon on PMCT.

During hanging gravitational forces affect the spine. Intervertebral vacuum phenomenon (VP) implies that gas accumulations in the discs are caused by degeneration of the spine and trauma. It was hypothesized that VP detected on postmortem computed tomography (PMCT) has a higher incidence in hanging deaths, which can be correlated to age, degenerative spinal changes and type of hanging (complete-incomplete). Secondly, it was investigated whether the presence of Simon's bleedings is related to hanging type and VP on PMCT. A retrospective hanging case-control study of 72 cases was conducted. PMCT data were evaluated by two observers for the presence of VP and its localization within the thoracic and lumbar discs, and for any degenerative changes of the spine. Autopsy protocols were assessed for the presence of Simon's bleedings during autopsy. VP did not statistically differ among hanging and control cases but it was statistically correlated to complete hanging, increasing age and degenerative spinal changes. Centrally located VP within the discs was correlated to hanging, especially complete hanging, and younger ages, contrary to control cases that showed gas at the disc periphery. Simon's bleedings were correlated with complete hanging and centrally located VP. Centrally located VP within the discs increases the probability for complete hanging, while increasing age and degenerative changes reduce this probability. Intervertebral VP is multifactorial radiological entity. The presence of centrally located VP can indicate that hanging could be considered as an alternative mechanism of death and that great forces and loads may have affected the spine perimortem, especially with decreasing age and when Simon's bleedings are present.

Comparing fist size to heart size is not a viable technique to assess cardiomegaly.

PURPOSE: Several medical textbooks state that a human heart is approximately the size of that person's fist. Stating that a heart has the size of the corpse's fist is thought to signify that the heart size is normal. We formulate two hypotheses that are tested in this article. First, we hypothesize that in cases without cardiomegaly, volumes of the hand and the heart are not significantly different. Second, we hypothesize that in cases of cardiomegaly, the heart volume statistically significantly exceeds that of the hand. MATERIALS AND METHODS: We retrospectively reviewed 130 consecutive postmortem computed tomography datasets from the BLINDED starting from 01/01/2013, covering a period of approximately 3 months. Hands and hearts were segmented and their volumes estimated. We obtained the following information from the postmortem examination reports: age, sex, body length and weight, heart weight, cardiomegaly, and cause of death. RESULTS: When exploring the correlation between mean hand volume and heart volume, only in the group of the females with cardiomegaly (N=8) could a positive, statistically significant correlation be ascertained (Pearson correlation coefficient 0.753, P=.031). DISCUSSION: In this study, we demonstrated that the commonly used idea that a heart larger than the fist of a patient suggests cardiomegaly might be incorrect. Because this perception is commonly used in autopsy reports, it might lead to avoidable errors. Until further studies confirm this hypothesis, this informal measurement should no longer be taught or used.

Thoracic trauma in fatal falls from height - Traumatic pneumopericardium correlates with height of fall and severe injury.

Pneumopericardium (PPC) describes the collection of gas in the pericardial sac. In tension Pneumopericardium (tPPC), this collection of gas may lead to cardiac tamponade. PPC following blunt trauma is considered a rare finding, as reflected by the low number of case reports on the topic. We analyzed the prevalence and pathophysiology of PPC and the associated trauma in 44 cases of falls from height. We retrospectively analyzed postmortem CT data and autopsy reports of fatal falls in the period March 2014-2017. A valid estimation of the height of the fall and a documented impact on an even and hard surface were inclusion criteria. A total of 44 cases were included in the study. We identified PPC in 18 of the 44 cases, and it was associated with an increased height of the fall, alongside aortic, pericardial, and myocardial ruptures. All cases with PPC also presented with bilateral pneumothorax. Five cases presented with a "ballooning" pericardium, indicating tPPC. PPC is a common finding in cases of falls from great heights. Due to a significant correlation with height and thus impact severity, PPC may be used as a reconstructive element in medico-legal investigations. Association with trauma makes PPC a sign of severe thoracic injury in postmortem and clinical radiology.

Fatal Road Traffic Vehicle Collisions With Pedestrian Victims: Forensic Postmortem Computed Tomography and Autopsy Correlation.

Fatal car-to-pedestrian collisions regularly appear in the forensic pathologist's routine, particularly in places of extended urbanization. Postmortem computed tomography has gained an exceptional role to supplement autopsy worldwide, giving information that is supplementary or complimentary to conventional autopsy. In this retrospective study, a total number of 320 findings in a series of 21 pedestrians fatally hit by cars and trucks of both postmortem computed tomography and autopsy were correlated. According to our results, it is best to combine both methods to give well-founded answers to questions pertaining to both collision reconstruction and cause of death.

Case-study of a user-driven prosthetic arm design: bionic hand versus customized body-powered technology in a highly demanding work environment.

BACKGROUND: Prosthetic arm research predominantly focuses on "bionic" but not body-powered arms. However, any research orientation along user needs requires sufficiently precise workplace specifications and sufficiently hard testing. Forensic medicine is a demanding environment, also physically, also for non-disabled people, on several dimensions (e.g., distances, weights, size, temperature, time). METHODS: As unilateral below elbow amputee user, the first author is in a unique position to provide direct comparison of a "bionic" myoelectric iLimb Revolution (Touch Bionics) and a customized body-powered arm which contains a number of new developments initiated or developed by the user: (1) quick lock steel wrist unit; (2) cable mount modification; (3) cast shape modeled shoulder anchor; (4) suspension with a soft double layer liner (Ohio Willowwood) and tube gauze (Molnlycke) combination. The iLimb is mounted on an epoxy socket; a lanyard fixed liner (Ohio Willowwood) contains magnetic electrodes (Liberating Technologies). An on the job usage of five years was supplemented with dedicated and focused intensive two-week use tests at work for both systems. RESULTS: The side-by-side comparison showed that the customized body-powered arm provides reliable, comfortable, effective, powerful as well as subtle service with minimal maintenance; most notably, grip reliability, grip force regulation, grip performance, center of balance, component wear down, sweat/temperature independence and skin state are good whereas the iLimb system exhibited a number of relevant serious constraints. CONCLUSIONS: Research and development of functional prostheses may want to focus on body-powered technology as it already performs on manually demanding and heavy jobs whereas eliminating myoelectric technology's constraints seems out of reach. Relevant testing could be developed to help expediting this. This is relevant as Swiss disability insurance specifically supports prostheses that enable actual work integration. Myoelectric and cosmetic arm improvement may benefit from a less forgiving focus on perfecting anthropomorphic appearance.

Tension pneumopericardium following suicidal stab wounds to the chest.

Pneumopericardium (PPC) and Tension Pneumopericardium (TPPC) refer to collections of gas in the pericardial cavity, the latter resulting in air tamponade and cardiac compromise. Following penetrating chest injuries, PPC and TPPC appear to be uncommon findings associated with a high mortality and correlated with other thoracic trauma. Diagnosis of PPC and TPPC is difficult relying on conventional autopsy alone, while postmortem computed tomography (PMCT) shows a high sensitivity for the detection of internal gas collections. Possibly due to difficulty in detection, PPC and TPPC have not been discussed from a forensic point of view and many lethal cases of PPC and TPPC might have been missed in medicolegal investigations. In this report, we present a case with suicidal, penetrating stab wounds to the chest resulting in a TPPC with lethal air tamponade documented by PMCT.

Comparative radiologic identification with standardized single CT images of the paranasal sinuses-Evaluation of inter-rater reliability.

The aim of this study was to assess the reproducibility of a standardized image for personal identification (SIPI), used in the comparative analysis of paranasal sinuses, and test the effect of inaccurate reformation of the SIPI on suitability for comparative identification. Five raters with different professional backgrounds independently reformatted SIPIs from ten post-mortem head CTs. Inter-rater, intra-rater agreement as well angular deviations between reformatted SIPI images and reference SIPI images were calculated. Second, raters assessed the suitability of 70 accurately and inaccurately reformatted SIPIs for identification with a 4-point Likert scale. Inter-rater agreement as well as levels of significance regarding image suitability were calculated. Inter-rater agreement regarding reproducibility of SIPI reformation was excellent (inter-rater correlation coefficient (ICC) 0.9995, intra-rater ICC 0.9983). Deviation between the angular dimensions of the reformatted SIPIs and the reference SIPIs was ≤1° in 94% of all 300 measurements. Inter-rater agreement regarding the effect of inaccurate SIPI reformation on suitability for comparative identification was fair (ICC 0.6809). There was no statistically significant difference between raters' evaluation of image suitability (p=0.9755). This study shows that the standardized image for personal identification can be accurately reformatted by different raters with varying professional backgrounds. In addition, raters agree that inaccurately reformatted SIPIs are still suitable for comparative identification in the majority of cases.

Automatic detection of hemorrhagic pericardial effusion on PMCT using deep learning - a feasibility study.

Post mortem computed tomography (PMCT) can be used as a triage tool to better identify cases with a possibly non-natural cause of death, especially when high caseloads make it impossible to perform autopsies on all cases. Substantial data can be generated by modern medical scanners, especially in a forensic setting where the entire body is documented at high resolution. A solution for the resulting issues could be the use of deep learning techniques for automatic analysis of radiological images. In this article, we wanted to test the feasibility of such methods for forensic imaging by hypothesizing that deep learning methods can detect and segment a hemopericardium in PMCT. For deep learning image analysis software, we used the ViDi Suite 2.0. We retrospectively selected 28 cases with, and 24 cases without, hemopericardium. Based on these data, we trained two separate deep learning networks. The first one classified images into hemopericardium/not hemopericardium, and the second one segmented the blood content. We randomly selected 50% of the data for training and 50% for validation. This process was repeated 20 times. The best performing classification network classified all cases of hemopericardium from the validation images correctly with only a few false positives. The best performing segmentation network would tend to underestimate the amount of blood in the pericardium, which is the case for most networks. This is the first study that shows that deep learning has potential for automated image analysis of radiological images in forensic medicine.