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.

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.

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.

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.

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.

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.

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.

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.

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.

Forensic 3D Visualization of CT Data Using Cinematic Volume Rendering: A Preliminary Study.

OBJECTIVE: The 3D volume-rendering technique (VRT) is commonly used in forensic radiology. Its main function is to explain medical findings to state attorneys, judges, or police representatives. New visualization algorithms permit the generation of almost photorealistic volume renderings of CT datasets. The objective of this study is to present and compare a variety of radiologic findings to illustrate the differences between and the advantages and limitations of the current VRT and the physically based cinematic rendering technique (CRT). MATERIALS AND METHODS: Seventy volunteers were shown VRT and CRT reconstructions of 10 different cases. They were asked to mark the findings on the images and rate them in terms of realism and understandability. RESULTS: A total of 48 of the 70 questionnaires were returned and included in the analysis. On the basis of most of the findings presented, CRT appears to be equal or superior to VRT with respect to the realism and understandability of the visualized findings. Overall, in terms of realism, the difference between the techniques was statistically significant (p < 0.05). Most participants perceived the CRT findings to be more understandable than the VRT findings, but that difference was not statistically significant (p > 0.05). CONCLUSION: CRT, which is similar to conventional VRT, is not primarily intended for diagnostic radiologic image analysis, and therefore it should be used primarily as a tool to deliver visual information in the form of radiologic image reports. Using CRT for forensic visualization might have advantages over using VRT if conveying a high degree of visual realism is of importance. Most of the shortcomings of CRT have to do with the software being an early prototype.

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.

Fatal bronchovascular fistula after lobectomy visualized through postmortem computed tomography angiography: A case report.

False aneurysm of the pulmonary artery complicated by bronchovascular fistula formation represents a rare life threating condition. We report a case of fatal hemoptysis after formation of a bronchial fistula in the late postoperative period after sleeve lobectomy. Cause of death was determined by external postmortem examination, post mortem computed tomography (PMCT) and angiography (PMCTA) without conventional autopsy.

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.

Accuracy of non-contrast PMCT for determining cause of death.

The aim of this study was (1) to compare levels of accuracy regarding the categorization of causes of death between non-contrast post-mortem computed tomography (PMCT) and the final forensic report as well as between autopsy and the final forensic report, and (2) to assess levels of confidence regarding the categorization of causes of death after non-contrast PMCT and after autopsy. This prospective study was conducted over a 5 month period during which 221 cases were admitted to our institute for forensic investigations. Whole-body PMCT and forensic autopsy were performed in every case. Of these, 101 cases were included in the final study population. Inclusion criteria were: (1) age > 18 years, (2) presence of at least one of the two principal investigators at the time of admission. One radiologist and one forensic pathologist independently read all PMCT datasets using a report template. Cause of death category and confidence levels were determined by consensus. Forensic autopsy was performed by two forensic pathologists; both unblinded to imaging results. Both post-imaging and post-autopsy cause of death categorization were compared against the final cause of death, as stated in the forensic expert report, which included findings from histology and/or toxicology. Accuracy of post-imaging cause of death categorization in reference to the final cause of death category was substantial (82%, 83/101 cases, Kappa 0.752). Accuracy of post-autopsy cause of death categorization in reference to the final cause of death category was near perfect (89%, 90/101 cases, Kappa 0.852). Post-imaging sensitivity and specificity regarding the categorization of causes of death were 82% and 97%, respectively. Post-autopsy sensitivity and specificity regarding the categorization of causes of death were 89% and 98%, respectively. There was a high consistency between the accuracy of post-imaging cause of death categorization and post-imaging levels of confidence. There was less consistency between accuracy of post-autopsy cause of death categorization and post-autopsy levels of confidence. In this study categorization of causes of death based on non-contrast enhanced PMCT alone, and on PMCT and macroscopic autopsy together, proved to be consistent with the final cause of death-category as determined based on all available information including PMCT, autopsy, and (if available) histology and/or toxicology in more than 82% and 89% of all cases, respectively. There was higher consistency between levels of confidence and accuracy of causes of death categorization was higher post-imaging than post-autopsy. These results underline the fact that the diagnostic potential of PMCT goes beyond the assessment of trauma cases.

Differentiation of hemopericardium due to ruptured myocardial infarction or aortic dissection on unenhanced postmortem computed tomography.

The aim of the study was to evaluate unenhanced postmortem computed tomography (PMCT) in cases of non-traumatic hemopericardium by establishing the sensitivity, specificity and accuracy of diagnostic criteria for the differentiation between aortic dissection and myocardial wall rupture due to infarction. Twenty six cases were identified as suitable for evaluation, of which ruptured aortic dissection could be identified as the underlying cause of hemopericardium in 50% of the cases, and myocardial wall rupture also in 50% of the cases. All cases underwent a PMCT and 24 of the cases also underwent one or more additional examinations: a subsequent autopsy, or a postmortem magnetic resonance (PMMR), or a PMCT angiography (PMCTA), or combinations of the above. Two radiologists evaluated the PMCT images and classified each case as "aortic dissection", "myocardial wall rupture" or "undetermined". Quantification of the pericardial blood was carried out using segmentation techniques. 17 of 26 cases were correctly identified, either as aortic dissections or myocardial ruptures, by both readers. 7 of 13 myocardial wall ruptures were identified by both readers, whereas both readers identified correctly 10 of 13 aortic dissection cases. Taking into account the responses of both readers, specificity was 100% for both causes of hemopericardium and sensitivity as well as accuracy was higher for aortic dissections than myocardial wall ruptures (72.7% and 87.5% vs 53.8% and 75% respectively). Pericardial blood volumes were constantly higher in the aortic dissection group, but a statistical significance of these differences could not be proven, since the small count of cases did not allow for statistical tests. This study showed that diagnostic criteria for the differentiation between ruptured aortic dissection and myocardial wall rupture due to infarction are highly specific and accurate.

Automatic entry point planning for robotic post-mortem CT-based needle placement.

INTRODUCTION: Post-mortem computed tomography guided placement of co-axial introducer needles allows for the extraction of tissue and liquid samples for histological and toxicological analyses. Automation of this process can increase the accuracy and speed of the needle placement, thereby making it more feasible for routine examinations. To speed up the planning process and increase safety, we developed an algorithm that calculates an optimal entry point and end-effector orientation for a given target point, while taking constraints such as accessibility or bone collisions into account. TECHNIQUE: The algorithm identifies the best entry point for needle trajectories in three steps. First, the source CT data is prepared and bone as well as surface data are extracted and optimized. All vertices of the generated surface polygon are considered to be potential entry points. Second, all surface points are tested for validity within the defined hard constraints (reachability, bone collision as well as collision with other needles) and removed if invalid. All remaining vertices are reachable entry points and are rated with respect to needle insertion angle. Third, the vertex with the highest rating is selected as the final entry point, and the best end-effector rotation is calculated to avoid collisions with the body and already set needles. DISCUSSION: In most cases, the algorithm is sufficiently fast with approximately 5-6 s per entry point. This is the case if there is no collision between the end-effector and the body. If the end-effector has to be rotated to avoid collision, calculation times can increase up to 24 s due to the inefficient collision detection used here. In conclusion, the algorithm allows for fast and facilitated trajectory planning in forensic imaging.

Computer-assisted virtual autopsy using surgical navigation techniques.

UNLABELLED: OBJECTIVE; Virtual autopsy methods, such as postmortem CT and MRI, are increasingly being used in forensic medicine. Forensic investigators with little to no training in diagnostic radiology and medical laypeople such as state's attorneys often find it difficult to understand the anatomic orientation of axial postmortem CT images. We present a computer-assisted system that permits postmortem CT datasets to be quickly and intuitively resliced in real time at the body to narrow the gap between radiologic imaging and autopsy. CONCLUSION: Our system is a potentially valuable tool for planning autopsies, showing findings to medical laypeople, and teaching CT anatomy, thus further closing the gap between radiology and forensic pathology.