How low can we go? CT dose reduction in the assessment of the medial clavicular epiphysis in forensic age estimation: a prospective postmortem CT study.

BACKGROUND: Projection radiography and, more recently, computed tomography (CT) play an important role in forensic age estimation. Both in terms of general criminal responsibility and government regulations concerning refugee care, it is important to differentiate correctly between youths and adults. A disadvantage of age estimation in CT is the ionizing radiation exposure. PURPOSE: To investigate how far the CT dose can be reduced without losing diagnostic confidence in assessing the different stages of ossification of the medial clavicle. MATERIAL AND METHODS: We prospectively scanned 25 postmortem cases with a fixed parameters protocol (FPP) and a care dose modulation protocol (CDMP) for different scan parameters. Two radiologists assessed the diagnostic image quality using a 5-point Likert scale. Inter-reader agreement was evaluated with Cohen's kappa. Differences in doses between FPP and CDMP were assessed with the one-tailed t-test. RESULTS: The best combination of diagnostic image quality and lowest radiation dose was obtained using a CDMP with 100 kV and 40 mAs and an FPP with 100 kV and 30 mAs. Doses for 120 kV were significantly higher (one-tailed P < 0.001). The diagnostic image quality for 80 kV was insufficient overall. DISCUSSION: Our results confirm that CT imaging at 100 kV allows a sufficient image quality that is diagnostic for age estimation in the ossification of the medial clavicle.

Pseudolesion in the right parafissural liver parenchyma on CT: The base is found in embryology and collagen content.

BACKGROUND: Computed tomography (CT) images of livers may show a hypo-attenuated structure alongside the falciform ligament, which can be a focal fatty pseudolesion and can mimic a malignancy. The preferred location is on the right parafissural site, ventral in segment IVa/b. The etiology is not clear, nor is it known how the histology of this location develops. These are evaluated in this study. METHODS: 40 adult cadavers with autopsy and / or postmortem CT in a university hospital and a forensic center were included. Liver biopsies were taken at the left side of the falciform ligament as control, and at the right side as the possible precursor of a pseudolesion; these were examined for collagen and fat content. Cadavers with steatotic (>5% fat) or fibrotic (>2% collagen) control samples were excluded. RESULTS: Significantly more collagen was present in the right parafissural liver parenchyma: median 0.68% (IQR: 0.32-1.17%), compared to the left side 0.48% (IQR: 0.21-0.75%) (p 0.008), with equal fat content and CT attenuation values. The etiophysiology goes back to the demise of the umbilical venes in the early embryonic and neonatal period. CONCLUSIONS: The right parafissural area contains more collagen and an equal amount of fat compared to the control left side. This supports the hypothesis of delayed, 'third' inflow: the postnatal change in blood supply from umbilical to portal leaves the downstream parafissural area hypoperfused leading to hypoxia which in turn results in collagen accumulation and the persistence of paraumbilical veins of Sappey.

Standardized medical image registration for radiological identification of decedents based on paranasal sinuses.

Image registration software is frequently used in clinical radiology, e.g., for follow-up diagnosis. To a certain extent, the radiological identification of decedents (RadID) is comparable to a clinical follow-up diagnosis, in that two datasets from different dates are compared in terms of their anatomical characteristics (e.g., paranasal sinuses) or surgical implants. Due to the increasing use of computed tomography (CT) for head examinations in clinical radiology and the increased use of postmortem CT (PMCT) in forensic imaging, the comparison of three-dimensional (3D) clinical CT (termed as antemortem CT (AMCT) in this article) and PMCT datasets for RadID is becoming increasingly practical. In particular, the comparison of paranasal sinuses in AMCT and PMCT imaging is considered a suitable and reliable modality for RadID. However, previous publications regarding RadID based on comparisons of 3D datasets have not considered the implementation of image registration to provide software-side support for RadID. This article demonstrates and evaluates the use of a standard medical image registration procedure for RadID by comparing paranasal sinuses.

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.

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.

A Fatal Case of a Ruptured Cerebral Aneurysm Detected by Postmortem Computed Tomography Angiography Using a New Contrast-Medium Solution.

Forensic autopsy is still the criterion standard in legal investigations. Currently, notable transformation is occurring because postmortem imaging is being increasingly endorsed. This article highlights the effectiveness of postmortem computed tomography angiography by using a new contrast medium mixture as a solitary tool to define the cause and manner of death in a ruptured cerebral aneurysm case. Based on the imaging results, autopsy was not mandated and the case was closed.

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.

Postmortem computed tomography and magnetic resonance imaging facilitates forensic autopsy in a fatal case of poisoning with formic acid, diphenhydramine, and ethanol.

A case of fatal poisoning by ingesting formic acid, diphenhydramine, and ethanol by a 25-year-old woman who committed suicide is presented. Prior to autopsy, postmortem computed tomography and postmortem magnetic resonance tomography were performed and revealed severe damage to the stomach, the left thoracic wall, and parts of the liver. Imaging detected acid-induced fluid-fluid level within the thoracic cavity (fat-equivalent fluid and necrotic pleural effusion). This case report illustrates that postmortem cross-sectional imaging may facilitate dissection of severely damaged or complex regions, and may provide additional information compared to autopsy and toxicological examinations alone.

Pulmonary thromboembolism on unenhanced postmortem computed tomography: Feasibility and findings.

PURPOSE: The purpose of this study was to evaluate the feasibility of diagnosing fatal pulmonary thromboembolism (PTE) with unenhanced postmortem computed tomography (PMCT). MATERIALS AND METHODS: Twelve cases with autopsy confirmed PTE and matched controls (n=19) were retrospectively examined for PTE signs on PMCT. The following variables were evaluated: edema of the lower extremities (areal and Hounsfield Unit measurements) and observer dependent patterns of the morphology of the sedimentation in the pulmonary arteries and trunk. RESULTS: The median absolute difference between the areal measurements of the right and left lower leg and thigh and the attenuation of the popliteal adipose tissue did not differ significantly between the groups. In contrast, the categorical assessment of soft tissue edema in the lower extremities was significantly different. A statistically significant difference could also be found in the shape of the vascular content within the pulmonary trunk and arteries. CONCLUSION: PTE may be assessed on unenhanced PMCT using diagnostic clues such as a distinct pattern of the pulmonary artery content and the presence of perivascular edema in the lower extremities.

Postmortem magnetic resonance imaging: Reproducing typical autopsy heart measurements.

PURPOSE: The aim of this study was to evaluate the utility of cardiac postmortem magnetic resonance (PMMR) to perform routine measurements of the ventricular wall thicknesses and the heart valves and to assess if imaging measurements are consistent with traditional autopsy measurements. METHODS: In this retrospective study, 25 cases with cardiac PMMR and subsequent autopsy were included. The thicknesses of the myocardial walls as well as the circumferences of all heart valves were measured on cardiac PMMR and compared to autopsy measurements. Paired samples T-test and the Wilcoxon-Signed rank test, were used to compare autopsy and cardiac PMMR measurements. For exploring correlations, the Pearson's Correlation coefficient and the Spearman's Rho test were used. RESULTS: Cardiac PMMR measurements of the aortic and pulmonary valve circumferences showed no significant differences from autopsy measurements. The mitral and tricuspid valves circumferences differed significantly from autopsy measurements. Left myocardial and right myocardial wall thickness also differed significantly from autopsy measurements. Left and right myocardial wall thickness, and tricuspid valve circumference measurements on cardiac PMMR and autopsy, correlated strongly and significantly. CONCLUSION: Several PMMR measurements of cardiac parameters differ significantly from corresponding autopsy measurements. However, there is a strong correlation between cardiac PMMR measurements and autopsy measurements in the majority of these parameters. It is important to note that myocardial walls are thicker when measured in situ on cardiac PMMR than when measured at autopsy. Investigators using post-mortem MR should be aware of these differences in order to avoid false diagnoses of cardiac pathology based on cardiac PMMR.

A fatal case of electrocution with unique forensic radiological postmortem findings.

PURPOSE: Documentation of forensic radiological observations in postmortem imaging of electrical injuries is not common yet and is less prevalent compared to other forms of burn injuries. However, electrical injuries have high morbidity and mortality. The objective of this case report was the visualization and evaluation of unique electrocution-related injuries by postmortem contrast and non-contrast enhanced imaging compared to a forensic autopsy. METHODS: Forensic imaging included whole-body postmortem computed tomography (PMCT), PMCT-angiography (PMCTA), postmortem magnetic resonance tomography (PMMR), and PMMR-angiography (PMMRA). Initial external inspection and subsequent autopsy were performed. RESULTS: Imaging results revealed intestinal mucosal pathologies, particularly of the gastric vascular integrity and remarkable rhabdomyolysis of the striated muscles of the extremities. Furthermore, PMCT and PMCTA revealed a hepatic lesion with perihepatic free fluid. The results from external inspection and autopsy correlated to the well-known pathologies of electrocution in the course of a high-voltage incident. CONCLUSION: Postmortem imaging visualized electrocution-related injuries and aided substantially in the medico-legal investigation. These findings, particularly of the rhabdomyolysis in magnetic resonance tomography, may support the future image interpretation of cases with electrical injuries-in the living and the deceased.

Systematic analysis of the radiologic findings of aortic dissections on unenhanced postmortem computed tomography.

The aim of this study was to evaluate the diagnostic criteria and to identify the radiological signs (derived from known radiological signs) for the detection of aortic dissections using postmortem computed tomography (PMCT). Thirty-three aortic dissection cases were retrospectively evaluated; all underwent PMCT and autopsy. The images were initially evaluated independently by two readers and were subsequently evaluated in consensus. Known radiological signs, such as dislocated calcification and an intimomedial flap, were identified. The prevalence of the double sedimentation level in the true and false lumen of the dissected aorta was assessed and defined as a postmortem characteristic sign of aortic dissection. Dislocated calcification was detected in 85% of the cases with aortic calcification; whereas in 54% of the non-calcified aortas, the intimomedial flap could also be recognized. Double sedimentation was identified in 16/33 of the cases. Overall, in 76% (25/33) of the study cases, the described signs, which are indicative for aortic dissection, could be identified. In this study, three diagnostic criteria of aortic dissection were identified using non-enhanced PMCT images of autopsy-confirmed dissection cases.

The correlation of epicardial adipose tissue on postmortem CT with coronary artery stenosis as determined by autopsy.

The goal of this study was to assess whether epicardial and paracardial adipose tissue volumes, as determined by computed tomography (CT), correlate with coronary artery stenosis as determined by autopsy. The postmortem CT data and autopsy findings of 116 adult human decedents were retrospectively compared. Subjects were classified into three groups according to their degree of coronary artery stenosis: ≥50, <50%, and no stenosis. Epicardial and paracardial adipose tissue volumes were calculated based on manual segmentation after threshold based masking. In addition, epicardial adipose tissue thickness was measured using a caliper. All three parameters (thickness of epicardial fat and volumes of both epicardial and paracardial fat) were compared among the three groups and correlated with the degree of coronary artery stenosis. The group with no coronary artery stenosis showed the lowest mean values of epicardial adipose tissue volume, while the coronary artery stenosis ≥50 % group showed the highest volume. All measured variables (thickness of epicardial fat and volumes of both epicardial and paracardial fat) correlated significantly with the grade of coronary artery stenosis, even after controlling for BMI, however, epicardial adipose tissue volume exhibited the strongest correlation. This study reveals that there is an association between the degree of coronary artery stenosis and the amount of epicardial fat tissue: The larger the volume of epicardial fat, the higher the degree of coronary artery stenosis.

Racking the brain: detection of cerebral edema on postmortem computed tomography compared with forensic autopsy.

PURPOSE: The purpose of this study was to compare postmortem computed tomography with forensic autopsy regarding their diagnostic reliability of differentiating between pre-existing cerebral edema and physiological postmortem brain swelling. MATERIALS AND METHODS: The study collective included a total of 109 cases (n=109/200, 83 male, 26 female, mean age: 53.2 years) and were retrospectively evaluated for the following parameters (as related to the distinct age groups and causes of death): tonsillar herniation, the width of the outer and inner cerebrospinal fluid spaces and the radiodensity measurements (in Hounsfield Units) of the gray and white matter. The results were compared with the findings of subsequent autopsies as the gold standard for diagnosing cerebral edema. p-Values <0.05 were considered statistically significant. RESULTS: Cerebellar edema (despite normal postmortem swelling) can be reliably assessed using postmortem computed tomography and is indicated by narrowed temporal horns and symmetrical herniation of the cerebellar tonsils (p<0.001). There was a significant difference (p<0.001) between intoxication (or asphyxia) and all other causes of death; the former causes demonstrated higher deviations of the attenuation between white and gray matter (>20 Hounsfield Units), and the gray to white matter ratio was >1.58 when leukoencephalopathy was excluded. CONCLUSIONS: Despite normal postmortem changes, generalized brain edema can be differentiated on postmortem computed tomography, and white and gray matter Hounsfield measurements help to determine the cause of death in cases of intoxication or asphyxia. Racking the brain about feasible applications for a precise and reliable brain diagnostic forensic radiology method has just begun.

Smaller but denser: postmortem changes alter the CT characteristics of subdural hematomas.

PURPOSE: The aim of this study was to investigate if (1) the volume of subdural hematomas (SDH), midline shift, and CT density of subdural hematomas are altered by postmortem changes and (2) if these changes are dependent on the postmortem interval (PMI). MATERIALS AND METHODS: Ante mortem computed tomography (AMCT) of the head was compared to corresponding postmortem CT (PMCT) in 19 adults with SDH. SDH volume, midline shift, and hematoma density were measured on both AMCT and PMCT and their differences assessed using Wilcoxon-Signed Rank Test. Spearman's Rho Test was used to assess significant correlations between the PMI and the alterations of SDH volume, midline shift, and hematoma density. RESULTS: Mean time between last AMCT and PMCT was 109 h, mean PMI was 35 h. On PMCT mean midline displacement was decreased by 57% (p < 0.001); mean SDH volume was decreased by 38% (p < 0.001); and mean hematoma density was increased by 18% (p < 0.001) in comparison to AMCT. There was no correlation between the PMI and the normalization of the midline shift (p = 0.706), the reduction of SDH volume (p = 0.366), or the increase of hematoma density (p = 0.140). CONCLUSIONS: This study reveals that normal postmortem changes significantly affect the extent and imaging characteristics of subdural hematoma and may therefore affect the interpretation of these findings on PMCT. Radiologists and forensic pathologists who use PMCT must be aware of these phenomena in order to correctly interpret PMCT findings in cases of subdural hemorrhages.

Postmortem angiography in computed tomography and magnetic resonance imaging in a case of fatal hemorrhage due to an arterio-venous malformation in the brain.

Autopsy is the traditional gold standard for determining the cause and manner of death in a forensic death investigation. However, postmortem imaging plays an ever-growing role in preliminary examination, even replacing conventional autopsy in some cases. This case report presents a case of massive intra-axial brain hemorrhage due to an arterio-venous malformation. The cause and manner of death were exclusively determined by postmortem radiology. Based on radiological findings, the autopsy was considered redundant and cancelled by the public prosecutor.

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.

Postmortem CT angiography: capabilities and limitations in traumatic and natural causes of death.

Whole-body postmortem computed tomographic (CT) angiography is a promising new development in forensic radiology that has the potential to improve vascular and soft-tissue imaging beyond levels currently achievable with unenhanced postmortem CT. Postmortem access to the vascular system and injection of contrast medium are different from those steps in clinical (antemortem) radiology. Because there is no circulation in a corpse that could transport or dilute a contrast medium, the injection must be performed by using a roller pump to fill the vasculature (arterial and venous) with a mixture of a water-soluble iodized contrast medium and polyethylene glycol. In contrast to a classic autopsy, postmortem CT angiography is a minimally invasive procedure. It allows the diagnosis of vascular lesions without the disruption or destruction of anatomic structures, which could result in a loss of evidence in a criminal investigation. Furthermore, postmortem CT angiography facilitates the display of vascular pathologic conditions in areas that are not typically covered with autopsy alone, such as the craniocervical junction and the small pelvis. Therefore, postmortem CT angiography adds substantial value to the classic forensic autopsy; cross-sectional data can be reevaluated objectively at any time and are fully reproducible as counterexpertise, which is as useful in the fields of forensic medicine and pathology as in clinical research. Familiarity with the capabilities of postmortem CT angiography may help radiologists working with forensic cases improve their diagnostic performance.

Imaging in forensic radiology: an illustrated guide for postmortem computed tomography technique and protocols.

Forensic radiology is a new subspecialty that has arisen worldwide in the field of forensic medicine. Postmortem computed tomography (PMCT) and, to a lesser extent, PMCT angiography (PMCTA), are established imaging methods that have replaced dated conventional X-ray images in morgues. However, these methods have not been standardized for postmortem imaging. Therefore, this article outlines the main approach for a recommended standard protocol for postmortem cross-sectional imaging that focuses on unenhanced PMCT and PMCTA. This review should facilitate the implementation of a high-quality protocol that enables standardized reporting in morgues, associated hospitals or private practices that perform forensic scans to provide the same quality that clinical scans provide in court.

Times have changed! Forensic radiology--a new challenge for radiology and forensic pathology.

OBJECTIVE: The ongoing development of imaging and the recent integration of cross-sectional imaging methods into the medicolegal workflow have resulted in an increasing number of forensic institutes acquiring dedicated CT and MRI scanners. The purpose of this article is to evaluate the different aspects of postmortem imaging and to detail the necessary cooperation between radiologists and forensic pathologists for mutual learning and accurate science to form a new subspecialty: forensic radiology. CONCLUSION; Forensic radiology must integrate the expertise of forensic pathologists and radiologists. The challenge is to unite these two disciplines first by direct and intense communications and second by a basic understanding of forensic pathology by radiologists as well as a foundational knowledge of postmortem imaging by forensic pathologists, in combination with the establishment of educational and reporting guidelines.