Deep Learning-Based Diagnosis of Fatal Hypothermia Using Post-Mortem Computed Tomography.

In forensic medicine, fatal hypothermia diagnosis is not always easy because findings are not specific, especially if traumatized. Post-mortem computed tomography (PMCT) is a useful adjunct to the cause-of-death diagnosis and some qualitative image character analysis, such as diffuse hyperaeration with decreased vascularity or pulmonary emphysema, have also been utilized for fatal hypothermia. However, it is challenging for inexperienced forensic pathologists to recognize the subtle differences of fatal hypothermia in PMCT images. In this study, we developed a deep learning-based diagnosis system for fatal hypothermia and explored the possibility of being an alternative diagnostic for forensic pathologists. An in-house dataset of forensic autopsy proven samples was used for the development and performance evaluation of the deep learning system. We used the area under the receiver operating characteristic curve (AUC) of the system for evaluation, and a human-expert comparable AUC value of 0.905, sensitivity of 0.948, and specificity of 0.741 were achieved. The experimental results clearly demonstrated the usefulness and feasibility of the deep learning system for fatal hypothermia diagnosis.

Diagnosing Drowning in Postmortem CT Images Using Artificial Intelligence.

Imaging features of the lung in postmortem computed tomography (CT) scans have been reported in drowning cases. However, it is difficult for forensic pathologists with limited experience to distinguish subtle differences in CT images. In this study, artificial intelligence (AI) with deep learning capability was used to diagnose drowning in postmortem CT images, and its performance was evaluated. The samples consisted of high-resolution CT images of the chest of 153 drowned and 160 non-drowned bodies captured by an 8- or 64-row multislice CT system. The images were captured with an image slice thickness of 1.0 mm and spacing of 30 mm, and 28 images were typically captured. A modified AlexNet was used as the AI architecture. The output result was the drowning probability for each component image. To evaluate the performance of the proposed model, the area under the receiver operating characteristic curve (AUC) was analyzed, and the AUC value of 0.95 was obtained. This indicates that the proposed AI architecture is a useful and powerful complementary testing approach for diagnosing drowning in postmortem CT images. Notably, the accuracy was 81% (62/77) for cases in which resuscitation was performed, and 92% (216/236) for cases in which resuscitation was not attempted. Therefore, the proposed AI method should not be used to diagnose the cause of death when aggressive cardiopulmonary resuscitation was performed. Additionally, because honeycomb lungs are likely to exhibit different morphologies, emphysema cases should also be treated with caution when the proposed AI method is used to diagnose drowning.

Diagnostic Accuracy of Liver Damage Based on Postmortem Computed Tomography Findings in High-Energy Trauma.

The liver is an organ that is frequently injured by blunt trauma. In clinical medicine, contrast-enhanced computed tomography (CT) is useful for diagnosing liver damage. However, detection of liver injury is difficult with postmortem CT (PMCT) that does not use contrast media. This study aims to identify findings that are useful for diagnosing liver injury with PMCT. This study included 97 high-energy trauma cases that underwent both PMCT without contrast and forensic autopsy between July 2009 and November 2020. PMCT findings in and around the liver in cases of liver injury were collected. The diagnostic accuracy of each finding was calculated. Of 97 cases, 62 had liver injury on autopsy. PMCT detected hepatic surface gas in 31 cases, intrahepatic focal gas in 19 cases, high-density fluid accumulation around the liver in 12 cases, and fracture of a right lower (9th-12th) rib in 48 cases. Abnormal PMCT findings in and around the liver had insufficient diagnostic sensitivity, ranging from 19.4% to 38.7%. By contrast, the finding of a right lower rib fracture was more sensitive for suspected liver injury. Our results indicate that abdominal liver findings (hepatic surface gas, intrahepatic focal gas, and high-density fluid accumulation around the liver) are of limited utility for the diagnosis of liver injury, whereas a right lower rib fracture is a useful indirect finding.

Block-like and cast-like hyperdense areas in the right heart cavities on post-mortem CT strongly suggest the presence of intracardiac blood clots at autopsy.

OBJECTIVE: To classify the types of hyperdense areas in the heart cavities on post-mortem CT (PMCT) and compare them according to the presence of blood clots in the heart cavities at forensic autopsy. METHODS: One hundred and twelve cases with CT images taken before forensic autopsy were evaluated. The presence and shape of hyperdense areas in the right or left heart cavities were retrospectively evaluated on PMCT images and were classified into four types (block-like, cast-like, fluid level-like, and unclear). The presence of blood clots was confirmed when there were clots in the heart cavities at forensic autopsy. RESULTS: Of the 112 cases, 57 exhibited blood clots in the heart cavities at forensic autopsy. The hyperdense areas in the right heart cavities on PMCT in 57 cases exhibiting blood clots at forensic autopsy were classified as follows: block-like, 32; fluid level-like, 4; cast-like, 17; and unclear, 4. The sensitivity of block-like and cast-like hyperdense areas in the right heart cavities on PMCT for the presence of clots in the heart cavities at forensic autopsy was 86% (95% confidence interval [CI]: 74-94%); the corresponding specificity, PPV, and NPV were 95% (95% CI: 85-99%), 94% (95% CI: 84-99%), and 87% (95% CI: 75-94%), respectively. CONCLUSION: Block-like and cast-like hyperdense areas in the right heart cavities on PMCT predicted the presence of intracardiac blood clots at forensic autopsy. KEY POINTS: • Clinical radiologists likely have no experience of interpreting findings of blood clots on post-mortem CT (PMCT). • The appearance of blood clots on PMCT provides important clues for diagnosing the cause and process of death. • The shapes of the hyperdense areas in the heart cavities were classified into four types, and two of these types could be used to predict the presence of blood clots in the heart cavities at forensic autopsy.

Evaluation of the Utility of Mitochondrial DNA Testing in Personal Identification Work in the Great East Japan Earthquake of 2011.

Although the Great East Japan Earthquake occurred on March 11, 2011, identification of victims is still ongoing. Typically, mitochondrial DNA (mtDNA) is performed when it is difficult to identify an individual using nuclear DNA. In Japan, samples from criminal investigations are subjected to nuclear DNA testing at the Scientific Research Institute belonging to each prefectural police headquarters, while all mtDNA tests were originally conducted at the National Research Institute of Police Science. However, the appraisal work using mtDNA became more time-consuming as the number of target samples increased. Because our department is capable of performing mtDNA testing, the Miyagi Prefectural Police requested that our department perform mtDNA testing. Specifically, we focused on 16 individuals as putative candidates for 11 unidentified human remains; efforts to identify these remains were performed using samples from 20 relatives. These efforts positively identified six victims. This included confirmation that one corpse had originally been identified incorrectly. Although disasters of a similar scale can strike Japan again, there are limited facilities that can consistently perform mtDNA testing. Expensive sequencing machines and properly trained operators are essential for mtDNA testing, but they cannot be established at the forensic departments of all medical schools. There is thus an urgent need to establish core facilities at appropriate sites, such as Tohoku University in the Tohoku Region, to build a mtDNA testing system suitable for the aftermath of any disaster.

Postmortem Computed Tomographic Analysis of Death Caused by Oral Drug Intoxication.

Traditional autopsy has changed little in the past century. In Japan, the rate of forensic autopsy in cases of unusual death is very low. Therefore, multi-slice computed tomography (CT) has been used to obtain imaging data instead of or in addition to autopsy in suspicious forensic cases. In our institute, postmortem multi-slice CT has been performed since 2009, and by 2014 there were over 1,000 cases. Our extensive experience with postmortem CT shows that in many cases of death by drug overdose, stomach contents exhibit high X-ray absorption. This article reviews the relationship between CT findings of stomach contents and toxicological analysis results in 23 cases of death by drug overdose. All cases (12 females and 11 males, aged 44 ± 11 years) known to have orally ingested drugs were included in this study. We assessed the slices of all stomach areas on consecutive axial CT images. Twenty cases (87%) showed high X-ray absorption in the stomach, while the other three did not demonstrate radio-dense stomach contents even though drug analysis detected lethal concentrations of drugs in the blood. In conclusion, drugs were frequently, but not always, visualized as contents with high X-ray absorption in the stomach. Postmortem gastric CT images can provide useful information in cases of oral drug intoxication if there are empty drug packages or a suicide note at the death scene. However, precise determination of the cause of death requires full autopsy in cases where there is no indication of suicide at the death scene.

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

OBJECTIVE: To evaluate the difference in sinus fluid volume and density between saltwater and freshwater drowning and diagnose saltwater drowning in distinction from freshwater drowning. METHODS: Ninety-three drowning cases (22 saltwater and 71 freshwater) were retrospectively investigated; all had undergone post-mortem CT and forensic autopsy. Sinus fluid volume and density were calculated using a 3D-DICOM workstation, and differences were evaluated. Diagnostic performance of these indicators for saltwater drowning was evaluated using a cut-off value calculated by receiver operating characteristic (ROC) analysis. RESULTS: The median sinus fluid volume was 5.68 mL in cases of saltwater drowning (range 0.08 to 37.55) and 5.46 mL in cases of freshwater drowning (0.02 to 27.68), and the average densities were 47.28 (14.26 to 75.98) HU and 32.56 (-14.38 to 77.43) HU, respectively. While sinus volume did not differ significantly (p = 0.6000), sinus density was significantly higher in saltwater than freshwater drowning cases (p = 0.0002). ROC analysis for diagnosis of saltwater drowning determined the cut-off value as 37.77 HU, with a sensitivity of 77 %, specificity of 72 %, PPV of 46 % and NPV of 91 %. CONCLUSION: The average density of sinus fluid in cases of saltwater drowning was significantly higher than in freshwater drowning cases; there was no significant difference in the sinus fluid volume. KEY POINTS: • Sinus fluid density of saltwater drowning is significantly higher than freshwater drowning. • Cut-off value was 37.77 HU based on the ROC analysis. • The cut-off value translated to 91 % NPV for diagnosis of saltwater drowning.

A Case Report of Postmortem Radiography of Acute, Fatal Abdominal Distension After Binge Eating.

This case report describes a woman who developed fatal gastric dilatation after binge eating. She called an ambulance because of stomach pain. When she arrived at the hospital, she did not look seriously ill. However, she rapidly became unconscious and collapsed immediately after she was laid on the examination table in a supine position. Postmortem chest x-ray and computed tomography showed right shift of the mediastinum and raised left diaphragm caused by massive gastric distension. Computed tomography showed no visible inferior vena cava. We think that her sudden deterioration was caused by movement of her stomach contents. Radiographic images provided some clues to the cause of her rapid collapse and death.

An Autopsy Case of a Pregnant Woman With Severe Placental and Fetal Damage From Domestic Violence.

We present an autopsy case of a pregnant woman who was a victim of domestic violence. The deceased showed injuries mainly to her head and abdomen. Postmortem examination revealed 1400 mL of abdominal hemorrhage, ablation of the perimetrium, placental avulsion, and intracranial hematoma. The cause of death was diagnosed as hemorrhagic shock. The uterus contained a fetus of 7 months' gestational age. Fetal autopsy revealed laceration of the lungs, laceration and avulsion of the liver, and 15 mL of hemoperitoneum. Both placental and fetal injuries suggested repeated severe attacks to the abdomen, such as those expected to result from kicking or hitting.

A case report of forensic personal identification by transposed teeth and dental treatment marks using multidetector row computed tomography.

Using postmortem computed tomography (CT) images, we achieved personal identification of a body using transposed teeth and dental treatment marks. Transposition of teeth is a rare malpositioning anomaly. CT images can clarify the malpositioning of the teeth's roots, which is difficult to discern from gross observation of the dentition. Because dental hygiene has reduced the incidence of caries in recent years, it might be difficult to use treatment marks for personal identification in the future. Transposed teeth, although rare, provide an important clue to personal identification.

Inconsistency between Human Observation and Deep Learning Models: Assessing Validity of Postmortem Computed Tomography Diagnosis of Drowning.

Drowning diagnosis is a complicated process in the autopsy, even with the assistance of autopsy imaging and the on-site information from where the body was found. Previous studies have developed well-performed deep learning (DL) models for drowning diagnosis. However, the validity of the DL models was not assessed, raising doubts about whether the learned features accurately represented the medical findings observed by human experts. In this paper, we assessed the medical validity of DL models that had achieved high classification performance for drowning diagnosis. This retrospective study included autopsy cases aged 8-91 years who underwent postmortem computed tomography between 2012 and 2021 (153 drowning and 160 non-drowning cases). We first trained three deep learning models from a previous work and generated saliency maps that highlight important features in the input. To assess the validity of models, pixel-level annotations were created by four radiological technologists and further quantitatively compared with the saliency maps. All the three models demonstrated high classification performance with areas under the receiver operating characteristic curves of 0.94, 0.97, and 0.98, respectively. On the other hand, the assessment results revealed unexpected inconsistency between annotations and models' saliency maps. In fact, each model had, respectively, around 30%, 40%, and 80% of irrelevant areas in the saliency maps, suggesting the predictions of the DL models might be unreliable. The result alerts us in the careful assessment of DL tools, even those with high classification performance.

[Role of forensic autopsy in deaths caused by medical practice].

Autopsies are required to determine the cause of deaths due to medical practice. In Japan, some deaths resulting from medical practice are treated as criminal cases. In such instances, medicolegal autopsies ordered by the police or public prosecutors are performed. One problem with a medicolegal autopsy, however, is that judicial institutes often refuse to disclose coroners' reports. As a result, parties with an interest in the findings (the bereaved or medical institutions) are unable to receive detailed autopsy information for a long period of time. When an autopsy is performed by a medical examiner who is a government official, the rules governing the disclosure of the coroner's report may not be as strict, at least for the bereaved, although such a system is in place in only four regions of Japan. In April 2013, a new law pertaining to the cause of death will come into effect. However, it does not include new articles relating to deaths caused by medical practice, meaning that such deaths will continue to be investigated under existing regulations in the present law, which includes the Medical Practitioners' Act. The government plans to draft another law covering deaths related to medical practice, and it is hoped that clinical medical societies, including the Japan Surgical Society, will appeal to the government to solve problems related to the determination of the cause of deaths related to medical practice.

A 2.5D Deep Learning-Based Method for Drowning Diagnosis Using Post-Mortem Computed Tomography.

It is challenging to diagnose drowning in autopsy even with the help of post-mortem multi-slice computed tomography (MSCT) due to the complex pathophysiology and the shortage of forensic specialists equipped with radiology knowledge. Therefore, a computer-aided diagnosis (CAD) system was developed to help with diagnosis. Most deep learning-based CAD systems only utilize 2D information, which is proper for 2D data such as chest X-ray images. However, 3D information should also be considered for 3D data like CT. Conventional 3D methods require a huge amount of data and computational cost when using 3D methods. In this article, we proposed a 2.5D method that converts 3D data into 2D images to train 2D deep learning models for drowning diagnosis. The key point of this 2.5D method is that it uses a subset to represent the whole case, covering this case as much as possible while avoiding other repetitive information. To evaluate the effectiveness of the proposed method, conventional 2D, previous 2.5D, and 3D deep learning-based methods were tested using an MSCT dataset obtained from Tohoku university. Then, to provide explainable diagnosis results, a visualization method called Gradient-weighted Class Activation Mapping was employed to visualize features relevant to drowning in CT images. Results on drowning diagnosis showed that our proposed method achieved the best performance compared to other 2D, 2.5D, and 3D methods. The visual assessment also demonstrated that our method could find the saliency regions corresponding to drowning.

Detection of major psychoactive compounds (safrole, myristicin, and elemicin) of nutmeg in human serum via GC-MS/MS using MonoSpin® extraction: Application in a nutmeg poisoning case.

Nutmeg is an inexpensive, readily available spice used in a variety of recipes. However, the use of nutmeg powder as a recreational drug for its hallucinogenic effects is resulting in an increase in overdose rates. We encountered a male patient being hospitalized after ingesting 75 g of commercially available nutmeg powder with the intent of committing suicide. There are no available reports documenting the toxic or comatose-fatal blood concentrations or time-course of drug action in cases of nutmeg poisoning. Therefore, to improve patient management, we endeavored to determine the blood serum levels and time-course of the major psychoactive compounds (safrole, myristicin, and elemicin) present in nutmeg. We designed a simple and reliable method using the MonoSpin® extraction kit and gas chromatography-tandem mass spectrometry to detect the presence of these psychoactive compounds in human serum. The method had detection and quantitation limits of 0.14-0.16 and 0.5 ng/mL (lowest calibration points), respectively. The calibration curves displayed excellent linearity (0.996-0.997) for all three compounds at 0.5-300 ng/mL blood concentrations. The intra- and inter-day precision values for quality assurance were in the ranges of 2.4-11 % and 2.5-11 %, respectively; bias ranged from - 2.6 % to 2.1 %. Blood serum levels of safrole, myristicin, and elemicin were measured at admission (approximately 8 h post-ingestion) and approximately 94 h after a post-admission fluid therapy to evaluate their biological half-lives. We developed this method to obtain information on the psychoactive constituents of nutmeg and, thereby, determine the toxicokinetic parameters of nutmeg in a case of nutmeg poisoning.

Cervical intervertebral separation caused by trauma on post-mortem computed tomography: Possibility of a diagnosis based on intervertebral gas.

OBJECTIVES: Gas is a common finding in cervical intervertebral separation. However, intervertebral gas is also found in many decedents without intervertebral separation. Here, we quantified intervertebral gas and examined its value in the diagnosis of cervical intervertebral separation. METHODS: We retrospectively reviewed data from 1118 decedents who underwent post-mortem computed tomography (CT) and autopsy from May 2011 to July 2016 and selected those with cervical intervertebral gas with or without intervertebral separation. These data comprised 56 cervical intervertebral spaces with gas [intervertebral separation in 19 (33.9%)] in 43 subjects [intervertebral separation in 17 (39.5%)]. We categorised the decedents according to gas volume, position, and shape and determined the significance of the differences between the decedents with and without separation. RESULTS: The gas volume did not differ significantly between decedents with and without separation (p = 0.063). However, there were significant differences in the gas position between decedents with and without separation. In the sagittal plane: gas was seen in the "centred" position in the ventral-to-dorsal direction in more decedents without separation than in those with separation (p = 0.018). Gas was seen in the ventral-to-dorsal positions in more decedents with separation than in those without separation (p = 0.049). In the cranio-caudal direction, gas in the upper position was more common in decedents with separation than in those without separation in the sagittal plane (p = 0.03). In the coronal plane: gas was seen in the upper position more frequently in decedents with separation in the cranio-caudal direction than in those without separation (p = 0.001). A significant difference in gas shape was observed only in the coronal plane (p = 0.024); irregular gas was associated with decedents without separation. CONCLUSION: Gas in the ventral-to-dorsal and upper positions in the sagittal plane and in the upper position in the coronal plane was rather indicative of cervical intervertebral separation. An irregular gas shape in the coronal plane was indicative of degenerative changes.

Allele frequencies of 31 autosomal short tandem repeat (auSTR) loci obtained using the Precision ID GlobalFiler™ NGS STR Panel v2 in 322 individuals from the Japanese population.

In human identification methods that target short tandem repeats (STRs), massively parallel sequencing (MPS) technology has made it possible to genotype at the level of the specific sequence itself. This allows for the detection of repeat unit variants and single nucleotide polymorphisms (SNPs) adjacent to the STRs. Using the GlobalFiler™ NGS STR Panel v2, Ion S5, and Converge software, this study constructed a Japanese database of 31 autosomal STRs (auSTRs) and two sex markers from 322 individuals. After excluding some sequence errors and stutters, a total of 31 novel alleles were identified. Additionally, using the allele frequencies of 31 auSTR loci, the match probabilities for the length-based and sequence-based data were calculated to be 1.433 × 10-34 and 9.163 × 10-38, respectively. These values are at least nine orders of magnitude higher than that obtained from 21 auSTR loci in the Japanese population using the conventional capillary electrophoresis method. The database generated in this study is expected to be implemented in forensic practice and used to solve difficult casework.

Usefulness of catheter guide wires for identifying sites of vascular injuries.

We report 2 cases in which catheter guide wires were useful for detection of vascular injury site. Case 1: A woman was died of hemorrhagic shock after being slashed at the extremities, but the vessels were so collapsed that it was not easy to find the injured site. After a wound track on the left forearm was cut open and a guide wire was inserted, the injury site was detected expeditiously at the left radial artery. Case 2: A woman was stabbed and died of hemorrhagic shock. An autopsy revealed 2 stab wounds in the back, one of which made a cut in the left lung. The wound track was cut open, and the injured vessel was revealed. It was too small in diameter to macroscopically determine whether the injured branch arose from, and so a guide wire was introduced from the injured site, and the injured vessel was easily determined to be a branch of the left pulmonary artery. Guide wires have many features, such as elasticity, flexibility, and hydrophilicity, which are considered to be applicable to forensic uses. The guide wire technique is easy, less invasive, highly vasoselective, and reproducible in identifying vascular injury sites.

LC-MS/MS method for rapid and accurate detection of caffeine in a suspected overdose case.

Excessive intake of caffeine, otherwise known to be a safe and mild central nervous system stimulant, causes nausea, vomiting, convulsions, tachycardia, and eventually fatal arrhythmias and death. Caffeine intoxication, a global problem, has been increasing in Japan since 2013. Thus, there is a need for rapid and accurate diagnosis of caffeine poisoning in forensic and clinical toxicology investigations. Herein, we demonstrate rapid and accurate caffeine quantitation by liquid chromatography tandem mass spectrometry using the standard addition method in a fatal case. Biological samples were diluted 500-100,000-fold and subjected to a simple pretreatment (adding caffeine standard and internal standard and passing through a lipid removal cartridge). The multiple reaction monitoring transitions were 195 â†’ 138 for quantitation, 195 â†’ 110 for the qualifier ion, and 204 â†’ 144 for the internal standard (caffeine-d9). The standard plots were linear over 0-900 ng/mL (r2 = 0.9994-0.9999) for biological samples, and the reproducibility (%RSD) of the method was 1.53-6.97% (intraday) and 1.59-10.4% (interday). Fatal levels of caffeine (332 µg/mL) and toxic to fatal levels of olanzapine (625 ng/mL), along with other pharmaceuticals were detected in the external iliac venous blood. The cause of death was determined to be multi-drug poisoning, predominantly caused by caffeine. Our method is useful for not only forensic cases but also the rapid diagnosis of caffeine overdose in emergency clinical settings.

A Deep Learning Aided Drowning Diagnosis for Forensic Investigations using Post-Mortem Lung CT Images.

Feasibility of computer-aided diagnosis (CAD) systems has been demonstrated in the field of medical image diagnosis. Especially, deep learning based CAD systems showed high performance thanks to its capability of image recognition. However, there is no CAD system developed for post-mortem imaging diagnosis and thus it is still unclear if the CAD system is effective for this purpose. Particulally, the drowning diagnosis is one of the most difficult tasks in the field of forensic medicine because findings of the post-mortem image diagnosis are not specific. To address this issue, we develop a CAD system consisting of a deep convolution neural network (DCNN) to classify post-mortem lung computed tomography (CT) images into two categories of drowning and non-drowning cases. The DCNN was trained by means of transfer learning and performance evaluation was conducted by 10-fold cross validation using 140 drowning cases and 140 non-drowning cases of the CT images. The area under the receiver operating characteristic curve (AUC-ROC) for the DCNN was achieved 0.88 in average. This high performance clearly demonstrated that the proposed DCNN based CAD system has a potential for post-mortem image diagnosis of drowning.

A fast paraquat quantitation method in human serum using probe electrospray ionization-tandem mass spectrometry for emergency settings.

INTRODUCTION: Paraquat (PQ) is one of the most toxic herbicides to humans. However, it is still in use in many countries, including Japan, and many incidents, such as homicides, intentional ingestions, and occupational accidents, have been reported thus far. In PQ poisoning cases, it is possible to predict severity and prognosis using nomograms. Therefore, if the serum PQ level is determined immediately, a treatment plan can be rapidly established. However, most known analytical methods are time-consuming and therefore hardly ever contribute to patient treatment. METHODS: We developed a new method for PQ quantitation in serum by combining a probe electrospray ionization technique with mass spectrometry. This method requires virtually no serum pretreatment and can yield quantitation values in 18 s. RESULTS: We applied the proposed method to samples from real poisoning cases and compared the results with those obtained via liquid-chromatography-tandem mass spectrometry, revealing the absence of any significant differences at the 5% significance level (t(8) = 1.000, p > .05). The limits of detection and quantitation were 0.004 and 0.015 µg/L, respectively, and the calibration curve exhibited good linearity over the concentration range of 0.015-4.0 µg/mL (r2 = 0.998). DISCUSSION: As the proposed method is fast and easy to perform, it should be useful in emergency medical settings.