Parameterized Analysis of Craniocerebral Injury Caused by Fist / 法医学杂志

Objective Based on the theory of biomechanics, the finite element method was used to study the injury characteristics of different parts of brain hit by fist with different force and to predict the risk of craniocerebral injury, in order to provide reference for actual medical protection and forensic identification. Methods The finite element model of fist was constructed by using DICOM data modeling method and related software, and the effective mass and speed of fist were used to represent the kinetic energy of fist, and combined with human finite element model THUMS 4.02, the characteristics of craniocerebral injury caused by frontal and lateral blows were parametrically simulated. Results The probability of direct death from a blow to the head was low, but as fist power increased, so did the risk of craniocerebral injury. The characteristics of craniocerebral injury were also significantly different with the different fist hitting head locations. When the frontal area was attacked, the maximum equivalent stress of skull was 122.40 MPa, while that of brain tissue was 4.31 kPa. When the temporal area was attacked, the maximum equivalent stress of skull was 71.53 MPa, while that of brain tissue was 7.09 kPa. Conclusion The characteristics and risks of skull fracture and brain tissue injury are different when different parts of the brain are hit by fist. When the frontal area is hit, the risk of skull fracture is significantly higher than when the temporal area is hit. The risk of brain tissue injury is the opposite. The position with the highest probability of skull fracture is generally the place where the skull is directly impacted, and with the conduction of stress waves, it will spread to other parts of the skull, while the position with the highest risk of brain tissue injury is not the place where the brain is directly impacted.

Application of Artificial Intelligence Automatic Diatom Identification System in Practical Cases / 法医学杂志

Objective To discuss the application of artificial intelligence automatic diatom identification system in practical cases, to provide reference for quantitative diatom analysis using the system and to validate the deep learning model incorporated into the system. Methods Organs from 10 corpses in water were collected and digested with diatom nitric acid; then the smears were digitally scanned using a digital slide scanner and the diatoms were tested qualitatively and quantitatively by artificial intelligence automatic diatom identification system. Results The area under the curve （AUC） of the receiver operator characteristic （ROC） curve of the deep learning model incorporated into the artificial intelligence automatic diatom identification system, reached 98.22% and the precision of diatom identification reached 92.45%. Conclusion The artificial intelligence automatic diatom identification system is able to automatically identify diatoms, and can be used as an auxiliary tool in diatom testing in practical cases, to provide reference to drowning diagnosis.

Evaluation of 3D Measuring Methods for Body Surface Damage and Scars / 法医学杂志

Objective To assess the accuracy and reliability of the two 3D measuring methods, structured-light scanning and single-camera photogrammetry in forensic body surface damage and scar measurement. Methods The measuring results of 86 injuries by the ruler method, structured-light scanning and single-camera photogrammetry were compared and evaluated. The area measuring results of 13 simulated scars by the structured-light scanning, single-camera photogrammetry, Photoshop lasso pixel method and PDF reading software were compared and evaluated. The time consumed was recorded. The known specification information of the stickers was used as the standard value to compare the measuring accuracy of the ruler method, structural-light scanning and single-camera photogrammetry, and to calculate the root mean square error （RMSE）. The consistency evaluation of intraclass correlation coefficient （ICC） for the repeatability of 3 measuring results obtained by different operators and the same operator. Results The differences in results of the two 3D measuring methods and the ruler method had no statistical significance; the differences between measuring results made by the structured-light scanning, single-camera photogrammetry and PDF reading software and that of the Photoshop lasso pixel method had no statistical significance. The post-processing of the single-camera photogrammetry consumed more time than that of other methods. When the long-distance group （10-40 cm） was measured, the results obtained by the ruler method were shorter than the standard value. The RMSE value results were structured-light scanning < single-camera photogrammetry < ruler method. The ICC value intragroup and intergroup were greater than 0.99. Conclusion Both structured-light scanning and single-camera photogrammetry can be applied in recording and measuring forensic body surface damage. The former has better performance in measurement accuracy and stability, while the latter has better color performance but longer post-processing time.

Exploring of the Mechanism of Rib Fracture Caused by Landing on Different Parts of the Trunk after Falls from Height Using Finite Element Method / 法医学杂志

Objective To study the mechanism of rib fracture caused by landing on different parts of the trunk using finite element method, and to provide some new techniques and new ideas for the reconstruction of the whole process of falls from height. Methods The finite element method was used to study the rib fracture of human security model THUMS4.0 caused by landing on different parts of the trunk. Then the model was compared with actual cases and the mechanism of rib fracture caused by falls from height was analyzed from a biomechanical point of view. Results There were some differences in the stress and strain distribution as well as the rib fracture sites when different parts touched the ground. Ribs on both sides of the body were fractured when the front of the trunk touched the ground, and the fractures were mainly located in the junction of the ribs and costal cartilage and the midaxillary line area. When the right anterior part of the trunk touched the ground, rib fracture occurred first on the side that touched the ground, and rib fractures were mainly located in the area from the right midaxillary line to the posterior axillary line, and junction of ribs on both sides and costal cartilage. When the back of the trunk touched the ground, the fracture sites were mainly located on the back of the ribs on both sides. When the right posterior part of the trunk touched the ground, multiple rib fractures were likely to occur in the parts that touched the ground. The plastic strains were mainly concentrated at the fracture sites, while the von Mises stresses were not only concentrated at the fracture sites, but also at other sites. Conclusion There are some differences in rib fracture location sites and injury mechanisms when different parts of the trunk touch the ground.

Research Status of Postmortem MSCT Angiography in Forensic Science / 法医学杂志

Virtual autopsy is a new technique for investigating the morphological changes of cadaveric tissues and organs by medical imaging technology. It has been widely used in the identification of causes of death. Multislice spiral computed tomography （MSCT） has become a routine inspection method in some identification institutions, although it cannot completely replace traditional autopsy, it plays a key auxiliary or substitute role in the identification of certain abnormal causes of death. Plain MSCT scan cannot visualize cadaveric vessels, but can perform cadaveric angiography to determine vascular injury or disease. This technology has entered a rapid development period in recent years, and has made a considerable progress in contrast agent, perfusion methods and imaging methods. This article summarizes several common cadaveric MSCT angiography methods, such as systemic angiography, angiography through cardiopulmonary resuscitation, targeted angiography, and angiography by cardiac puncture, and analyzes and compares the application prospects.

Research Progress on Estimation of Postmortem Interval Using mRNA and ncRNA / 法医学杂志

Postmortem interval （PMI） estimation has always been an important and difficult issue in the field of forensic pathology. In recent years, research progress on the estimation of PMI using RNA specific variation patterns after death has been made by researchers at home and aboard. This paper summarizes the specific application methods of messenger RNA and non-coding RNA for PMI estimation based on the literatures and discusses the existing problems and development trends, in order to provide technical reference for related studies and estimation practice.

Analysis of Influencing Factors of Single Camera Photogrammetry in Forensic Three-Dimensional Reconstruction / 法医学杂志

Objective To evaluate the influence of factors such as the selection of equipment, focal length and the selection of reconstruction quality in the reconstruction software on the reconstruction results of single camera photogrammetry and provide reference for the forensic application of single camera photogrammetry. Methods The 19 skulls were measured by traditional measurement method and single camera photogrammetry. The differences between the two measurement methods and within the group with same equipment but different focal length were analyzed. One skull and one corpse were selected as the research objects. According to the reconstruction quality selection conditions in the photogrammetric software, the experimental group was divided into five grades. The model reconstructed by optical scanner was defined as reference model, while the model reconstructed by single camera photogrammetry was defined as test model. The test model was aligned with the reference model, 3D deviation analysis was carried out and the mean error and root mean square （RMS） values were calculated. Results The differences between EOS 7D zoom group and traditional measurement, and within the group with same equipment had statistical significance （P<0.05）. The mean error value and minimum RMS value of the skull reconstructed by single camera photogrammetry and the three-dimensional model of the corpse existed in the medium quality group, and the trend was basically the same. Conclusion The equipment and focal length has no obvious influence on the results of single camera photogrammetry. Lower reconstruction quality can easily cause distortion, while higher reconstruction quality can easily generate noise, so medium quality is preferred.

Research Progress on Postmortem Changes of Computed Tomography Imaging Characteristics on Corpses / 法医学杂志

Postmortem changes on corpses appear immediately after death, and can transform the original structure characteristics of the corpse to different degrees as well as show specific changes on computed tomography （CT） images, sometimes with false positives and false negatives, influencing the identification of injuries or diseases. This paper systematically summarizes the postmortem changes of computed tomography imaging characteristics on corpses, to further expand the application of virtopsy in the practices of forensic pathology identification, and provide reference for the identification of injuries, diseases and changes after normal death.

Quantitative Expression of RNA from Frozen Organs and Formaldehyde-fixed and Paraffin-embedded Tissues / 法医学杂志

Objective Quantitative analysis and comparison of the expression of ribonucleic acid （RNA） from frozen organs and formaldehyde-fixed and paraffin-embedded （FFPE） tissues. Methods Frozen specimens of human brain, myocardium and liver tissues as well as FFPE samples at different postmortem intervals were collected and mass concentration of RNA was extracted and detected. Reverse transcription-quantitative polymerase chain reaction （RT-qPCR） technology was used to analyze the amplification efficiency and relative expression of each RNA marker. Results The mass concentration and integrity of RNA extracted from FFPE samples were relatively low compared with frozen specimens. The amplification efficiency of RNA markers was related with RNA species and the length of amplification products. Among them, glyceraldehyde-3-phosphate dehydrogenase （GAPDH） and β-actin （ACTB） with relatively long amplification products failed to achieve optimal amplification efficiency, whereas 5S ribosomal RNA （5S rRNA） achieved ideal amplification efficiency and showed quite stable expression across various tissues, therefore it was chosen as internal reference marker. The expression quantity of GAPDH and ACTB in frozen specimens with longer postmortem intervals and in FFPE samples with relatively long amplification products was decreased. The expressions of tissue-specific microRNAs （miRNAs）, GAPDH and ACTB with relatively short amplification products had consistency in the same tissues and FFPE samples. Conclusion Through standardizing the RT-qPCR experiment, selecting the appropriate RNA marker and designing primers of appropriate product length, RNA expression levels of FFPE samples can be accurately quantified.

Research Progress in Virtopsy of Drowning / 法医学杂志

Dead bodies found in the water are not all caused by drowning. The important task of forensic identification is to distinguish between entering the water before and after death, and to clarify the cause of death. In the practice of forensic identification, drowning is generally diagnosed on the basis of comprehensive considerations such as cadaveric signs, histopathological examinations, and diatom tests, with the exclusion of other causes of death. The emergence of virtopsy techniques provides new insights for the diagnosis of drowning. This paper reviews the post-mortem imaging studies of sinus and mastoid small chambers, respiratory tracts, lung tissues, gastrointestinal tracts and blood in the corpses in recent years. The value, potential of virtopsy in the diagnosis of drowning is discussed, with the prospects of its development direction.

Characteristic Changes and 3D Virtual Measurement of Lung CT Image Parameters in the Drowning Rabbit Model / 法医学杂志

OBJECTIVES@#To use virtual anatomy technique in the analysis of post-mortem characteristic changes of CT images in the experimental drowning rabbit model and the related parameters in 3D virtual model, so as to explore its application value in the diagnosis of drowning in forensic pathology.@*METHODS@#A model of drowning rabbits was established, with animal models of hemorrhagic shock and mechanical asphyxia as the controls. CT scan was performed on the experimental animals, and the differences in imaging features between the groups were compared by morphological reading of the tomographic images. CT data were imported into Mimics 14.0 software for 3D modeling. The CT values and lung volumes were calculated by the software, and the differences on CT values and lung volumes brought by different causes of death were analyzed.@*RESULTS@#The CT images of lungs in the drowning group showed characteristic ground-glass opacity （diffuse and uniform density increase）. There were no obvious abnormalities in hemorrhagic shock group, and only a few similar changes were found in the mechanical asphyxia group. Compared with the controls, the CT values and the lung volumes in the drowning group were significantly increased P<0.05.@*CONCLUSIONS@#Based on post-mortem lung imaging, the combination of CT value and lung volume changes can effectively reflect the virtual anatomical features in drowning, and provide a diagnostic basis for the forensic identification of drowning.

Methodological research of RNA extraction and quantitative analysis of long non-coding RNA from formalin-fixed paraffin-embedded human brain specimens / 上海交通大学学报（医学版）

Objective·To compare the quality of RNA extracted from fresh and formalin-fixed paraffin-embedded (FFPE) brain tissues and to explore the long non-coding RNA (IncRNA) expression level.Methods·FFPE samples stored under various conditions and paired frozen brain tissues were collected and total RNA qualities were then detected.Amplification efficiency (AE) and expression stability of each RNA marker were calculated and analyzed based on real-time quantitative PCR.After selecting reference biomarkers,normalized △ Ct values of candidate makers within different amplicon size were measured to assess the possibility of lncRNA quantification in FFPE tissues.Results·The purity of RNA extracted from FFPE was relatively high,but the RNA integrity was lower than fresh samples.All biomarkers were successfully amplified and amplification efficiencies of long-chain RNA markers were correlated with amplicon sizes,sample treatment and preservation conditions,namely temperature and storage time.5S,miR-9 and miR 125b achieved optimal AE and showed quite stable expression in all specimens,therefore they were chosen as control markers.Compared with fresh samples,the △ Ct values of only 2 lncRNA (HAR1F and MALAT1-L,whose amplicon size were both higher than 200 bp,respectively) increased in the FFPE samples kept in 4 ℃,while in FFPE tissues kept in room temperature,increments of the △ Ct values were significant for most target genes except for short amplicon markers (＜60 bp),which showed consistently stable expression in all brain specimens.Conclusion·RNA integrity is affected by sample treatment and preservation conditions,but IncRNA expression levels in FFPE tissues can be accurately quantificated by using optimal amplicon sizes and considerable reference markers.

Diagnostic Value of Postmortem CT Angiography in Coronary Atherosclerosis / 法医学杂志

OBJECTIVES@#To explore the application value of postmortem computed tomography （CT） angiography on diagnosis of coronary atherosclerotic stenosis degree.@*METHODS@#Based on the previous experimental results, the postmortem CT angiography device of human isolated heart was improved. Different coronary atherosclerotic stenosis degree of sudden death cases was selected. Before the cardiac anatomy, hearts were removed out completely and CT angiography was performed immediately. The CT angiography results were compared with histopathological findings. Meanwhile, the advantages and disadvantages of the angiography device before and after improvement were compared.@*RESULTS@#The improved angiography device of isolated heart could get better imaging results. The postmortem CT angiography results had high consistency with the histopathological findings on diagnosis of coronary atherosclerotic stenosis degree. And the coronary artery lesions could be revealed more objectively and vividly by 3D reconstruction technology. However, CT angiography could only be used to examine the pathological changes of blood vessels, which might have some limitations on the diagnosis of cause of death.@*CONCLUSIONS@#Postmortem CT angiography can be used as an additional method for the conventional autopsy in the cases of coronary atherosclerosis.

Reconstruction of Vehicle-human Crash Accident and Injury Analysis Based on 3D Laser Scanning, Multi-rigid-body Reconstruction and Optimized Genetic Algorithm / 法医学杂志

Objective To reconstruct a vehicle-bicycle-cyclist crash accident and analyse the injuries us-ing 3D laser scanning technology, multi-rigid-body dynamics and optimized genetic algorithm, and to provide biomechanical basis for the forensic identification of death cause. Methods The vehicle was measured by 3D laser scanning technology. The multi-rigid-body models of cyclist, bicycle and vehicle were developed based on the measurements. The value range of optimal variables was set. A multi-ob-jective genetic algorithm and the nondominated sorting genetic algorithm were used to find the optimal solutions, which were compared to the record of the surveillance video around the accident scene. Re-sults The reconstruction result of laser scanning on vehicle was satisfactory. In the optimal solutions found by optimization method of genetic algorithm, the dynamical behaviours of dummy, bicycle and ve-hicle corresponded to that recorded by the surveillance video. The injury parameters of dummy were consistent with the situation and position of the real injuries on the cyclist in accident. Conclusion The motion status before accident, damage process by crash and mechanical analysis on the injury of the victim can be reconstructed using 3D laser scanning technology, multi-rigid-body dynamics and opti-mized genetic algorithm, which have application value in the identification of injury manner and analysis of death cause in traffic accidents.

New Progress of MALDI-TOF-IMS in the Study of Proteomics / 法医学杂志

Matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI-TOF-IMS) has been a classical technique for studying proteomics in present and a tool for analyzing the distribution of proteins and small molecules within biological tissue sections. MALDI-TOF-IMS can analyze multiple unknown compounds in biological tissue sections simultaneously through a single measurement which can obtain molecule imaging of the tissue while maintaining the integrity of cellular and molecules in tissue. In recent years, imaging mass spectrometry technique develops relatively quickly in all biomedical domain. This paper based on the relevant data and reviews the present developing level of MALDI-TOF-IMS, the principle of imaging mass spectrometry, methology and the prospect in forensic pathology.

Comparison of Postmortem MSCT and Autopsy Findings in Traffic Accident Victims / 法医学杂志

OBJECTIVE@#To explore the application value of postmortem multi-slice spiral computed tomography (MSCT) by observing and analyzing the injury features in the traffic accident victims.@*METHODS@#Ten traffic accident victims were scanned with whole body MSCT. The systemic autopsy was subsequently performed to compare with the results of MSCT. The advantages and disadvantages of autopsy and MSCT for obtaining the information of traffic accident injuries were then analyzed.@*RESULTS@#MSCT could reveal 3D shape of fractures clearly and detect air accumulation in different positions of the body, which showed the obvious advantages compared with autopsy. However, the resolution of MSCT was limited compared to the detection of organ and soft tissue injuries.@*CONCLUSION@#A combination of MSCT and autopsy is the best way for determining the manner and the cause of death in traffic fatality victims.

Determination of a Newborn with Lethal Type II Osteogenesis Imperfecta and Other Anomalies Using Autopsy and Postmortem MSCT--A Case Report / 法医学杂志

A case of a stillbirth with lethal type II osteogenesis imperfecta (OI) was reported. The fetus had skull fractures and craniocerebral injuries during pregnancy. Postmortem multi-sliced computed tomography (MSCT) and 3D-reconstruction were performed, followed by a medico-legal autopsy. The autopsic findings showed the typical features of type II OI, including a soft calvarium, deformed extremities, flexed and abducted hips, and uncommon features, such as white sclera, coxa vara, absence of several bones and organs, a cleft lip, and asymmetric ears. The radiologic images revealed such anomalies and variations as a cleft palate, mandibular dysplasia, spina bifida, costa cervicalis, and fusion of the ribs and vertebrae, which were difficult to detect during conventional autopsy. The paper investigated the classification, causative mutation, cause of death, and the differentiation of OI from child abuse, coming to a conclusion that OI knowledge can be of great importance to forensic pathologists and that the merits of postmortem MSCT should be emphasized in forensic pathologic examinations.

Proteomic Analysis of Rat Brain Stem with DAI by MALDI-TOF-MS / 法医学杂志

OBJECTIVE@#To establish a diagnostic model for diffuse axonal injury (DAI) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). To screen the proteins or peptides associated with DAI for providing the biomarkers with theoretic foundation.@*METHODS@#Fifteen male Sprague-Dawley rats were randomly divided into DAI group (n = 10) and control group (n = 5). The protein or peptide expression profiles of rat brain stem were detected by MALDI-TOF-MS. ClinProTools 2.2 software was used to find specific peaks, and a diagnostic model was established by the genetic algorithm.@*RESULTS@#There were significant differences in 61 peaks of DAI group (P < 0.05), 9 peaks were down-regulated and 52 up-regulated. The diagnostic model was established based on 5 different peaks. The specificity and sensitivity of cross validation was 96.14% and 95.98%; while the specificity and sensitivity of blind validation showed was 73.33% and 70.00%, respectively.@*CONCLUSION@#A specific and sensitive diagnostic model of DAI can be established by MALDI-TOF-MS to provide a potential value for determining DAI in forensic practice.

Research Progress on Biomechanics of Craniocerebral Injury in Children / 法医学杂志

In the researches of biomechanics for child craniocerebral injury, the research progress of performance parameter detection for brain, skull, cranial suture and dura mater, and the finite element model construction for child's head were reviewed. Meanwhile, the shortcomings of the established finite element model construction of child's head were analyzed. Thus, it is necessary to strengthen the material properties parameter detection of child's head, and establish the relevant database, so as to lay the foundation for establishing an accurate finite element model of child's head.

Analysis of Differentially Expressed Proteins Distribution in the Rat Brains with DAI by MALDI-TOF-IMS / 法医学杂志

OBJECTIVES@#To establish the imaging mass spectrometry for analysis of differentially expressed proteins distribution in the rat brains with diffuse axonal injury （DAI） based on matrix assisted laser desorption/ionization-time of flight imaging mass spectrometry （MALDI-TOF-IMS）.@*METHODS@#MALDI-TOF-IMS scanning were conducted on the brains of DAI group and control group in the m/z range of 1 000 to 20 000 using AutoflexⅢ MALDI-TOF spectrometer. ClinProTool 2.2 software was used for statistical analysis on the data of two groups, and then the differentially expressed proteins were picked out to conduct imaging. The distribution of the proteins with different m/z in the rat brains was observed.@*RESULTS@#Five proteins with different m/z, including 4 963, 5 634, 6 253, 6 714 and 7 532, differentially expressed in the rat brains with DAI.@*CONCLUSIONS@#MALDI-TOF-IMS can be used for studying the differentially expressed proteins in rat brains with DAI and the analysis method is established for exploring the distribution of differentially expressed proteins in the rat brains with DAI using imaging mass spectrometry.