Application of Medical Statistical and Machine Learning Methods in the Age Estimation of Living Individuals.

In the study of age estimation in living individuals, a lot of data needs to be analyzed by mathematical statistics, and reasonable medical statistical methods play an important role in data design and analysis. The selection of accurate and appropriate statistical methods is one of the key factors affecting the quality of research results. This paper reviews the principles and applicable principles of the commonly used medical statistical methods such as descriptive statistics, difference analysis, consistency test and multivariate statistical analysis, as well as machine learning methods such as shallow learning and deep learning in the age estimation research of living individuals, and summarizes the relevance and application prospects between medical statistical methods and machine learning methods. This paper aims to provide technical guidance for the age estimation research of living individuals to obtain more scientific and accurate results.

Comparison of CT Values between Thrombus and Postmortem Clot Based on Cadaveric Pulmonary Angiography.

OBJECTIVES: To explore the difference in CT values between pulmonary thromboembolism and postmortem clot in postmortem CT pulmonary angiography (CTPA) to further improve the application value of virtual autopsy. METHODS: Postmortem CTPA data with the definite cause of death from 2016 to 2019 were collected and divided into pulmonary thromboembolism group (n=4), postmortem clot group (n=5), and control group (n=5). CT values of pulmonary trunk and left and right pulmonary artery contents in each group were measured and analyzed statistically. RESULTS: The average CT value in the pulmonary thromboembolism group and postmortem clot group were (168.4±53.8) Hu and (282.7±78.0) Hu, respectively, which were lower than those of the control group (1 193.0±82.9) Hu (P<0.05). The average CT value of the postmortem clot group was higher than that of the pulmonary thromboembolism group (P<0.05). CONCLUSIONS: CT value is reliable and feasible as a relatively objective quantitative index to distinguish pulmonary thromboembolism and postmortem clot in postmortem CTPA. At the same time, it can provide a scientific basis to a certain extent for ruling out pulmonary thromboembolism deaths.

The value of PMCTA in the diagnosis of coronary atherosclerosis in isolated human hearts.

Postmortem computed tomography (PMCT) has a limited value in investigating coronary artery disease, despite several obvious advantages over the conventional autopsy. To address this issue, postmortem computed tomography angiography (PMCTA) has been introduced into various studies, where it has been used to investigate natural and unnatural deaths involving vascular damage, occlusion, or other pathologies of the vascular system. To investigate the application value of PMCTA in the diagnosis of coronary artery stenosis in ex situ hearts, the water-based contrast media were injected into isolated hearts, scaned, and finally compared with gold standards (autopsy and histology findings of the coronary artery). This study involved 16 subjects from the Academy of Forensic Science who were suspected to have died of sudden death without traumatic injuries. Unenhanced PMCT was performed first, followed by PMCTA using a water-based contrast agent, injected into the coronary arteries of isolated hearts using a self-designed angiography device. The image data were reconstructed into three-dimensional (3D) angiography images using software in the angiography facility. The 3D images were recorded and evaluated by two radiologists and then statistically analysed. The results of PMCTA were consistent with the gold standards for the diagnosis of coronary artery stenosis (P > 0.05). However, water-based contrast media can only be used to examine the pathological changes of blood vessels, which may have limitations in the diagnosis of causes of death such as myocardial oedema. PMCTA can be used as a new method to evaluate the degree of coronary atherosclerosis in addition to traditional autopsy. The 3D reconstruction technique reveals the coronary artery lesions more objectively and vividly and provides the opportunity to re-read the data at any time. Key points: The methods and parameters for coronary angiography in isolated human hearts were standardized based on the previous researcher.PMCTA in isolated human hearts is including the 3D reconstruction technique that reveals the coronary artery lesions more objectively and vividly, and provides the opportunity to re-read the data at anytime.PMCTA could only be used to examine the pathological changes of blood vessels, which might have limitations for the diagnosis of causes of death.PMCTA in isolated human hearts can be viewed as an auxiliary method for establishing the cause of death, which can provide an assessment of degree and extent of arterial stenosis and accurately help determine the abnormal location.

Pelvic Injury Discriminative Model Based on Data Mining Algorithm.

OBJECTIVES: To reduce the dimension of characteristic information extracted from pelvic CT images by using principal component analysis (PCA) and partial least squares (PLS) methods. To establish a support vector machine (SVM) classification and identification model to identify if there is pelvic injury by the reduced dimension data and evaluate the feasibility of its application. METHODS: Eighty percent of 146 normal and injured pelvic CT images were randomly selected as training set for model fitting, and the remaining 20% was used as testing set to verify the accuracy of the test, respectively. Through CT image input, preprocessing, feature extraction, feature information dimension reduction, feature selection, parameter selection, model establishment and model comparison, a discriminative model of pelvic injury was established. RESULTS: The PLS dimension reduction method was better than the PCA method and the SVM model was better than the naive Bayesian classifier (NBC) model. The accuracy of the modeling set, leave-one-out cross validation and testing set of the SVM classification model based on 12 PLS factors was 100%, 100% and 93.33%, respectively. CONCLUSIONS: In the evaluation of pelvic injury, the pelvic injury data mining model based on CT images reaches high accuracy, which lays a foundation for automatic and rapid identification of pelvic injuries.

Detection of traumatic internal carotid artery pseudoaneurysm by postmortem imaging: A case report.

RATIONALE: Postmortem imaging (PMI), including computed tomography (PMCT), postmortem computed tomography angiography (PMCTA), and postmortem magnetic resonance imaging (PMMRI), is rapidly becoming effective and a practical method in forensic medicine. This study aimed to present a specific forensic case in which the PMI approach and its applications were used. PATIENT CONCERNS: A 40-year-old male patient had moderate unilateral nose bleeding constantly 10 times after suffering from a head injury induced by a car accident. After a bilateral massive nose bleeding for the last time, he died from hemorrhagic shock. Traumatic internal carotid artery pseudoaneurysm (TICAP) was suspected in this patient. DIAGNOSIS, INTERVENTIONS, AND OUTCOMES: A whole-body scanning was performed using PMCT and PMMRI. Then, PMCTA using left ventricular cardiac puncture was also implemented. A water-soluble contrast agent was injected into the left ventricle and pumped toward the intracranial, followed by a repeated whole-body PMCT scan. The PMCT/PMMRI detected a high-density/signal mass inside the left sphenoid sinus. The PMCTA detected a distinct leakage of the contrast agent into the left sphenoid sinus from an adjacent aneurysm of the C3 section of the left internal carotid artery. Autopsy and histology confirmed a TICAP inside the sphenoid sinus. LESSONS: This case showed that the PMI was of great value for identifying the cause of death in special cases. When vascular lesions are suspected in the body, PMI and especially the PMCTA approach may be an effective detection method.

Traumatic extracranial internal carotid-jugular fistula leading to serious injury: a case report in forensic assessment.

Extracranial carotid artery injuries may produce severe haemorrhage, cerebral damage or arteriovenous fistula. Examples of traumatic extracranial carotid-jugular fistula are not frequently reported, especially in forensic medicine. We report a controversial case of an extracranial internal carotid-jugular fistula resulting from a stab wound to the neck. The degree of the injury was classified under "The Standard of Human Body Injury Assessment (2014)" (SIA) in China by forensic examiners. We believe this case report will provide information for the forensic assessment of similar cases.

Photonic generation of binary and quaternary phase-coded microwave signals by utilizing a dual-polarization dual-parallel Mach-Zehnder modulator.

A photonic method to generate binary and quaternary phase-coded microwave signals using a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) is proposed and experimentally demonstrated. The upper DPMZM driven by a radio frequency (RF) signal acts as an optical wavelength shifter, while the lower DPMZM is used to generate a binary phase shift key (BPSK) or quadrature phase shift key (QPSK) signal. By combining the wavelength-shifted optical sideband and phase-modulated optical carrier, both binary and quaternary phase-coded microwave signals can be generated. Such signals with the carrier frequency of 10 GHz and 15 GHz are demonstrated. The pulse compression performance is also investigated.

Subtentorial Meningioma Misdiagnosed as Cerebral Hemorrhage in Postmortem Computed Tomography Imaging: A Case Report.

This report presents a case of a 52-year-old man who had a traffic accident and died later. External examination could not determine the cause of death. Approximately 3 weeks later, an autopsy was performed. Postmortem computed tomography was performed before the autopsy. Postmortem imaging was interpreted to show hemorrhage beneath the tentorium, and the C5 to C6 (the fifth and sixth cervical vertebra) disc space was widened. During the autopsy, a cervical spinal cord injury was confirmed. However, a meningioma was found under the tentorium instead of a hemorrhage. There are a number of reasons that include postmortem changes that affected the virtopsy diagnosis, which still needs development.

Diagnosis of coronary artery disease using targeted post-mortem computed tomography coronary angiography: a case report.

Targeted post-mortem computed tomography (PMCT) combined with coronary angiography has the potential to play a significant role in the investigation of sudden cardiac death. The authors utilized a targeted PMCT coronary angiography in a case involving a 53-year-old man who died from acute myocardial ischemia and cardiac decompensation which may result from coronary artery disease (CAD). The victim collapsed suddenly at work and died soon after arrival to hospital. The body was examined using PMCT and targeted PMCT coronary angiography. The left anterior descending coronary artery exhibited 75%-100% stenosis in the middle segment; however, the distal segment could not be clearly visualized. In addition, the left circumflex and right coronary artery exhibited calcification, atherosclerosis and an area of 50% stenosis. Signs of cardiogenic pulmonary oedema were also identified. The imaging results suggested that this individual had coronary atherosclerosis and probably died from CAD. The autopsy and histological examination revealed acute myocardial ischemia and myocardial scarring, confirming the cause of death while excluding other probabilities. In summary, targeted post-mortem computed tomography angiography (PMCTA) can visualize the arteries and estimate the degree of principal pathological changes. This method is a simple, reliable and sensitive technique for identifying the presence of coronary atherosclerosis. It is a valuable post-mortem forensic imaging method and should be recommended in the investigation of suspicious cardiac deaths.