Forensic Imaging最新文献

Objectives

Materials and Methods

Results

Conclusion

Gunshot residues (GSR) analysis can be valuable in a forensic context for distinguishing entry wounds from exit wounds, especially in cases when body alterations prevent macroscopic analysis. Several studies have demonstrated its usefulness in various contexts. However, few studies have examined the retention of GSR under environmental conditions particularly after burial.

The primary objective of our experimental study is to investigate the retention of GSR after burial and decomposition by using two techniques: SEM-EDX and ICP-MS. Our secondary objective is to determine whether it is still possible to distinguish the entry wounds from the exit ones after 2 months of burial. For this study, we used a bovine model (cow feet), and fired with 7 mm semi-jacketed bullets. We formed several groups, including 3 control groups that hadn't been shot (buried for 2 days and 60 days and one unburied group), 3 test groups that had been shot (one unburied and two buried that were exhumed after 2 days and 60 days of burial).

The results of our study show that both SEM-EDX and ICP-MS were suitable for detecting particles characteristic of GSR, after 60 days of burial. However, only SEM-EDX could differentiate easily the entry wounds from the exit ones.

Our experimental study demonstrates that SEM-EDX analysis is suitable in cases where the discovery of a buried body doesn't allow the macroscopic determination of the ballistic trajectory.

It is well known that skeletal characteristics vary among different populations. Sex dimorphic characteristics of the mandible have been reported from studies using either mandible bone or computer tomography (CT) scan images of the mandible to test its efficacy in estimating sex. Mandibular studies for estimating sex in any particular population group may not hold well for different populations owing to inherent geographical variations. With this background, we assessed the validity of mandible measurements from CT scan images to determine sex in the South Indian population. As a part of our study, 11 metric parameters and 1 angular parameter were measured and analyzed. The mean values of all the parameters were significantly higher for males as compared to females. Bigonial breadth indicated the best discriminatory ability of the study. Mandibular angle had the least predictive accuracy among all the discriminant functions studied. We further observed that a combination of parameters gave the best overall classification rate (92.3 %). When the same functions were tested on an independent testing data set, a combination of parameters and bigonial breadth gave the best classification rate (82.1 %) which was consistent. We concluded that the mandible has a high accuracy for sex estimation. All the parameters studied demonstrated statistically significant differences between the two sexes except the mandibular angle.

Objectives

Sex determination is a critical step in personal identification. Both humerus and clavicle bones exhibit apparent sexual dimorphism in different populations. Multi-detector computed tomography (MDCT) scanning has been widely used in forensic sex estimation. It provides accurate bone measurements for the modern living population. This study aimed to develop a novel model to determine sex using MDCT scanning of humerus and clavicle bones in a sample of Egyptian population.

Material and Methods

Thoracic MDCT scans of 417 Egyptians of both sexes, aged 10-35 years were included. Three-dimensional volume rendering images were reconstructed using Vitrea® CT workstation. The vertical diameter of right humeral head (VDH) and right clavicular length (CL) were measured for each subject using Radiant DICOM viewer.

Results

Both measurements had significantly higher median values among males than females in all age groups above 15 years and were significantly valid for sex estimation. The highest AUC was reported for right VDH, followed by right CL (0.859 and 0.856, respectively). Optimal cut-off points of the right VDH and right CL for predicting males were >40.1 mm and >139.15 mm, respectively. Both studied measurements contributed significantly to univariate and multivariate regression models and gave rise to a novel model that could predict males with 83.5 % overall accuracy.

Conclusion

VDH and CL can be effectively used as an alternative in forensic sex estimation when only humerus and clavicle bones can be measured. The developed model can be easily applied by forensic specialists to estimate sex with high accuracy among Egyptian population.

Objectives

We encountered a case in which an acute subdural hematoma (SDH) was observed on postmortem computed tomography (PMCT) but no hematoma was found under the dura mater during autopsy. Subsequent verification led to the conclusion that the SDH was pressing on the brain when PMCT was performed but was not observed because all the subdural blood drained out during craniotomy because the hematoma did not clot.

Materials and Methods

We examined 13 cases of SDH in which PMCT was performed before autopsy to determine the factors related to the presence or absence of blood clots in the SDH, and to determine whether PMCT before autopsy could determine the presence or absence of blood clots in the SDH.

Results

Blood clots were not found in the SDH of individuals with an estimated survival interval of 5 h or less or when the estimated survival interval was 1440 h or more. No particular trend was observed in the relationship between the presence or absence of clots in the SDH and HU values of the SDH.

Conclusion

Early death after injury and chronic SDH are thought not to contain SDH clots. In cases of early death after injury, the autopsy diagnosis of SDH should be made by careful observation of the fluid SDH during craniotomy, as SDH may not contain clots as an indicator of SDH at autopsy. Predicting the presence or absence of a clot within an SDH using PMCT is difficult.

Conventional photogrammetry faces challenges with non-textured, transparent, or reflective surfaces, affecting accurate 3D modeling, particularly in forensic documentation. This study evaluates improvements using lower exposure, exposure bracketing, and RAW format for better 3D modeling of non-textured surfaces. Two bodies were photographed under controlled conditions to assess techniques for non-textured surfaces, with a comparison set for textured surfaces. The experiments were conducted in an autopsy room with a Nikon D5500 camera, adjusting for low exposure, exposure bracketing, RAW format, and increased photo redundancy. Models with Meshroom (Alicevision). Our focus was on visual plausibility rather than quantitative metrics. Results indicated that using RAW format with exposure bracketing and low exposure significantly improved 3D models by reducing artificial edges seen with standard JPG images, despite some noise. A redundant series of RAW photos further reduced edge artifacts and noise, demonstrating the effectiveness of averaging photos to enhance model quality. However, these modifications showed marginal improvements on textured surfaces, underscoring their significant benefits primarily for non-textured surfaces. This study highlights the potential of modified photogrammetry techniques in forensic science, particularly for documenting challenging surfaces. It points out the need for further research, given its limitations in sample size and the absence of extensive parameter testing and quantitative analysis.

Background

Approximately 170,000 individuals die annually in the Netherlands. Dutch law mandates examinations to distinguish between natural death and unnatural death. Traditionally, this involves external examinations and an inspection of medical records; however, medical imaging has emerged as a tool for investigating deaths.

Objective

The objective of the study was to investigate whether the addition of post-mortem magnetic resonance (PMMR) to post-mortem computed tomography (PMCT) could assist in the categorisation of deaths as natural or unnatural and augment confidence in those classifications.

Methods

In this retrospective study, the PMCT and PMMR head images of 50 individuals were evaluated by a forensic radiologist. The impact of PMMR on lesion detection, the cause of death (COD), the differentiation between natural death and unnatural death, and confidence levels were assessed. All available case information was used as the reference standard.

Results

The addition of the PMMR led to a statistically significant increase in lesion detection (48%), changes in the classification of COD in four cases, and an increased level of confidence in the classification. Differentiation between natural death and unnatural death reversed in 10 cases, altering the overall manner of death (MOD) classification in 20% of cases.

Conclusion

When PMCT indicates a natural or unnatural death, PMMR is unnecessary. PMMR of the head is recommended in situations in which the MOD is uncertain based on PMCT findings. The ultimate determination of a natural death and unnatural death should always take into account the results of external examinations, police investigations, and other available information.