Forensic Imaging最新文献

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.

Microfocus Computed Tomography (Micro-CT) is a novel method for non-destructive 3D imaging of samples, reaching microscale resolutions. While initially prominent in material sciences for small samples, micro-CT now gains significance in biological and medical studies. Here we present our utilization of micro-CT for imaging large ex-vivo human samples for anatomical and forensic research in three recent experiments and discuss the fundamentals of micro-CT imaging.

For pelvic anatomical research, whole human pelvises were imaged to explore nerve anatomy around the prostate using various concentrations of buffered lugol (B-lugol). Advanced acquisition protocols were essential due to X-ray attenuation properties of the sample, which required higher energy for sufficient photon transmission.

For fetal research, B-lugol stained fetuses of 20–24 gestational weeks underwent full body imaging. However, this led to challenging acquisition parameters and images of insufficient quality. Subsequent destaining yielded less dense, yet contrast-maintaining samples allowing higher quality images. Refined acquisition protocols with reduced energy improved image quality.

For forensic research, explanted hyoid-larynx complexes were imaged. Micro-CT imaging showed potential in visualizing micro-fractures. The addition of B-lugol allowed for excellent soft tissue contrast and promising possibilities for forensic evaluation.

In conclusion, micro-CT imaging accommodates a diversity of large ex-vivo human samples for anatomical and forensic purposes, though challenges arise with optimal soft tissue staining and acquisition protocols. We describe partial destaining as a new possibility to alleviate scanning issues to improve scan quality and highlight topics for future research. Micro-CT imaging is a promising new avenue for medical research and forensic evaluation.

Purpose

Since many intraoral radiographs are taken in mass disasters, it is important to reduce the finger irradiation dose to the operator and caregivers in intraoral radiography. However, there is not enough reporting on finger irradiation doses when the detector is placed in the oral cavity of a corpse. The objective of this study was to examine finger irradiation doses when using detector holders and protective gloves and to compare various reduction methods.

Methods

One type of disposable and two types of protective gloves were employed in this study. The average irradiation dose was calculated by dividing the accumulated dose by the number of irradiation events for intraoral imaging of the left mandibular molar; since the dosimeter detects a cumulative dose, irradiation was continued until the dose exceeded 100 μSv. Statistical analysis was performed using one-way analysis of variance, Bonferroni test, and multiple comparisons test (α = 0.05).

Results

A significant dose reduction was observed using protective gloves (maximum: 63%, mean: 59%; p<0.01). No significant difference in the irradiation dose to the finger was observed when disposable gloves were layered on protective gloves. When protective gloves were used with the detector holder held at the end position, the radiation dose reduced by approximately 91% compared to when the detector was held directly in the oral cavity. Implementing these radioprotective measures can reduce the risks of increased radiation exposure and contamination.

Conclusions

The combined use of detector holders and protective gloves was effective in reducing the radiation exposure to the operator's fingers.

Background and objectives

Postmortem examinations of fetuses play a crucial role in confirming abnormalities, especially vascular and cardiac malformations leading to fetal demise. This study aims at developing and assessing a method for acquiring Post-Mortem CT-Angiography (PMCTA) with the injection of a lipophilic contrast agent (CA) to better visualize the great vessels of the trunk and head.

Materials and methods

25 human fetuses (gestational age at death between 106 days and 28 weeks) were included. Examinations were performed using a dual-energy Multidetector Computed Tomography (MDCT) scanner. Three imaging sequences were acquired, before CA injection, after injection of 7mL of CA through umbilical artery (arterial phase), and after an injection of 15mL of CA through umbilical vein (venous phase). CA-induced vascular opacification was scored per-vessel in both phases as follows: 0 = none, 1 = partial, 2 = complete. Total opacification was defined as the sum of the per-vessel opacification scores.

Results

In 23/25 subjects, CA injection into the umbilical vessels was feasible manually using flexible catheters. After the first injection, at least a partial opacification of the arterial network was achieved in 15/23 (65%) subjects. After the second injection, a complete opacification of the venous network was achieved in 18/23 (78%) subjects. Failures occurred in 10/25 (40%) subjects and were mostly due to the preservation status.

Conclusion

PMCTA performed with a two-phase intra-umbilical injection of a lipophilic CA enabled to visualize the vascular network, even after a significant a postmortem interval. This protocol may help in detecting vascular malformations, improving clinical diagnoses and prenatal counselling.

Introduction

In forensic radiology, the cardiothoracic ratio (CTR) calculated from postmortem computed tomography (PMCT) images can be used to detect cardiomegaly. In this study, a new measurement method is studied that involves measurement in the anteroposterior (AP) and transverse directions, with a reference level based on the Thai population.

Objective

To screen for cardiomegaly using the CTR calculated from PMCT images.

Research method

A sample size of 116 deceased Thai individuals who underwent PMCT before autopsy was obtained. Individuals were divided into two groups: normal heart weight and overweight heart. Hearts heavier than the mean plus one standard deviation were categorized into the overweight group. The CTR was calculated in both the AP and transverse directions at six reference levels. Receiver operating characteristic curves (ROC) were calculated to determine the CTR cutoff point for the diagnosis of cardiomegaly.

Results

The CTR cutoff values for diagnosing cardiomegaly were as follows: 1) CTR >0.5 in the transverse direction at the mid-vertebra of T7 (sensitivity, 75.6%; specificity, 70.6%; area under the ROC curve 0.81), 2) CTR >0.49 in the transverse direction at the mid-vertebra of T8 (sensitivity 71%, specificity 81.4%, area under the ROC curve 0.80). The selection of the cutoff values depended on the location of the heart. The area under the ROC curve in the AP direction was in the range 0.5-0.7, which is inferior compared to the transverse direction (0.7-0.9).

Conclusion

Calculating the CTR with a reference level on PMCT images can assist in the diagnosis of cardiomegaly.

In forensic anthropology, the probable identification of an unknown individual is based on the presence of quantifiable phenotypic variations and the relationship of these variations to the individual's socio-cultural identity. This study aims to create sub-specific discriminate shape matrices to estimate socio-cultural identity among a modern black South African sample, with a particular emphasis on developing standards for predicting mid-facial variation within this population.

The sample consists of 191 adult South Africans representing nine modern black South African socio-cultural identity groups obtained from the Pretoria Bone Collection in the Department of Anatomy at the University of Pretoria. Three-dimensional (3D) modelling of the relevant anatomical area was performed using an EinScan H 3D scanner. The 3D anatomical extraction was performed by placing 37 standard craniometric landmarks and 388 sliding landmarks on 3D models.

The analysis of variance associated with the linear model “shape against socio-cultural identity” explained 95.5% of overall shape variation showed that variations in midfacial shape configurations were statistically significant (MANOVA: p= 0.001; 50-50 MANOVA: p <2e-16) for all shape configurations, including sub-specific discriminate shape matrices, separately. Additionally, cross-validated linear discriminant function analysis yielded an accuracy between 73.01% and 91.53% for all shape configurations and sub-specific discriminant shape matrices, reflecting the discriminative power of socio-cultural identity groups in the black South African population.

Our findings support the utilization of geometric morphometric methods (GMM) for socio-cultural identity estimation as they allow us to retain the objects' geometry and statistically analyze subtle structural differences.