Forensic Imaging最新文献

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.

Post-mortem computed tomography (PMCT) is a diagnostic tool that provides essential information in forensic field. This radiological technique can play a pivotal role in personal identification, gunshot injuries, major traumatic injuries, child abuse, drowning asphyxia, embolism, COVID-19, sudden death, and charring cases.

Post-mortem imaging can be used to investigate charred bodies as it allows the forensic examiner to distinguish traumatic and heat injuries. PMCT images can also provide additional information to determine whether the individual was alive at the time the fire started.

In our bicentric study, we performed PMCT on 15 cases of charred bodies (10 males and 5 females) collected at the Florence University (Florence, Italy) and Catholic University of The Sacred Heart (Rome, Italy) before the external examination and/or full autopsy examination. In both the institutions, PMCT was performed through a Siemens SOMATOM 16-slice CT scanner (Siemens Aktiengesellschaft, Berlin, 2010).

The aim of the current study was to obtain unambiguous information that could help determine the cause of death by comparing our PMCT findings with the most recent evidence in the scientific literature. Our investigations focused on the evaluation of bone texture and differences from traumatic fractures, leading also to an improvement in the interpretation of some aspecific findings (e.g., soot) from the integration of the radiological information with the autopsy results.

The data obtained in our study support PMCT as a reliable diagnostic tool in the study of charred corpses and represent basic evidence for further applications of radiology in the forensic field.

Objectives

variations in the positions of organs and bones resulting from two different body positions during PMCT were investigated.

Methodology

Forty-four bodies were CT-scanned in two positions and compared using 18 landmarks and 27 distances.

Results and conclusion

Differences below 1 cm were observed for all measurements. The most significant variation was observed along the cranio-caudal plan (z). Awareness of these movements is important when using 3D models for visualization or 3D reconstructions.

Filtering is known to improve image quality of CT scans. Water immersion is one type of filtering that has been used for CT scanning dry (skeletonized) bones, and it has been suggested that this approach can increase measurement accuracy and improve fracture resolution. These tests have previously involved clinical CT scanners. Here we use an industrial micro-CT scanner and test whether water immersion and other x-ray filtering options increases fracture resolution in reconstructed scans of dry bones.

Eleven dry non-human bones were CT scanned using the same acquisition parameters, while varying filter options. Bones were scanned (1) in an unfiltered “dry” air environment, (2) using metal filters at the x-ray source, and (3) with the bones immersed in water. A small subset of bones (N = 3) was also scanned using the same parameters except increasing the number of projections acquired from 500 to 1500. Reconstructed scans were evaluated by the authors, in part using a Likert scale comparing filtered with unfiltered scans, to assess fracture resolution (overall appearance and extent).

Results showed that increasing the projections resulted in the greatest improvement in fracture resolution, followed by filtering at the x-ray source. Water immersion performed poorly overall, possibly due to movement artifacts that result from this type of scanning, in which the specimen rotates on a stage during the scan. When using this type of CT scanner, if increased fracture resolution is desired, water immersion is not recommended; increasing the number of projections or filtering at the x-ray source is suggested instead.

Objectives

In quantitative postmortem computed tomography (qPMCT) the presence of putrefaction gas in tissues can obscure measurements such as bone mineral density (BMD). Quantitative CT analysis procedures adopted directly from clinical CT may not be designed to compensate for intracorporeal gas, which require additional measures for PM-imaging applications. Thus, a solid unbiased procedure for volumetric BMD analysis in PMCT of the deceased presenting with intracorporeal gas is desirable.

Materials and methods

We tested three different analysis procedures (AP1-3) for BMD analysis of the lumbar vertebrae (L1-3). Data in this retrospective study was based on synchronous PMCT acquisition with a solid five-phase Cann-Genant phantom from routine forensic examinations of 154 individuals distributed into three putrefaction groups: “None” (n = 95), “Mild” (n = 54), and “Moderate” (n = 10). AP1 was based on commercially available software (“Mindways”), which required the operator to subjectively place region of interest (ROIs) in areas without gas. The open-source software (“FIJI”) was used for AP2 and AP3 and enabled comparison of objectively placed ROIs with AP1. In AP3, threshold-filtering was applied to remove the signal from gas (in AP2 data) prior to BMD analysis.

Results

AP1 provided higher BMD values than AP2-3 due to subjective placement of ROIs in denser cortical areas. AP2 yielded the lowest BMD measurements with most variation, while AP3 yielded BMD measurements comparable to in vivo values published in clinical studies. AP3 provided greater interobserver correlation.

Conclusion

AP3 provided a simple open-source software-based approach to PMCT BMD analysis that allows for precise BMD measurements in PMCT.

Objectives

Injuries caused by animal abuse are termed non-accidental injuries, and should be distinguished from accidental injuries. We compared postmortem computed tomography (PMCT) and necropsy findings in deceased cat bodies suspected of having been abused to determine whether findings previously reported to be associated with abuse or accident could be ascertained by necropsy or PMCT.

Materials and methods

Seven deceased cat bodies requested by the police for necropsy because of suspicion of animal abuse were used to compare necropsy and PMCT findings.

Results

PMCT revealed gas distribution abnormalities, such as pneumocephalus and pneumothorax, and bone lesions findings, such as cervical and pelvic fracture; however, several of these were not confirmed at necropsy. Findings such as liver contusion and injury to the posterior vena cava were confirmed only by necropsy and not by PMCT. Findings related to animal abuse, i.e., ocular injuries, skull, bilateral rib, and femoral fractures were confirmed by both PMCT and necropsy in 3, 5, 2, and 2 cats, respectively. Pneumothorax, pelvic fracture, and sacroiliac luxation, related to accidents, were confirmed only by CT in 6 of 6, 1 of 4, and 2 of 2 bodies.

Conclusion

PMCT revealed gas- and some bone-related findings more efficiently than necropsy, and a combination of PMCT and necropsy is recommended to perform, particularly if the death circumstances is unknown.