Piece by piece-a computer-aided method for virtual re-association of commingled fragmented remains.

Air crashes or explosions with numerous victims may result in thousands of fragmented human remains that present a massive challenge for disaster victim identification teams. Genetic identification may present important financial and technical limits, and the physical re-association of fractured bones by forensic anthropologists may require a time-consuming phase of cleaning and drying. A virtual re-association (VRA) of fragmented human remains using postmortem computed tomography (CT)-scan images could enhance the identification process and reduce the number of genetic analyses required. Therefore, this study investigated the advantages and limitations of a VRA protocol in comparison with physical re-association (PRA) in a laboratory setting and in a real case scenario. As a first step, six porcine femurs were scanned by multi-detector CT before and after physical fragmentation. PRA of the dry bones and VRA of the 3D models of the fragments were then performed. The physically reconstructed dry bones were then once more scanned with CT. The mean distance between intact and reconstructed models, the number of re-associated fragments, and the time needed for the reconstruction were evaluated. In a second step, 87 fragmented remains resulting from a controlled pig bombing were collected, scanned, and virtually re-associated to test the feasibility of the protocol in a real context. The reconstruction of the femurs showed no difference in accuracy between PRA and VRA. Although the VRA was faster than PRA, the preparation of the material still needs to be taken into consideration. The VRA after the controlled pig bombing was limited to 8% of the total fragments. Differences in alveolar and cortical osseous structure and the presence of cartilage resulted in segmentation approximations and difficulties in the re-association itself. The explosion produced an important loss of intermediate bone elements. The VRA method still needs further evaluations with a larger sample size and different fragmentation mechanisms. However, the presented research shows promising results towards enhancing the efficiency of identifying individuals after a mass disaster. Key points: Mass disasters with highly fragmented bodies represent a major challenge for the disaster victim identification (DVI) teams.Using CT-scans of the fragments, a virtual re-association method could enhance the DVI process and reduce the number of genetic analysis required.A laboratory setting using porcine femurs shown that the VRA process could start earlier and was faster than the physical re-association.Although methodological limits were highlighted, and the efficiency of the method has to be re-evaluated, the controlled bombing showed that the VRA could be applied in a real case scenario.

A pilot study to identify suitable MRI protocols for preoperative planning of total hip arthroplasty.

PURPOSE: The purpose of this study is to identify suitable MRI sequences and evaluate the feasibility and performance of MRI for total hip arthroplasty (THA) preoperative planning. METHOD: A multicentric pilot study was conducted to evaluate DP TSE and T1 GRE 3D sequences. High-resolution pelvis, hip, knee and ankle images were acquired. Protocols were optimised to enhance image quality (IQ) and reduce acquisition time to fit clinical practice. The final protocol was validated with 19 healthy volunteers with variable BMIs at 1.5 and 3 Tesla. Visual assessment was performed by five radiographers and radiologists using the ViewDEX software. Visual Grading Analysis (VGA), Intraclass Correlation Coefficient (ICC), Prevalence-adjusted and bias-adjusted kappa (PABAK) and Visual Grading Characteristics (VGC) were performed to analyse data. RESULTS: VGA scores indicated that the optimised 3D DP TSE and 3D T1 GRE sequences at 3 T, as well as 3D DP TSE sequence at 1.5 T offer adequate IQ and allow a correct visualisation of the anatomy. Overall ICC analysis was moderate to good reliability at 0.749 (95 % CI 0.69-0.79) and increased from good to excellent at 0.846 (95 % CI 0.72-0.91) for DP at 3 T. PABAK shows fair agreement at 0.25 (95 % CI 0.227-0.273). VGC analysis showed that 3D DP TSE sequences performed statistically better than 3D T1 GRE at 1.5 and 3 T (p-value ≤ 0.05). Furthermore, 3 T sequences showed a statistically better performance compared to 1.5 T (p-value ≤ 0.05). CONCLUSIONS: According to the results, 3D DP and T1 MRI sequences can be considered for preoperative planning for THA. Further research is required to emphasize the clinical validation of the results.

Impact of increasing levels of adaptive statistical iterative reconstruction on image quality in oil-based postmortem CT angiography in coronary arteries.

INTRODUCTION: Postmortem multi-detector computed tomography (PMCT) has become an important part in forensic imaging. Modern reconstruction techniques such as iterative reconstruction (IR) are frequently used in postmortem CT angiography (PMCTA). The image quality of PMCTA depends on the strength of IR. For this purpose, we aimed to investigate the impact of different advanced IR levels on the objective and subjective PMCTA image quality. MATERIAL AND METHODS: We retrospectively analyzed the coronary arteries of 27 human cadavers undergoing whole-body postmortem CT angiography between July 2017 and March 2018 in a single center. Iterative reconstructions of the coronary arteries were processed in five different level settings (0%; 30%; 50%; 70%; 100%) by using an adaptive statistical IR method. We evaluated the objective (contrast-to-noise ratio (CNR)) and subjective image quality in several anatomical locations. RESULTS: Our results demonstrate that the increasing levels of an IR technique have relevant impact on the image quality in PMCTA scans in forensic postmortem examinations. Higher levels of IR have led to a significant reduction of image noise and therefore to a significant improvement of objective image quality (+ 70%). However, subjective image quality is inferior at higher levels of IR due to plasticized image appearance. CONCLUSION: Objective image quality in PMCTA progressively improves with increasing level of IR with the best CNR at the highest IR level. However, subjective image quality is best at low to medium levels of IR. To obtain a "classic" image appearance with optimal image quality, PMCTAs should be reconstructed at medium levels of IR.

Neck-MRI experience for investigation of survived strangulation victims.

For the medicolegal evaluation of victims of survived strangulation, a neck-magnetic resonance imaging (MRI) can be performed for assessing lesions in the inner soft tissues (fat, muscles or lymph nodes, for example). In our institute, such MRI examinations have been performed for a test period of 4 years with the aim of evaluating the use of this tool by forensic pathologists and identifying medicolegal indicators for the performance of neck-MRI in surviving victims of strangulation. We retrospectively reviewed medicolegal reports from all victims examined during the test period. We extracted objective lesions (e.g. petechiae, bruising and abrasions) and reported clinical symptoms (e.g. vision disorder, dysphasia) from the reports. These findings were compared to those reported from the neck-MRI. In total, 112 victims were clinically examined after suspected strangulation. Eleven of these victims underwent an MRI examination of the neck. Eighty-four of the victims presented objective lesions during the clinical examination, with eight showing signs of both petechiae and bruising. Neck-MRI was performed in four of these eight victims and three of them showed lesions visible in MRI. Of 76 victims with bruising as the only objective finding, 66 victims described clinical symptoms. Of those 66 victims, seven were examined by MRI and two demonstrated lesions in MRI. When MRI was performed, relevant findings were detected in 45% of the cases. This leads to the suspicion that many more findings could have been detected in the other victims, if an MRI had been performed in those cases. Our results lead us to the conclusion that an MRI examination of victims of suspected strangulation is useful, and strict indications for its application should be established.

Oleic Acid (OA), A Potential Dual Contrast Agent for Postmortem MR Angiography (PMMRA): A Pilot Study.

Choosing proper perfusates as contrast agents is an important aspect for postmortem magnetic resonance angiography (PMMRA). However, in this emerging field, the number of suitable kinds of liquid is still very limited. The objective of this research is to compare MR images of oleic acid (OA) with paraffin oil (PO) in vitro and in ex situ animal hearts, in order to evaluate the feasibility to use OA as a novel contrast agent for PMMRA. In vitro, OA, PO and water (control) were introduced into three tubes separately and T1weighted-spin echo (T1w-SE) and T2w-SE images were acquired on a 1.5T MR scanner. In the second experiment, OA and PO were injected into left coronary artery (LCA) and left ventricle (LV) of ex situ bovine hearts and their T1w-SE, T2w-SE, T1w-multipoint Dixon (T1w-mDixon) and 3DT2w-mDixon images were acquired. The overall results indicate that OA may have a potential to be used as a dual (T1 and T2 based) contrast agent for PMMRA when proper sequence parameters are utilized. However, as the pilot study was based on limited number of animal hearts, more researches using OA in cadavers are needed to validate our findings.

Temperature dependence of viscosity, relaxation times (T1, T2) and simulated contrast for potential perfusates in post-mortem MR angiography (PMMRA).

Developments in post-mortem imaging increasingly focus on addressing recognised diagnostic weaknesses, especially with regard to suspected natural deaths. Post-mortem MR angiography (PMMRA) may offer additional diagnostic information to help address such weaknesses, specifically in the context of sudden cardiac death. Complete filling of the coronary arteries and acceptable contrast with surrounding tissue are essential for a successful approach to PMMRA. In this work, the suitability of different liquids for inclusion in a targeted PMMRA protocol was evaluated. Factors influencing cooling of paraffinum liquidum + Angiofil® (6 %) in cadavers during routine multiphase post-mortem CT angiography were investigated. The temperature dependence of dynamic viscosity (8-20 °C), longitudinal (T1) and transverse (T2) relaxation (1-23 °C) of the proposed liquids was quadratically modelled. The relaxation behaviour of these liquids and MR scan parameters were further investigated by simulation of a radiofrequency (RF)-spoiled gradient echo (GRE) sequence to estimate potentially achievable contrast between liquids and post-mortem tissue at different temperatures across a forensically relevant temperature range. Analysis of the established models and simulations indicated that based on dynamic viscosity (27-33 mPa · s), short T1 relaxation times (155-207 ms) and a minimal temperature dependence over the investigated range of these parameters, paraffin oil and a solution of paraffin oil + Angiofil® (6 %) would be most suitable for post-mortem reperfusion and examination in MRI.

Tearing of the left iliac vessels in lumbar surgery revealed by multiphase post-mortem CT-angiography (MPMCTA).

Lumbar surgery is regularly applied in cases of discal hernia and acquired lumbar stenosis. In this report, we present a case of a laceration in the left common iliac artery and iliac vein during a lumbar surgery and discuss the literature concerning this kind of event. In the present case, the surgical procedure was followed by a sudden decrease in blood pressure, and the surgeon discovered an intra-abdominal haemorrhage that led to the patient's death. Postmortem investigation confirmed the intra-abdominal haemorrhage and revealed a laceration of the proximal portion of the left common iliac artery and left iliac vein. The source of bleeding could be detected especially thanks to multi-phase postmortem CT angiography (MPMCTA), which was performed prior to autopsy. We also found a haemorrhagic path through the intervertebral disc between the L4-L5 vertebrae, caused by the surgeon's instrument (pituitary rongeur). To date, a few cases have been described of iatrogenic death resulting from a tear in the iliac vessels during lumbar surgery, but not from the postmortem perspective. Such investigations have recently been modernized thanks to the introduction of forensic imaging. In particular, MPMCTA offers new possibilities in postmortem investigations and can be considered the new gold standard for investigating deaths related to medical intervention. Here we describe the first case of a death during lumbar surgery using this new method.

Performance of post-mortem CT compared to autopsy in children.

INTRODUCTION: Radiological techniques such as non-enhanced post-mortem computed tomography (PMCT) play an increasingly important role in death investigations, especially in cases of non-medicolegal context of death, where the consent of the next of kin is required to perform autopsy. Such consent is often difficult to obtain for deceased children, and radiological methods may be an acceptable alternative. The aim of our study was to evaluate the performance of PMCT explorations compared to medicolegal conventional autopsies in children and its potential usefulness in non-medicolegal situations. METHODS: We retrospectively reviewed a group of 26 children aged 0-12 years who died of different causes, which were investigated by both conventional autopsy and PMCT. We compared the findings extracted from radiological and autopsy reports. All findings were grouped according to their importance with respect to cause of death and to the anatomical structure they covered: organs, vascular system, soft tissue, and skeletal system. RESULTS: A significantly larger number of findings were detected by autopsy compared to PMCT. Autopsy proved to be superior to PMCT, notably at detecting organ, soft tissue, and vascular findings, while PMCT was superior at detecting bone findings. However, no statistically significant differences were found between the methods concerning the essential findings used to define the cause of death. CONCLUSIONS: In children, PMCT was less sensitive than conventional autopsy for detecting general findings. However, most essential findings were detected by both methods. PMCT was superior to autopsy for the detection of bone lesions in children. ADVANCES IN KNOWLEDGE: Up to today, very rare literature exists concerning PMCT in children, especially in a forensic setting. This article investigates the advantages and limitations of PMCT compared to autopsy in a unique study group and discusses possibilities for future developments.

The forensic radiographer: a new member in the medicolegal team.

Multidetector computed tomography is becoming more widespread in forensic medicine. In most services, autopsy assistants perform the radiological examination. We introduced professional radiographers into the legal medicine service and hypothesized they would also be able to take over duties currently reserved for other specialists. The aims of this study were to evaluate if radiographers could be trained as "forensic radiographers" by (1) integrating graduated medical radiographers into the legal medicine service, (2) investigating the advantages of this collaboration, and (3) defining the duties of the forensic radiographers.The study was performed prospectively on a group of 8 recruited radiographers who underwent a testing period with special training. They learned the basics of medicolegal case treatment, the autonomous execution of postmortem computed tomography angiography, and postprocessing of data. Seven of 8 radiographers finished the training and were integrated into our service. Although all radiographers were able to fulfill the duties demanded after the training period, some radiographers could not enter or complete the program because they were unable to work with dead bodies.Our study presents the advantages of integrating radiographers into the medicolegal team and proposes how to train the forensic radiographers. In addition, the duties and responsibilities of these new specialists are defined.