Postmortem CT in Trauma: An Overview

A computational approach to estimate postmortem interval using postmortem computed tomography of multiple tissues based on animal experiments

The estimation of postmortem interval (PMI) is a complex and challenging problem in forensic medicine. In recent years, many studies have begun to use machine learning methods to estimate PMI. However, research combining postmortem computed tomography (PMCT) with machine learning models for PMI estimation is still in early stages. This study aims to establish a multi-tissue machine learning model for PMI estimation using PMCT data from various tissues. We collected PMCT data of seven tissues, including brain, eyeballs, myocardium, liver, kidneys, erector spinae, and quadriceps femoris from 10 rabbits after death. CT images were taken every 12 h until 192 h after death, and HU values were extracted from the CT images of each tissue as a dataset. Support vector machine, random forest, and K-nearest neighbors were performed to establish PMI estimation models, and after adjusting the parameters of each model, they were used as first-level classification to build a stacking model to further improve the PMI estimation accuracy. The accuracy and generalized area under the receiver operating characteristic curve of the multi-tissue stacking model were able to reach 93% and 0.96, respectively. Results indicated that PMCT detection could be used to obtain postmortem change of different tissue densities, and the stacking model demonstrated strong predictive and generalization abilities. This approach provides new research methods and ideas for the study of PMI estimation.

Normal Distal Tibiofibular Syndesmosis Assessment Using Postmortem Computed Tomography (PMCT)

BACKGROUND

Distal tibiofibular syndesmotic injuries, often misdiagnosed, can lead to substantial morbidity. This study utilized postmortem computed tomography (PMCT) to define normal syndesmotic relationships in 131 subjects.

METHODS

Three parameters were measured: fibular rotation (FR), sagittal translation (ST), and incisura depth (ID).

RESULTS

Interobserver reliability was excellent for FR and ID but moderate for ST. Anatomical variability was wide, with FR ranging from -0.4° to 16.6°, ST from 0.33 mm to 3.49 mm, and ID from 1.89 mm to 6.05 mm. Side-to-side variability within subjects was minimal. Gender-specific differences were observed in ST, possibly due to size variations, highlighting the need for gender-specific diagnostic criteria.

CONCLUSIONS

Although establishing universal reference values is challenging, using contralateral ankles for comparison can enhance diagnostic accuracy in syndesmotic injuries. This study, the first of its kind, offers valuable insights into normal distal tibiofibular syndesmotic relationships based on PMCT data. Future validation studies in patients with syndesmotic injuries can further improve diagnostic accuracy.

Post-mortem CT in the investigation of homicides

AIM

To investigate the reliability of post-mortem computed tomography (PMCT) in a case series of homicides involving blunt-force, sharp-force, and ballistic trauma.

MATERIALS AND METHODS

The study investigates 16 homicide cases that underwent PMCT before autopsy. Two radiologists assessed the PMCT examinations and the data were compared to the forensic pathology findings. Data were organised in broad categories: foreign bodies, external injuries, soft-tissue and organ injuries, fractures, air in cavities, fluid collections, random pathology, and wound track. Findings were organised by systems: head and neck, thorax, abdomen and pelvis, extremities. Cohen's kappa statistics were used to assess observer agreement.

RESULTS

Six gunshot-related homicides (37.5%), seven sharp-force-related homicides (43.75%), two blunt-force-related deaths (12.5%), and one homicide due to mechanical asphyxia (1.25%) were analysed. A total of 64 fractures were reported by the pathologists, 67 by radiologist 1 and 68 by radiologist 2. Agreement was deemed substantial in all cases. Pathologists failed to report gas in cavities while radiologists underreported superficial injuries.

CONCLUSION

An overall observation was that less accurate findings were produced by the blinded radiologist in comparison to the non-blinded one. The extremeness of homicides obscured the interpretation of PMCT leading to the observed discrepancies. The combination of PMCT and autopsies is deemed optimal when investigating homicidal events.

Suspension-associated dislocation of the jaw in hanging

Hanging is a common type of death, and the role of the medical investigation of such deaths by a forensic pathologist not only requires the determination of the cause of death but providing information to assist in the determination of the manner of death. The forensic pathologist should be well versed in the spectrum of injuries known to be associated with neck compression, to document injuries known to be associated with hanging, but also to identify those that are inconsistent with self-inflicted hanging or that may suggest the involvement of a third party in the death. Comprehensive identification and correct interpretation of external and internal injury are crucial for the appropriate degree of police and coroner/medical examiner investigation. We present two cases of deaths believed to be caused by self-inflicted hanging that were observed to have unexpected unilateral dislocation of the temporomandibular joint identified on routine post-mortem computed tomography, without any evidence of involvement of a third party. This injury was unexplained and had not been previously observed at our Forensic Institute nor was it identified after a review of the published biomedical research literature. Issues regarding the cause of this abnormality, possible mechanisms, and the medicolegal significance of this finding will be discussed.

Post-traumatic cerebral infarction caused by thrombus in the middle cerebral artery

A woman in her 80s was found unconscious after being hit by a car while crossing a road. After admission to hospitals, computed tomography (CT) scans revealed traumatic brain injury (TBI), and the patient was treated symptomatically. However, despite improvement of TBI in CT images, she died unexpectedly. Postmortem CT demonstrated cerebral infarction in the territory of the right middle cerebral artery (MCA). Histopathological examination revealed lumen-obstructing thrombosis and intimal injury upstream of the thrombosis in the right MCA. These findings suggested that the intimal injury in the MCA had led to thrombus formation, and thromboembolism in the region distal to the injury leading to post-traumatic cerebral infarction (PTCI). Both postmortem CT and autopsy were able to reveal the final condition of the deceased, which had not been fully anticipated by the clinicians who had treated her after the accident. The longitudinal antemortem to postmortem course revealed by multiple CT images and the histopathological examination provided crucial clues to the pathogenesis of PTCI in this case.

Post-Mortem CT Delivers Fast and Accurate Injury Identification in Trauma Patients

Background

Accurate and timely injury identification is critical but difficult to achieve in trauma patients who die shortly after arrival to the hospital. Autopsy has historically been used to detect injuries, but few undergo formal autopsy. This study investigates the utility of post-mortem computed tomography (PMCT) for injury identification in a diverse trauma population.

Methods

Cross-sectional study of adult trauma patients who died within 24 hours of arrival to a Level I trauma center were included. Among patients with PMCT, injury severity score (ISS) and number of injuries (NOI) were calculated either from physical exam alone (pre-PMCT) or exam and imaging (post-PMCT). ISS and NOI before and after PMCT were compared. A cause of death analysis was performed for patients who underwent comprehensive (ie, head, neck, and torso) PMCT. Non-parametric repeated measures tests were used, as appropriate.

Results

7.3% (N = 28) of patients received PMCT. Compared to pre-PMCT, median ISS (21 vs 3.5) and NOI (5 vs 2) were greater post-PMCT ( P < .001, respectively). Autopsy rate was 13.2% overall; 82.5% of autopsies were due to a penetrating mechanism, and median time to autopsy reporting was 38.5 days. Among 17 patients who received comprehensive PMCT, 64.7% had a single cause of death identified, and the remaining were classified as either multiple potential contributors or unknown.

Discussion

PMCT is a readily available method to identify injuries in trauma patients who expire shortly upon presentation. Given the low autopsy rate for blunt trauma and delay in reporting, PMCT is an important adjunct for trauma providers.

Estimation of the time of death by measuring the variation of lateral cerebral ventricle volume and cerebrospinal fluid radiodensity using postmortem computed tomography

Using postmortem CT (PMCT), changes in the volume of the lateral cerebral ventricles (LCVs) and modifications of the radiodensity of cerebrospinal fluid (CSF) have been examined to identify a possible relationship between these changes and the time of death. Subsequent periodical CT scans termed "sequential scans" for ten corpses at known time of death were obtained, and a 3D segmentation of the entire LCV was carried out to measure its volume and radiodensity over time from ~ 5.5- h up to 273-h postmortem. A linear decrease of the LCV volume for all the cases was observed in the investigated time range, together with an overall logarithmic increase of radiodensity. Although a larger sampling should be performed to improve the result reliability, our finding suggests that the postmortem variation of CSF radiodensity can be a potentially useful tool in determining postmortem interval, a finding that is worthy of further investigation.

[Organization of postmortem radiological examination in the structure of pathological departments and forensic bureaus]

The purpose of this work is to develop an optimal scheme for organizing and conducting postmortem radiation studies in the Russian Federation based on literature data and our own results. One of the primary points in organizing virtopsiy is to determine the place where radiation examinations of deceased patients will be performed. The absence or presence of the equipment and capabilities available in the institution, i.e., the department of radiation diagnostics with functioning CT and MRI devices and software, determines the volume of economic costs. The analysis of the results of radiation research methods should be carried out by a highly qualified radiologist who has both general knowledge of radiation diagnostics and information about the radiation pattern of nonspecific postmortem changes. Based on our own experience in organizing postmortem radiation examinations, we consider it optimal to conduct postmortem CT and/or MRI scans by an X-ray technician in the radiation diagnostics department and to introduce a separate radiologist in the staffing of the pathology department or forensic medical examination bureau. In our opinion, an examination of the corpse by a radiologist in conjunction with a forensic expert is required to determine the most important areas of interest, tactics and methodology of radiation research. The final conclusion of the radiologist should be formed after consultation and agreement of the identified changes with a pathologist or forensic expert. Virtopsy is a highly effective objective method for examining a corpse. This dictates the need for its widespread introduction into the practice of the forensic medical examination bureaus and pathological and anatomical departments.

Unenhanced PMCT in the diagnosis of fatal traumatic brain injury in a charred body

Traffic incidents are one of the most frequent causes of death in young adults worldwide. Depending on the location of the incident, the velocity of the vehicle(s), the weather condition, traffic incidents are often complicated making the investigation of the circumstances difficult. Here we report a case of an incinerated body involved in a vehicle incident. Differential diagnosis included natural cause of death during driving, fatal traumatic injuries, death due to fire and positional asphyxia. The body was submitted to PMCT prior to autopsy as part of a research protocol (N. 1388/2016) at the Department of Medical Imaging of the University Hospital of Heraklion in Crete, Greece. Unenhanced PMCT revealed craniofacial fractures, a thin film of subdural haemorrhage and an epidural fluid collection. The findings were interpreted as consistent with an impact to the face, causing craniofacial fractures mainly on the right side, and an acute subdural hematoma. Autopsy findings corroborated the diagnosis. The epidural hematoma was deemed to be post-mortem heat-induced. This case is an excellent example of the diagnostic value of PMCT in the medicolegal investigation of death.

A Guide to Mass Casualty Incidents for Radiology Residents: Strategies, Ethics, Directions

Mass casualty incidents, by nature of their scale and unpredictability, can rapidly overwhelm health infrastructure. Preparation is the key to managing these crises with the lowest risk to emergency and health personnel, while providing maximal life saving measures. We present an overview of the multitiered planning that should go into forming a well set out emergency response plan and one that is capable of being adapted to a wide range of mass casualty scenarios. We highlight the ethical implications that a healthcare team faces while making challenging decisions rapidly in a high-pressure environment. Radiology trainees should be aware of the response systems in place at their institutions and the role that is expected of them in mass casualty incidents.