Post-mortem computed tomography: Technical principles and recommended parameter settings for high-resolution imaging

Photon-counting CT for forensic death investigations-a glance into the future of virtual autopsy

This article explores the potential of photon-counting computed tomography (CT) in forensic medicine for a range of forensic applications. Photon-counting CT surpasses conventional CT in several key areas. It boasts superior spatial and contrast resolution, enhanced image quality at low x-ray energies, and spectral imaging capabilities that enable more precise material differentiation. These advantages translate to superior visualization of bone structures, foreign bodies, and soft tissues in postmortem examinations. The article discusses the technical principles of photon-counting CT detectors and highlights its potential applications in forensic imaging, including high-resolution virtual autopsies, pediatric forensic CT, trauma analysis, and bone density measurements. Furthermore, advancements in vascular imaging and soft tissue contrast promise to propel CT-based death investigations to an even more prominent role. The article concludes by emphasizing the immense potential of this new technology in forensic medicine and anthropology.

Magnetic resonance imaging of regional gray matter volume in persons who died by suicide

In vivo neuroimaging research in suicide attempters has shown alterations in frontal system brain regions subserving emotional regulation, motivation, and self-perception; however, data from living individuals is limited in clarifying risk for suicide death. Postmortem neuroimaging provides an approach to study the brain in persons who died by suicide. Here, whole brain voxel-based analyses of magnetic resonance imaging gray matter volume measures were performed comparing persons confirmed by forensic investigation to have died by suicide (n = 24), versus other causes (n = 24), in a univariate model covarying for age and total brain volume; all subjects were scanned within 24 hours after death. Consistent with the hypothesis that persons who died by suicide would show lower gray matter volume in frontal system brain regions, this study of suicides showed lower gray matter volume in ventral frontal and its major connection sites including insula, striatum, and amygdala.

A Case of Hanging with Limited Specific Postmortem Brain Imaging

In Japan, the number of autopsies has steadily decreased. Therefore, postmortem imaging methods have positioned as valuable supplemental or complementary tools in autopsy procedures. We clinicians are increasingly faced with the need to infer cause of death from postmortem imaging findings. We report computed tomography (CT) and magnetic resonance imaging (MRI) findings of a 41-year-old man who committed suicide by hanging. CT revealed fractures of the left superior horn of the thyroid cartilage. Head MRI showed high signal intensity in the basal ganglia on the T1-weighted image and high-intensity rims along the cerebral cortex on the diffusion-weighted image; however, these were considered normal postmortem changes. There were no significant findings in the heart, major blood vessels, or abdominal organs. The contents of the stomach were minimal, and no tablets or other evidence suggestive of drug overdose were identified. Traumatic changes were not observed. Based on the scene and his circumstances, it was speculated that he died by hanging and an autopsy was not performed. This case highlights the importance of understanding normal postmortem brain imaging changes to estimate the true cause of death.

Postmortem CT and MRI for detecting bowel obstruction in cases of pediatric sepsis deaths

This article describes the utility of postmortem CT and MRI in diagnosing pediatric bowel obstruction (BO) as the cause of septic shock-induced death. Six pediatric cases with confirmed septic shock were retrospectively analyzed. Postmortem CT scans revealed clear signs of BO in all cases, with volvulus, intussusception, diaphragmatic hernia, or Meckel's diverticulum identified. MRI scans, performed in three cases, did not provide additional diagnostic information. The presented case series highlights the potential of postmortem CT for diagnosing BO in children, potentially aiding in understanding the cause and manner of death. While MRI offered limited additional benefits, its role in conjunction with CT and autopsy warrants further exploration. Combining these modalities could enhance diagnostic accuracy and provide a more complete picture of the cause of death in children.

Gray-Scale Extraction of Bone Features from Chest Radiographs Based on Deep Learning Technique for Personal Identification and Classification in Forensic Medicine

Post-mortem (PM) imaging has potential for identifying individuals by comparing ante-mortem (AM) and PM images. Radiographic images of bones contain significant information for personal identification. However, PM images are affected by soft tissue decomposition; therefore, it is desirable to extract only images of bones that change little over time. This study evaluated the effectiveness of U-Net for bone image extraction from two-dimensional (2D) X-ray images. Two types of pseudo 2D X-ray images were created from the PM computed tomography (CT) volumetric data using ray-summation processing for training U-Net. One was a projection of all body tissues, and the other was a projection of only bones. The performance of the U-Net for bone extraction was evaluated using Intersection over Union, Dice coefficient, and the area under the receiver operating characteristic curve. Additionally, AM chest radiographs were used to evaluate its performance with real 2D images. Our results indicated that bones could be extracted visually and accurately from both AM and PM images using U-Net. The extracted bone images could provide useful information for personal identification in forensic pathology.

Pediatric forensic postmortem computed tomography: basics to advanced

The approach to postmortem computed tomography (CT) differs significantly from that of diagnostic CT in living patients. Elimination of artifacts such as noise and beam hardening as well as optimization of tissue contrast requires alteration of exposure parameters from protocols designed to limit radiation dose in children. Multiple scans may be performed, and detailed post-processing can be used to enhance subtle findings such as small intracranial extra axial collections and non-displaced fractures. Basics of postmortem CT technique are discussed here as well as advanced techniques in scanning and post-processing.

Korean radiographers' awareness, experiences, and education needs in forensic medicine and forensic radiology

This study assesses the need for education in forensic medicine and forensic radiology among radiographers by investigating the perceptions and experiences of Korean radiographers working in medical institutions. A structured questionnaire was administered to participants, collected, and analyzed. The results showed that despite receiving frequent forensic cases, Korean radiographers face difficulties in taking appropriate measures about forensic radiology due to a lack of awareness and knowledge of its forensic aspects. The participants indicated that university education in forensic medicine and forensic radiology is necessary. Therefore, it is imperative to develop and implement policies for forensic education programs to enhance radiographers' forensic knowledge and capabilities. Universities should conduct courses on forensic radiology and provide continuing education for radiographers working in this field.

Optimization of Postprocessing parameters for abdominal Forensic CT scans

Aim

Postmortem Computed Tomography (PMCT) is gradually introduced at forensic institutes. Image reconstruction software can increase diagnostic potential in CT by increasing distinction between structures and reduction of artifacts. The aim of this study was to develop and evaluate novel image reconstruction parameters for postmortem conditions, to increase image quality and diagnostic potential of CT scans.

Method

Twenty PMCT scans of deceased hereof two in severe decay were subjected to four reconstruction techniques: a standard reconstruction algorithm, the detail reconstruction algorithm and two novel algorithms based on the standard algorithm, but with different Hounsfield settings. Image quality was evaluated by visual grading analysis (VGA) by four forensic radiologist observers.

Results

The VGA did not prove that any of the reconstruction techniques were superior to the others. For standard and detail, the two pre-defined reconstruction algorithms, VGA scores were indiscernible and were superior to the equally indiscernible Hounsfield reconstructions on parameters translated into Sharpness and Low Contrast Resolution. The two alternative Hounsfield settings were superior with respect to Noise and Artifacts/Beam Hardening.

Conclusion

The study elucidates the possiblity for multiple reconstructions specialized for PMCT conditions, to accommodate the special conditions when working with the deceased. Despite the lack of clear improvements in the tested reconstructions, this study provides an insight into some of the possibilities of improving PMCT quality using reconstruction techniques.

[Features of detection and interpretation of intravital and postmortem changes according to the results of traditional X-ray and X-ray computed tomography of objects from historical graves and artefacts]

OBJECTIVE

To study emergence mechanism, physical nature, pattern of intravital and postmortem changes of biological and non-biological objects originated in the period from 1550 to 1918 yr. using traditional X-ray and X-ray computed tomography.

MATERIAL AND METHODS

The relics of Saint Macarius the Roman of Novgorod, the remains of the First Reverend of the Resurrection Novodevichy Convent in Saint Petersburg Mother Superior Theophania, damages on the chair leg on which Tsesarevich Alexey sat during the shooting of Russian Emperor Nicholas II, his family and entourage in 1918 in Yekaterinburg were stidued.

RESULTS AND CONCLUSION

The application of highly informative methods of traditional X-ray and X-ray computed tomography of biological and non-biological objects showed their high informativity and allowed to correctly interpret the emergence mechanism, physical nature, pattern of intravital and postmortem changes of skeleton bones and historical artefact (chair legs) originated long ago. The necessity of special professional training and advanced training of experts in forensic radiology to prevent possible diagnostic and expert errors has been substantiated.

Technical note: Interest of focused fields in post-mortem computed tomography using photorealistic images for age at death estimation from the pubic symphysis

INTRODUCTION

The morphological assessment of the pubic symphysis using the Suchey-Brooks method is considered a reliable age at death indicator. Age at death estimation methods can be adapted to the images obtained from post-mortem computed tomography (PMCT). The aim of this study is to evaluate the utility of pubic symphysis photorealistic images obtained through Global illumination rendering (GIR) for age at death estimation from whole-body PMCT and from focused PMCT on the pubic bone.

MATERIALS AND METHODS

We performed virtual age at death estimation using the Suchey Brooks method from both the whole-body field of view (Large Field of View: LFOV) and the pubis-focused field of view (Small and Field of View: SFOV) of 100 PMCT. The 3D photorealistic images were evaluated by three forensic anthropologists and the results were statistically evaluated for accuracy of the two applied PMCT methods and the intra- and inter-observer errors.

RESULTS

When comparing the two acquisitions of PMCT, the accuracy rate reaches 98.5% when using a pubic-focused window (SFOV) compared to 86% with a whole-body window (LFOV). Additionally, the intra- and inter-observer variability has demonstrated that the focused window provides better repeatability and reproducibility.

CONCLUSION

Adding a pubic-focused field of view to standard PMCT and processing it with GIR appears to be an applicable technique that increases the accuracy rate for age at death estimation from the pubic symphysis.

Added value of ultra-short echo time and fast field echo using restricted echo-spacing MR imaging in the assessment of the osseous cervical spine

PURPOSE

To evaluate the added value of ultra-short echo time (UTE) and fast field echo resembling a CT using restricted echo-spacing (FRACTURE) MR sequences in the assessment of the osseous cervical spine using CT as reference.

MATERIALS AND METHODS

Twenty-seven subjects underwent postmortem CT and MRI within 48 h. Datasets were anonymized and analyzed retrospectively by two radiologists. Morphological cervical spine alterations were rated on CT, UTE and FRACTURE images. Afterward, neural foraminal stenosis was graded on standard MR and again after viewing additional UTE/FRACTURE sequences. To evaluate interreader and intermodality reliability, intra-class correlation coefficients (ICC) and for stenosis grading Wilcoxon-matched-pairs testing with multiple comparison correction were calculated.

RESULTS

Moderate interreader reliability (ICC = 0.48-0.71) was observed concerning morphological findings on all modalities. Intermodality reliability was good between modalities regarding degenerative vertebral and joint alterations (ICC = 0.69-0.91). Compared to CT neural stenosis grades were more often considered as nonsignificant on all analyzed MR sequences. Neural stenosis grading scores differed also significantly between specific bone imaging sequences, UTE and FRACTURE, to standard MR sequences. However, no significant difference was observed between UTE and FRACTURE sequences.

CONCLUSION

Compared to CT as reference, UTE or FRACTURE sequence added to standard MR sequences can deliver comparable information on osseous cervical spine status. Both led to changes in clinically significant stenosis gradings when added to standard MR, mainly reducing the severity of neural foramina stenosis.

Perimortem Skeletal Sharp Force Trauma: Detection Reliability on CT Data, Demographics and Anatomical Patterns from a Forensic Dataset

Simple Summary

The increased use of computed tomography images in forensic anthropology is easily explained with a variety of benefits: among other reasons they are digitally stored, they can easily be shared and they are non-invasive. However, it is not clear how suitable these images are for forensic anthropologists to detect sharp force trauma. Therefore, we analyzed computed tomography images, by observing digital images of 41 forensic cases in different viewing modalities. In addition, we looked for anatomical injury patterns in the soft- and hard-tissues and any significant correlations between the manner of death (suicide or homicide) with different parameters. Our findings indicated a superiority of viewing the images in 2D, but not all bone lesions were detected. The manner of death was significantly correlated to some of the parameters, which could be extrapolated to future forensic anthropological cases. We promote the inclusion of imaging training into the anthropological curricula.

Abstract

The increasing importance of trauma analysis by means of postmortem computed tomography (PMCT) is insufficiently reflected in forensic curricula, nor are best practice manuals available. We attempt to detect sharp force bone lesions on PMCT of closed forensic cases with the aims of assessing errors and pointing out patterns in anatomical location and manner of death (MOD). We investigated 41 closed sharp force fatality cases, with available PMCT and forensic reports. Two observers with different radiological training assessed the lesions on PMCT scans (2D and 3D) for comparison with the reports. Between 3% (suicides) and 15.3% (homicides) of sharp force injuries caused visible bone lesions. While our observations were repeatable, each forensic investigation left a similar number of bone lesions undetected. Injury patterns differed between MOD, with thoracic bone lesions being most frequent overall. Soft tissue injury location varied between the MOD. Associations between MOD and age as well as number of injuries were significant. The detection of bone lesions on PMCT for untrained forensic specialists is challenging, curricula and pertinent manuals are desirable. With the low frequency of bone lesions compared to soft tissue injuries, we should be aware when analyzing decomposed bodies.

Sensitivity and specificity of post-mortem computed tomography in skull fracture detection-a systematic review and meta-analysis

Post-mortem computed tomography (PMCT) has been increasingly used as routine examination in forensic pathology. No recent review of the growing number of papers on the ability of PMCT to detect skull fracture exists, and original papers report sensitivities from 0.85 to 1.00. This systematic review (PROSPERO: CRD42021233264) aims to provide a meta-analysis of sensitivity and specificity of PMCT in skull fracture detection. We searched PubMed, MEDLINE and Embase for papers published between January 2000 and August 2021 reporting raw numbers, sensitivity and specificity or Abbreviated Injury Score for PMCT compared to autopsy. Papers without both PMCT and autopsy, no separate reporting of the neuro-cranium, exclusively on children, sharp trauma, gunshot or natural death as well as case reports and reviews were excluded. Two authors independently performed inclusion, bias assessment and data extraction. QUADAS-2 was used for bias assessment and a random effects models used for meta-analysis. From 4.284 hits, 18 studies were eligible and 13 included in the meta-analysis for a total of 1538 cases. All deceased were scanned on multi-slice scanners with comparable parameters. Images were evaluated by radiologists or pathologists. Intra- and inter-observer analyses were rarely reported. In summary, sensitivity of PMCT for detection of fractures in the skull base was 0.87 [0.80; 0.92] with specificity 0.96 [0.90; 0.98], and sensitivity for the vault was 0.89 [0.80; 0.94] with specificity 0.96 [0.91; 0.98]. The mixed samples are a limitation of the review.

Forensic imaging: a powerful tool in modern forensic investigation

Forensic imaging is a non-invasive examination process during the forensic investigation. It is mainly used in forensic pathology as an adjunct to the traditional autopsy. In the past two decades, forensic imaging has been vigorously developed by forensic experts from computed tomography (CT) to multiple augmented techniques through CT and magnetic resonance imaging (MRI). The application field of forensic imaging has also been broadened as its advantages are recognised by more forensic practitioners. In addition to the forensic pathology, this technique has been used in other forensic disciplines, including forensic anthropology, forensic odontology, forensic ballistics and wildlife forensics, etc. This article reviews the development of forensic imaging as the practice and research development in different forensic disciplines based on the relevant literature analysis.

Potentials of post-mortem CT investigations during SARS-COV-2 pandemic: a narrative review

In December 2019, a new coronavirus, SARS-COV-2, caused a cluster of cases of pneumonia in China, and rapidly spread across the globe. It was declared a pandemic by the World Health Organization on March 11th, 2020. Virtual autopsy by post-mortem CT (PMCT) and its ancillary techniques are currently applied in post-mortem examinations as minimally or non-invasive techniques with promising results. In this narrative review, we speculate on the potentials of PMCT and its ancillary techniques, as a viable investigation technique for analysis of suspected or confirmed SARS-COV-2 deaths. An online literature search was performed by using three prefix search terms (postmortem, post-mortem, post mortem) individually combined with the suffix radiology, imaging, computed tomography, CT and with the search terms ‘SARS-CoV-2’ and ‘COVID-19’ to identify papers about PMCT and its ancillary techniques in SARS-COV-2 positive cadavers. PMCT findings suggestive for pulmonary COVID-19 in deceased positive SARS-COV-2 infection are reported in the literature. PMCT ancillary techniques were never applied in such cases. PMCT imaging of the lungs has been proposed as a pre-autopsy screening method for SARS-COV-2 infection. Further studies are needed to ascertain the value of PMCT in determining COVID-19 as the cause of death without autopsy histopathological confirmation. We advocate the application of PMCT techniques in the study of ascertained or suspected SARS-COV-2 infected deceased individuals as a screening technique and as a method of post-mortem investigation, to augment the numbers of case examined and significantly reducing infection risk for the operators.

Fractures of the neuro-cranium: sensitivity and specificity of post-mortem computed tomography compared with autopsy

Post-mortem computed tomography (PMCT) is a routine tool in many forensic pathology departments as it is fast and non-destructive and allows less gruesome visualization than photographs, and the images are indefinitely storable. Several studies investigated congruence between PMCT and autopsy for skull fracture but registered only the presence or absence of fracture systems. The objective of this study was to determine location-specific sensitivity and specificity of PMCT for individual fracture lines in blunt force head trauma. Accurate 3D models based on PMCT data with all fracture lines visible are important for future studies on fractures, applying finite element analysis (FEA). We retrospectively sampled adult cases from 2013 to 2019 with skull fracture mentioned in the autopsy report. PMCT was on a Siemens 64-slice scanner and autopsy according to international guidelines. The location and direction of all fracture lines at autopsy and at de novo interpretation of scans were registered and compared. Ninety-nine cases with 4809 individual findings were included. Age ranged from 18 to 100 years. The overall sensitivity was 0.58, and specificity was 0.91. For individual locations, sensitivity ranged from 0.24 to 0.85, and specificity ranged from 0.73 to 1.00. Intra-observer agreement was 0.74, and inter-observer agreement ranged from 0.43 to 0.58. In conclusion, PMCT is suited for detection of fracture systems, but not for detection of all individual fracture lines. Our results differed from the existing literature due to the methodological choices of registering individual fracture lines. Future studies utilising FEA must supplement PMCT with autopsy data.

Age-related changes in the hyoid bone: An autopsy-based radiological analysis

Forensic age estimation is a crucial aspect of the biological profile of unidentified cadavers. The utility of age-related changes of hyoid bone fusion in forensic age estimation has not been explored much in the past. These age-related changes can be visualised in both the living and the dead using conventional radiography. These changes can assist medico-legal professionals and forensic anthropologists in the identification of unknown deceased, especially when the cadaver is mutilated or charred or when the other well-established indicators of skeletal and dental maturity are absent. The aims of this study were to evaluate age-related changes in the hyoid bone and to ascertain whether these changes may be utilised for age estimation in forensic examinations. The hyoid bone was carefully dissected using a standard procedure from 75 cadavers during post-mortem examination. The hyoid bone was radiographed, and the bone was replaced in the body cavity before the post-mortem examination was completed. Hyoid bone fusion was studied by using a standard grading method. Spearman's correlation coefficient was calculated between the fusion scores and chronological age to assess their relationship. Box and whisker plots of fusion stage-wise age distribution were constructed to demonstrate the gradual linear relationship between hyoid bone fusion and the chronological age of the study participants. The present study concludes that hyoid bone fusion is an indicator of the chronological age of an individual and can be used in conjunction with other methods of age estimation such as the skeletal and dental age.

Annular distribution patterns of .357 Magnum fragments in soft tissue simulants after striking hard material that prevented the bullet from exiting

The distribution of bullet fragments inside the body can provide information for the reconstruction of events in shooting incidents. The formation of an annular distribution pattern of bullet fragments was recently presented in a case report. The fragments were scattered radially around an exit-re-entrance wound resulting from collision of the bullet with a floor tile immediately after perforating the body. Such an annular distribution pattern of bullet fragments around an exit-re-entrance wound would indicate that a body was in close contact with hard material, for instance, lying on hard ground or leaning against a concrete wall, when the shot was fired. The aim of this experimental study was to investigate the formation and reproducibility of the annular distribution pattern of bullet fragments. It was assumed that the distribution pattern would be formed when hard material blocks a bullet from exiting a soft tissue simulant. Furthermore, the dependency of this distribution pattern on the impact angle was assessed. For this purpose, .357 Magnum bullets were fired at ballistic soap blocks with a steel plate at the rear end of the soap block. Six shots were performed at an impact angle of 90° (experiment 1), and six shots were performed at an impact angle of 45° (experiment 2). The distribution pattern of the fragments inside the individual soap blocks was examined via computed tomography (CT). In experiment 1, the bullets burst, and large fragments formed annular distribution patterns with a radial extent of approximately 4.9 cm and a maximum depth of approximately 2.3 cm. In experiment 2, the bullets ricocheted from the steel plate, and tiny fragments formed small annular distribution patterns at the points of ricochet with a radial extent of approximately 1.5 cm and a maximum depth of approximately 1.2 cm. The end position of the large main fragments was approximately 9.7 cm distant from the point of ricochet at a mean depth of 2.7 cm. The mean kinetic energy of the bullets at the time of impact was 580 J in experiment 1 and 394 J in experiment 2. Distribution patterns of bullet fragments in the body may provide information not only on the impact angle of a bullet but also on whether the body was in contact with a hard material that blocked the bullet from exiting the body. CT proved to be an appropriate imaging method for such investigations.

Evaluation of ultrashort echo-time (UTE) and fast-field-echo (FRACTURE) sequences for skull bone visualization and fracture detection - A postmortem study

BACKGROUND AND PURPOSE

CT is considered the modality of choice in the assessment of the skull due to the fast and accurate depiction of bone structures. Nevertheless, MRI has evolved into a possible alternative due to optimal soft tissue contrast and recent advances with the ability to visualize tissues with shortest T2 times, such as osseous structures. In this study we compare skull bone visualization and fracture detection across two MRI sequences to CT as reference standard.

MATERIAL AND METHODS

Twenty subjects underwent CT and MRI with less than 72 h between examination. The MRI protocol included a 2D ultrashort echo time (UTE) and a 3D multi-echo in-phase fast-field-echo (FRACTURE) sequence. Independent raters evaluated qualitative characteristics and fracture detectability in different skull subregions (skull vault, skull base and viscerocranium). Interrater and intermodality agreement was evaluated by calculating intraclass coefficients (ICC).

RESULTS

FRACTURE ICC indicated a good agreement in all subregions (ICC = 0.83 - 0.88), whereas UTE had excellent results calculated in the skull vault and viscerocranium (ICC = 0.91 - 0.94). At the skull vault, both MRI sequences received an overall good rating (UTE: 2.63 ± 0.42 FRACTURE. 2.81 ± 0.32). Fracture detection using MRI sequences for the skull vault, was highest compared to other subregions.

CONCLUSIONS

Both MRI sequences may provide an alternative e.g. for surgical planning or follow up exams of the osseous neurocranium; although, at the skull base and viscerocranium bone visualization with MRI bone imaging sequences perform inferior to CT standard imaging.

CT-based and morphological comparison of glenoid inclination and version angles and mineralisation distribution in human body donors

Background

For optimal prosthetic anchoring in omarthritis surgery, a differentiated knowledge on the mineralisation distribution of the glenoid is important. However, database on the mineralisation of diseased joints and potential relations with glenoid angles is limited.

Methods

Shoulder specimens from ten female and nine male body donors with an average age of 81.5 years were investigated. Using 3D-CT-multiplanar reconstruction, glenoid inclination and retroversion angles were measured, and osteoarthritis signs graded. Computed Tomography-Osteoabsorptiometry (CT-OAM) is an established method to determine the subchondral bone plate mineralisation, which has been demonstrated to serve as marker for the long-term loading history of joints. Based on mineralisation distribution mappings of healthy shoulder specimens, physiological and different CT-OAM patterns were compared with glenoid angles.

Results

Osteoarthritis grades were 0-I in 52.6% of the 3D-CT-scans, grades II-III in 34.3%, and grade IV in 13.2%, with in females twice as frequently (45%) higher grades (III, IV) than in males (22%, III). The average inclination angle was 8.4°. In glenoids with inclination ≤10°, mineralisation was predominantly centrally distributed and tended to shift more cranially when the inclination raised to > 10°. The average retroversion angle was − 5.2°. A dorsally enhanced mineralisation distribution was found in glenoids with versions from − 15.9° to + 1.7°. A predominantly centrally distributed mineralisation was accompanied by a narrower range of retroversion angles between − 10° to − 0.4°.

Conclusions

This study is one of the first to combine CT-based analyses of glenoid angles and mineralisation distribution in an elderly population. The data set is limited to 19 individuals, however, indicates that superior inclination between 0° and 10°-15°, and dorsal version ranging between − 9° to − 3° may be predominantly associated with anterior and central mineralisation patterns previously classified as physiological for the shoulder joint. The current basic research findings may serve as basic data set for future studies addressing the glenoid geometry for treatment planning in omarthritis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04660-4.

Technical and interpretive pitfalls of postmortem CT: Five examples of errors revealed by autopsy

Image acquisition of dead bodies, particularly using postmortem computed tomography (PMCT), has become common in forensic investigations worldwide. Meanwhile, in countries such as Japan which have an extremely low rate of autopsy, PMCT is being increasingly used in the clinical field to certify the cause of death (COD) without performing an autopsy or toxicological tests, even in cases of unnatural death. Additionally, these PMCT images are predominantly interpreted by clinical personnel such as emergency physicians or clinicians who are not trained in PMCT interpretation and who work for the police, that is, the so-called police doctors. Many potential pitfalls associated with the use of PMCT have been previously described in textbooks and published papers, including the pitfalls of not performing a complete forensic pathology investigation, and the use of physicians without appropriate PMCT training to interpret PMCT and direct death investigation and certification. We describe five examples in which apparent misdiagnosis of COD based on PMCT misinterpretation was revealed by autopsy. Here are the five examples of errors: (1) Postmortem changes were misinterpreted as COD, (2) resuscitation effects were misinterpreted as COD, (3) COD was determined after an incomplete examination, (4) fatal findings caused by external origin were wrongly interpreted as 'of internal origin' based on PMCT, and (5) non-fatal findings on PMCT were wrongly interpreted as fatal. Interpretation of PMCT by appropriately trained physicians and an accompanying complete forensic investigation, including autopsy when indicated, is necessary to prevent significant errors in COD determination and related potential adverse medicolegal consequences.

Cinematic rendering of a burst sagittal suture caused by an occipito-frontal gunshot wound

The computed tomography (CT) scan of a 19-year-old man who died from an occipito-frontal gunshot wound presented an impressive radiating fracture line where the entire sagittal suture burst due to the high intracranial pressure that arose from a near-contact shot from a 9 mm bullet fired from a Glock 17 pistol. Photorealistic depictions of the radiating fracture lines along the cranial bones were created using three-dimensional reconstruction methods, such as the novel cinematic rendering technique that simulates the propagation and interaction of light when it passes through volumetric data. Since the brain had collapsed, depiction of soft tissue was insufficient on CT images. An additional magnetic resonance imaging (MRI) examination was performed, which enabled the diagnostic assessment of cerebral injuries.

Threshold-dependent iodine imaging and spectral separation in a whole-body photon-counting CT system

OBJECTIVE

To evaluate the dual-energy (DE) performance and spectral separation with respect to iodine imaging in a photon-counting CT (PCCT) and compare it to dual-source CT (DSCT) DE imaging.

METHODS

A semi-anthropomorphic phantom extendable with fat rings equipped with iodine vials is measured in an experimental PCCT. The system comprises a PC detector with two energy bins (20 keV, T) and (T, eU) with threshold T and tube voltage U. Measurements using the PCCT are performed at all available tube voltages (80 to 140 kV) and threshold settings (50-90 keV). Further measurements are performed using a conventional energy-integrating DSCT. Spectral separation is quantified as the relative contrast media ratio R between the energy bins and low/high images. Image noise and dose-normalized contrast-to-noise ratio (CNRD) are evaluated in resulting iodine images. All results are validated in a post-mortem angiography study.

RESULTS

R of the PC detector varies between 1.2 and 2.6 and increases with higher thresholds and higher tube voltage. Reference R of the EI DSCT is found as 2.20 on average overall phantoms. Maximum CNRD in iodine images is found for T = 60/65/70/70 keV for 80/100/120/140 kV. The highest CNRD of the PCCT is obtained using 140 kV and is decreasing with decreasing tube voltage. All results could be confirmed in the post-mortem angiography study.

CONCLUSION

Intrinsically acquired DE data are able to provide iodine images similar to conventional DSCT. However, PCCT thresholds should be chosen with respect to tube voltage to maximize image quality in retrospectively derived image sets.

KEY POINTS

• Photon-counting CT allows for the computation of iodine images with similar quality compared to conventional dual-source dual-energy CT. • Thresholds should be chosen as a function of the tube voltage to maximize iodine contrast-to-noise ratio in derived image sets. • Image quality of retrospectively computed image sets can be maximized using optimized threshold settings.

7-T MRI for brain virtual autopsy: a proof of concept in comparison to 3-T MRI and CT

The detection and assessment of cerebral lesions and traumatic brain injuries are of particular interest in forensic investigations in order to differentiate between natural and traumatic deaths and to reconstruct the course of events in case of traumatic deaths. For this purpose, computed tomography (CT) and magnetic resonance imaging (MRI) are applied to supplement autopsy (traumatic death) or to supplant autopsy (natural deaths). This approach is termed “virtual autopsy.” The value of this approach increases as more microlesions and traumatic brain injuries are detected and assessed. Focusing on these findings, this article describes the examination of two decedents using CT, 3-T, and 7-T MRI. The main question asked was whether there is a benefit in using 7-T over 3-T MRI. To answer this question, the 3-T and 7-T images were graded regarding the detectability and the assessability of coup/contrecoup injuries and microlesions using 3-point Likert scales. While CT missed these findings, they were detectable on 3-T and 7-T MRI. However, the 3-T images appeared blurry in direct comparison with the 7-T images; thus, the detectability and assessability of small findings were hampered on 3-T MRI. The potential benefit of 7-T over 3-T MRI is discussed.

Postmortem CT and autopsy findings in nine victims of terrorist attack

In a foreign country, a religious terrorist group raided a restaurant, using pipe bombs, sharp-edged weapons, and various types of firearms (handguns, submachine guns, and AK-47 assault rifles) loaded with normal and prohibited bullets to kill foreigner customers, some of whom were Italian tourists. Local pathologists performed forensic autopsies on the bodies, but we were asked to perform additional external examinations, postmortem computed tomography (PMCT) scans, and then a second round of complete autopsies on nine victims (5 females and 4 males). Four victims had slash wounds inflicted by sharp-edged weapons, mostly localized in the head and neck. All but two victims had gunshot wounds. Finally, three casualties had injuries caused by the explosion of improvised explosive devices. In all cases, PMCT was a reliable source of information and provided strategic guide during autopsies, helping identify and describe the injuries and thus reconstruct the events. Therefore, in these cases, we suggest integrating the autopsy findings with the postmortem radiological data.

Postmortem Computed Tomography and Magnetic Resonance Imaging of an Abdominal Gunshot Wound

The use of postmortem computed tomography (CT) has been described in many articles concerning gunshot injuries. Postmortem magnetic resonance imaging (MRI) for better assessment of soft tissue injuries has also been mentioned in the literature, albeit much less often. The use of postmortem MRI for abdominal gunshot wounds has not been previously presented in the literature. The present case report describes the findings of an abdominal gunshot wound detected by postmortem CT and MRI, followed by an autopsy. The main imaging findings on CT were a hyperdense ring at the entrance wound, which indicated the muzzle imprint mark, a hyperdense region beneath the skin, which was suggestive of combustion residue, gas cavities surrounding the bullet path, which might be related to the temporary cavity, and a fracture of the 13th rib on the left. Magnetic resonance imaging provided a clear depiction of defects in the muscle tissue and peritoneal fat, as well as an injury to the left kidney and a large volume of blood in the abdominal cavity. Computed tomography combined with MRI provided a descriptive presentation of the intracorporeal trajectory noninvasively. Autopsy confirmed the radiologic findings but additionally revealed further relevant findings, which were not detected radiologically, such as a duodenal perforation. Autopsy also detected subendocardial hemorrhages and shock kidney, which were consistent with severe blood loss.The imaging findings and their interpretations are discussed in this case report, as well as the role of CT and MRI in the assessment of abdominal gunshot wounds compared with autopsy.

Comparison of MR Ultrashort Echo Time and Optimized 3D-Multiecho In-Phase Sequence to Computed Tomography for Assessment of the Osseous Craniocervical Junction

BACKGROUND

To assess changes of the craniocervical junction (CCJ), computed tomography (CT) is considered the reference standard. Recent advances in bone depiction on magnetic resonance imaging (MRI) enable high-quality visualization of osseous structures. Consequently, MRI may serve as an alternative to CT, without the use of ionizing radiation.

PURPOSE

To compare two MRI sequences optimized for bone visualization to the CT reference standard in the assessment of the osseous CCJ.

STUDY TYPE

Prospective.

POPULATION/SUBJECTS

Twenty-seven decedents and five healthy volunteers.

FIELD STRENGTH/SEQUENCE

3T/ultrashort-echo time gradient echo (UTE) and optimized 3D-multiecho in-phase gradient echo sequences (FRACTURE).

ASSESSMENT

All decedents were scanned with both MRI sequences and CT. Three observers rated degeneration to obtain a score for the upper (atlanto-dental and left/right atlanto-occipital joint) and for the lower part of the CCJ (left and right atlanto-axial joint). Two reader rated the following quantitative parameters: basion-axial-interval, atlanto-dental-interval, atlanto-occipital-interval, Powers-ratio, and signal/contrast-to-noise-ratio. As a proof of concept, five healthy volunteers were scanned with both MRI sequences.

STATISTICAL TESTS

Degeneration was assessed on a Likert scale by three independent observers. Interrater and intermodality reliability were calculated using an intraclass correlation coefficient. To compare distance measurements between examination methods, a Friedman test, between-degenerative ratings, and a Kruskal-Wallis test were performed.

RESULTS

Degenerative ratings of the CCJ between MRI sequences and CT showed a good interrater and intermodality agreement. MRI sequences tended to underestimate the degree of degeneration compared to CT, and this became more marked with increasing degeneration severity. There were no significant relationships between distance measurements and the degree of degeneration (P_CT = 0.62, P_UTE = 0.64, P_FRACTURE = 0.67). The in vivo examination proved the feasibility of both MRI methods in a clinical setting.

DATA CONCLUSION

Quantitative and qualitative ratings on MR images were comparable to CT images; thus, MRI may be a valid alternative to CT assessing the CCJ.

LEVEL OF EVIDENCE

1.

TECHNICAL EFFICACY STAGE

3.

CT and MRI of a transcardiac gunshot wound with an annular distribution of bullet fragments surrounding an exit-re-entrance wound after the bullet burst from a floor tile upon exiting the lying body

This case report describes medicolegal examinations of a decedent with a fatal gunshot wound. The decedent lied on the floor as a bullet was fired into his chest. Computed tomography (CT) and magnetic resonance imaging (MRI) were performed as part of the judicial investigation. The MRI examination was valuable for delineating the wound channel through the left ventricle, which was deemed the main cause for internal bleeding and fatal blood loss. The diagnostic value of CT for the detection of injuries was low in this case. However, CT allowed for the virtual investigation of bullet fragments. According to CT-based dual-energy index calculations, it could be inferred that the fragments were most likely made of lead matching .357 Magnum R-P cartridges that were found at the scene. The bullet fragments were located underneath the skin at the suspected exit wound. The exit wound was actually an exit-re-entrance wound, as it can be assumed that the fragments re-entered the body after the bullet burst from hard ground upon exiting the body of the decedent, who was lying on the floor. CT visualized an uncommon annular distribution pattern for the bullet fragments surrounding the exit-re-entrance wound. The formation of such an annular distribution pattern of bullet fragments and the relevant conclusions that may be drawn from such a distribution pattern are discussed in this article.

Can post-mortem coronary artery calcium scores aid diagnosis in young sudden death?

This study sought to explore the feasibility and utility of post-mortem coronary artery calcium (CAC) scoring in identifying patients with ischemic heart disease as cause of sudden death. 100 deceased patients aged 18-50 years underwent post-mortem examination in the setting of sudden death. At post-mortem, fifty cases were determined to have ischemic heart disease, and fifty had death attributed to trauma or unascertained causes. The CAC score was calculated in a blinded manner from post-mortem CTs performed on all cases. CAC scores were assessable in 97 non-decomposed cases (feasibility 97%). The median CAC score was 88 Agatston units [IQR 0-286] in patients deceased from ischemic heart disease vs 0 [IQR 0-0] in patients deceased from other causes (p < 0.0001). Presence of any coronary calcification differed significantly between ischemic heart disease and non-ischemic groups (adjusted odds ratio 10.7, 95% CI 3.2-35.5). All cases with a CAC score > 100 (n = 22) had ischemic heart disease as the cause of death. Fifteen cases had a CAC score of zero but severe coronary disease at post-mortem examination. Post-mortem CAC scoring is highly feasible. An elevated CAC score in cases 18-50 years old with sudden death predicts ischemic heart disease at post-mortem examination. However, a CAC score of zero does not exclude significant coronary artery disease. Post-mortem CAC score may be considered as a further assessment tool to help predict likely cause of death when there is an objection to or unavailability of post-mortem examination.

Feasibility, technique and accuracy of ultrasound-guided transurethral injections into the urinary sphincter of female cadavers: proof of concept

BACKGROUND

The injection of muscle precursor cells (MPC) into the external urinary sphincter muscle (EUS) is a promising therapeutic option for regenerative treatment of stress urinary incontinence (SUI). The objective of the present project was to conduct a pre-clinical trial to investigate the feasibility and accuracy of ultrasound (US) guided, transurethral injections into the EUS of female cadavers.

METHODS

This is a prospective, anatomical, interventional and radiological cadaveric laboratory investigation. Two urologists performed transurethral US-guided injections to deliver nano-iron particles into the EUS. The intervention was performed in three unfixed, fresh female cadavers. Each cadaver received MRI before and CT as well as MRI of the pelvis after the injections.

RESULTS

The precision and accumulation of nano-iron particles in the EUS was compared using a rating scale to evaluate left versus right and anterior versus posterior distribution in axial and sagittal orientation with US, MRI and CT. The accuracy of our US-guided injections into the anterior target region yielded 4 points on the rating scale. Adequate precision and accumulation of particles in the left versus right EUS were also demonstrated (3 vs. 3.33 points, respectively). Signal intensity in MRI revealed a mean ratio of 0.33 before and after injection. CT scans showed no relevant artefacts impairing the assessment.

CONCLUSION

US-guided, transurethral injection into the EUS is feasible and imaging reveals a precise accumulation in the target region. Our method provides an appropriate approach to deliver MPC in the EUS muscle for a regenerative treatment of SUI in the near future.

Virtopsy of a gravid Boa constrictor using computed tomography and magnetic resonance imaging

This article presents radiologic examinations of a deeply sedated Boa constrictor with boid inclusion body disease (BIBD) as an adjunction to the subsequent necropsy. This method is known as virtopsy. The Boa constrictor in the present case was gravid. Computed tomography (CT) allowed for the detailed depiction of a fetal skeleton at the rear end of the adult snake. Furthermore, tiny gas formation was detected inside the cranium of the fetus, which was deemed a radiologic sign for decomposition. Magnetic resonance imaging (MRI) delineated the soft tissue at high resolution. This article illustrates the use of CT and MRI for the examination of a gravid Boa constrictor before necropsy and demonstrates the detection of "normal" postmortem findings leading to the confirmation of fetal death in situ.

Noninvasive 7 tesla MRI of fatal craniocerebral gunshots - a glance into the future of radiologic wound ballistics

Compared to computed tomography (CT), magnetic resonance imaging (MRI) provides superior visualization of the soft tissue. Recently, the first 7 Tesla (7 T) MRI scanner was approved for clinical use, which will facilitate access to these ultra-high-field MRI scanners for noninvasive examinations and scientific studies on decedents. 7 T MRI has the potential to provide a higher signal-to-noise ratio (SNR), a characteristic that can be directly exploited to improve image quality and invest in attempts to increase resolution. Therefore, evaluating the diagnostic potential of 7 T MRI for forensic purposes, such as assessments of fatal gunshot wounds, was deemed essential. In this article, we present radiologic findings obtained for craniocerebral gunshot wounds in three decedents. The decedents were submitted to MRI examinations using a 7 T MRI scanner that has been approved for clinical use and a clinical 3 T MRI scanner for comparison. We focused on detecting tiny injuries beyond the wound tract caused by temporary cavitation, such as microbleeds. Additionally, 7 T T₂-weighted MRI highlighted a dark (hypo intense) zone beyond the permanent wound tract, which was attributed to increased amounts of paramagnetic blood components in damaged tissue. Microbleeds were also detected adjacent to the wound tract in the white matter on 7 T MRI. Based on the findings of radiologic assessments, the advantages and disadvantages of postmortem 7 T MRI compared to 3 T MRI are discussed with regard to investigations of craniocerebral gunshot wounds as well as the potential role of 7 T MRI in the future of forensic science.

Heavy metal in radiology: how to reliably differentiate between lodged copper and lead bullets using CT numbers

BACKGROUND

The in situ classification of bullets is of interest in forensic investigations when the bullet cannot be removed. Although computed tomography (CT) is usually performed on shooting victims, visual assessment, or caliber measurements using CT can be challenging or infeasible if the bullets are deformed or fragmented. Independent from the bullet's intactness, x-ray attenuation values (CT numbers) may provide information regarding the material of the bullet.

METHODS

Ethical approval was not required (animal cadavers) or waived by the ethics committee (decedents). Copper and lead bullets were fired into animal cadavers, which then underwent CT scanning at four energy levels (80, 100, 120, and 140 kVp). CT numbers were measured within regions of interest (ROIs). In addition to comparing CT numbers, the dual-energy index (DEI), representing the ratio between the CT numbers of two energy levels, was calculated. The most appropriate method was applied for decedents with fatal gunshot wounds.

RESULTS

CT numbers demonstrated no significant difference between copper and lead bullets, and false classifications can easily occur. DEI calculations revealed significant differences between the two groups of bullets. The 120/140 DEIs calculated from the maximum CT numbers obtained from ROIs at the edge of copper versus lead bullets presented a significant difference (p = 0.002) and a gap between the CT numbers of copper and lead bullets and was successfully applied for the decedents.

CONCLUSIONS

This study presents a viable method for distinguishing copper and lead bullets in situ via CT and highlights the potential pitfalls of incorrect classifications.

In situ identification of Action 4, SECA and QD-PEP bullets from special police ammunitions by computed tomography

INTRODUCTION

Special deformation bullets were developed for police forces to achieve a defined penetration depth (avoiding over-penetration) and a controlled energy transfer (avoiding collateral damage). This article focuses on Action 4, SECA and QD-PEP bullets. These 9 mm bullets were specially designed for controlled deformation. The characteristic slight mushrooming with a front cross-section of approximately 11.5 mm after entering a ballistic simulant was verified in ballistic tests. To achieve such slight mushrooming, the projectile's core is hollowed. The purpose of this study was to investigate the feasibility of visualising the hollowed cores of Action 4, SECA and QD-PEP bullets using a standard clinical computed tomography (CT) scanner for non-invasive identification of these special bullets from police ammunitions.

METHODS

First, undeformed specimens were scanned to reveal the shape of the hollowed core of each type of special bullet. Second, Action 4, SECA and QD-PEP bullets were fired towards animal cadaver models to visualise their hollow core after deformation inside biological tissue. Third, two reviewers were tasked with identifying special bullets from police ammunition (Action 4 bullets: n = 3) among 10 CT examinations of humans with lodged projectiles who were selected by the supervisor of the study.

RESULTS

The CT scans of the undeformed specimens revealed the special design of the bullets' metal core. All special bullets from police ammunitions that were fired towards an animal cadaver model demonstrated the characteristic slight mushrooming. In accordance with the CT scans of the undeformed bullets, visualisation of the individual internal cavities of the special bullets allowed the Action 4, SECA and QD-PEP bullets to be clearly distinguished. With regard to the real forensic cases, both reviewers clearly identified each of the three Action 4 bullets among all other lodged projectiles.

CONCLUSIONS

This study demonstrates the feasibility of identifying Action 4, SECA and QD-PEP bullets from special police ammunitions by CT. The individual shapes of the cavity inside the bullets were clearly visible on CT. In situ identification of these bullets can aid in the assessment of injuries, and since these bullets are fabricated from non-ferromagnetic metals, their clear identification allows for magnetic resonance imaging (MRI) without the risk of bullet movement inside the body due to the magnetic pull of the MRI unit. Furthermore, this approach could be of great interest to forensic investigators if patients who received gunshot wounds underwent non-operative treatments and the projectile remains in the body. Since the use of CT is also increasing for medico-legal post-mortem examinations, the identification of lodged projectiles is of interest for a virtual autopsy or 'Virtopsy'.

Visualization and documentation of perimortem traits in long bone fractures using computed tomography

Perimortem fracture patterns in long bones, defined in previous publications, include layered breakage, bone scales, crushed margins, flakes with flake defect, wave lines, and plastic deformation. The traits help professionals during trauma analysis to differentiate peri- from post-mortem fractures. This study will therefore investigate whether these traits can be recorded with Computed Tomography (CT) as the non-invasive 3D imaging technique is becoming more popular in forensic science. CT scans of macerated bone samples (n = 15; humerus: n = 1; ulna: n = 1; radius: n = 1; femur: n = 12) were investigated using multi-planar reconstructions (MPRs) and volume renderings. Tension lines and severe plastic deformation were visible on the individual multi-planar reconstructions (MPRs) and the 3D models. Additionally, layered breakage and flake defects were also clearly distinguishable on the volume renderings. Based on the results, CT imaging may be a useful and fast tool to document, visualize, and analyze findings of blunt force trauma.

Postmortem CT in Trauma: An Overview

As forensic radiology sees an exponential gain in popularity, postmortem computed tomography (PMCT) is increasingly being used in the appropriate setting, either as preautopsy guidance or as part of complementary virtual autopsy protocol. Many articles have expounded the value it adds to forensic pathology in the general setting and the appropriate technical parameters to be used for optimum benefit. We aim to put forth a concise review on the role of PMCT specifically in trauma and the pitfalls to be aware of. Reviews have shown that presumed cause of death in trauma have been proven by autopsy to be wrong in about 30% cases. Radiology applied to postmortem investigation in unnatural deaths and more specifically in trauma shares many semiotic features with emergency radiology. Therefore, in the near future, emergency radiologists might be required to integrate this type of imaging in their regular practice. Although the predominant drawbacks are time-dependent, PMCT also has some difficulty in differentiating antemortem and postmortem events. However, in many such scenarios, PMCT and autopsy play a complementary role in arriving at conclusions, and we believe understanding the benefits and role in trauma is imperative considering the expanding usage of PMCT.

Postmortem Computed Tomography and Magnetic Resonance Imaging of Gunshot Wounds to the Neck

Postmortem magnetic resonance imaging (MRI) is rarely used for the radiologic assessment of gunshot injuries, although it has clear advantages over postmortem computed tomography (CT) with regard to the imaging of soft tissue injuries. Another benefit in using MRI is that lodged projectiles composed of nonferromagnetic material such as lead present only marginal metal artifacts compared with severe artifacts on CT. This case report presents CT and MRI findings in a case with two gunshot wounds to the neck: a perforating wound and a nonperforating wound with a lead bullet lodged in the cervical spine. The decedent underwent CT and MRI before the scheduled autopsy. A ring of radiopaque material under the dermis in the fatty tissue was identified at both entrance wounds on CT, which was indicative of contact shots. The perforating gunshot was clearly indicated on CT by bullet fragments along the wound channel through the perforated 6th cervical vertebra and the fractured cricoid cartilage at the exit wound. The second trajectory, however, was only assumed based on the presence of gunshot residues at the entrance wound and the position of the lodged bullet. The radiologic assessment was severely impeded by the metal artifacts on CT. Barely noticeable metal artifacts on MRI allowed for clear visualization of the soft tissue injuries and the ruptured medulla oblongata. Only MRI clarified the soft tissue injuries of the brainstem noninvasively, which could provide specific and graphic information on the rapidity of death and the incapacitation of the victim.