[Postmortem CT-angiography: feasibility of US-guided vascular access]

A Practical Guide to Virtual Autopsy: Why, When and How

Postmortem imaging is considered a routine investigative modality in many forensic institutions worldwide. Because of its ability to provide a quick and complete documentation of skeletal system and major parenchymal alterations, postmortem computed tomography (PMCT) is the imaging technique most frequently applied in postmortem forensic investigations. Also postmortem magnetic resonance has been implemented in postmortem setting, but its use is mostly limited to focused analysis (eg, study of the heart and brain). PMCT presents some limits in investigating "natural" deaths, particularly related to its poor ability in differentiating soft tissue interfaces and in depicting vascular lesions. For this reason, PMCT angiography has been introduced. A major limitation of these postmortem imaging techniques is the absence of body samples for histopathologic, toxicologic, or microbiological analysis. This limit has been overcome by the introduction of postmortem percutaneous biopsies. The aim of this review is to provide a practical guide for virtual autopsy, with the intent of facilitating standardization and augmenting its quality. In particular, the indications of virtual autopsy as well protocols in PMCT examinations and its ancillary techniques will be discussed. Finally, the workflow of a typical virtual autopsy and its main steps will be described.

Evolution of post-mortem coronary imaging: from selective coronary arteriography to post-mortem CT-angiography and beyond

Since the 1970s, remarkable efforts have been made in the post-mortem coronary study, especially by angiography, as an added tool to diagnose heart-related deaths. In more recent times, post-mortem CT (PMCT) and post-mortem CT-angiography (PMCTA) have become an established practice in numerous forensic units, because of the undeniable advantages these diagnostic instruments can offer: data acquisition times are increasingly fast, costs have become lower and, once acquired, data can be re-utilized and re-evaluated at any given time. This review aims to chart the history of post-mortem cardiac imaging, highlighting its evolution both in terms of methodology and technology as well as the contribution that forensic radiology has been able to offer to forensic pathology, not as an alternative to autopsy but as a guide and aid when performing one. Finally, the latest advances in the study of cardiac deaths are explored, namely by cardiac post-mortem MRI (PMMR), able to visualize all the various stages of a myocardial infarction, post-mortem MRI-angiography (PMMRA), useful in investigating coronary artery pathology and post-mortem cardiac micro-CT, able to provide near-histological levels of myocardial, coronary and valvular detail.

Modern post-mortem imaging: an update on recent developments

Modern post-mortem investigations use an increasing number of digital imaging methods, which can be collected under the term "post-mortem imaging". Most methods of forensic imaging are from the radiology field and are therefore techniques that show the interior of the body with technologies such as X-ray or magnetic resonance imaging. To digitally image the surface of the body, other techniques are regularly applied, e.g. three-dimensional (3D) surface scanning (3DSS) or photogrammetry. Today's most frequently used techniques include post-mortem computed tomography (PMCT), post-mortem magnetic resonance imaging (PMMR), post-mortem computed tomographic angiography (PMCTA) and 3DSS or photogrammetry. Each of these methods has specific advantages and limitations. Therefore, the indications for using each method are different. While PMCT gives a rapid overview of the interior of the body and depicts the skeletal system and radiopaque foreign bodies, PMMR allows investigation of soft tissues and parenchymal organs. PMCTA is the method of choice for viewing the vascular system and detecting sources of bleeding. However, none of those radiological methods allow a detailed digital view of the body's surface, which makes 3DSS the best choice for such a purpose. If 3D surface scanners are not available, photogrammetry is an alternative. This review article gives an overview of different imaging techniques and explains their applications, advantages and limitations. We hope it will improve understanding of the methods.

Back to the Future - Part 2. Post-mortem assessment and evolutionary role of the bio-medicolegal sciences

Part 2 of the review "Back to the Future" is dedicated to the evolutionary role of the bio-medicolegal sciences, reporting the historical profiles, the state of the art, and prospects for future development of the main related techniques and methods of the ancillary disciplines that have risen to the role of "autonomous" sciences, namely, Genetics and Genomics, Toxicology, Radiology, and Imaging, involved in historic synergy in the "post-mortem assessment," together with the mother discipline Legal Medicine, by way of its primary fundament, universally denominated as Forensic Pathology. The evolution of the scientific research and the increased accuracy of the various disciplines will be oriented towards the elaboration of an "algorithm," able to weigh the value of "evidence" placed at the disposal of the "justice system" as real truth and proof.

Technical note: A preliminary comparative study between classical and interventional radiological approaches for multi-phase post-mortem CT angiography

PURPOSE

Multi-phase post-mortem computed tomography angiography (MPMCTA) is a new diagnostic tool, used in forensic pathology. On the one hand, this technique allows a better and direct visualization of vascular and solid organ lesions. On the other hand, the invasiveness of the procedure-which requires surgical denudation (inguinal and/or cervical) and the insertion of surgical cannulas-leads to many relatives refusing scientific autopsies. Our hypothesis states that a minimally-invasive procedure combining interventional radiological techniques with MPMCTA (replacement of surgical cannulas by radiological catheters) will improve the approval rate of scientific autopsies by families. The aim of this study was to evaluate the feasibility of the minimally-invasive MPMCTA approach and to compare its performance to the current reference-standard (the conventional approach).

MATERIAL AND METHODS

We included consecutively 16 corpses divided in two groups according to the contrast enhancement approach: radiological catheters (n=8), and surgical cannulas (n=8). Corpses were chosen and assigned randomly from our local data. The quality of the imaging procedure was compared according to four items: global vascular opacification, cerebral venous opacification, and lower limbs opacification (arterial and venous).

RESULTS

A minimally-invasive approach for scientific autopsies is feasible through a radiological catheter. Vascular opacification was optimal in 8 out of 8 cases and was no less effective than the control reference group using surgical cannula incision associated with their non-occlusive aspects.

Multiphase Postmortem Computed Tomography Angiography in Pediatrics: A Case Report

Postmortem imaging techniques, especially postmortem computed tomography, have become integral tools in forensic investigations. Multiphase postmortem computed tomography angiography (MPMCTA) visualizes the vascular system in detail and makes it possible to evaluate the perfusion of even the smallest vessels. Although the technique has been well described for adults, no pediatric cases have been reported and no pediatric protocol has been established for this type of investigation. We present the case a 7-year-old child for which we used a previously described MPMCTA protocol and adapted values of perfusion, with the same technical equipment as for adult cases. Our main objective was to propose a perfusion protocol adapted for the investigation of infants and children. Moreover, we discuss both the difficulties that we encountered and possible ways to further improve the investigation of pediatric cases by MPMCTA.

The usefulness of post-mortem CT angiography in injuries caused by falling from considerable heights: three fatal cases

OBJECTIVE

Post-mortem computed tomography is a diagnostic tool forming part of the arsenal available to forensic pathologists today. In addition to its usefulness in detecting bone lesions, which has long been recognized, this technique has nowadays been enhanced by the development of CT angiography. The role of multiphase post-mortem computed tomography angiography (multiphase PMCTA) is primordial, improving detection of solid organ lesions and permitting vascular lesions to be visualized directly.

MATERIAL AND METHODS

Our paper presents a series of three deaths by falling from a considerable height recorded since the beginning of 2012. We report the usefulness of PMCTA and the various mechanisms involved in the trauma.

RESULTS

Most of the lesions were diagnosed by both PMCTA and autopsy, including the rare lesions, but the peripheral bone lesions and the hemopneumatocele were diagnosed only by PMCTA, while dislocation of vertebrae and the testicular fractures were detected solely by autopsy.

CONCLUSION

PMCTA is a new, minimally-invasive technique which, combined with autopsy, provides better visualization and detection of certain lesions, particularly in the case of death by falling from a great height.

Postmortem-computed tomography and postmortem-computed tomography-angiography: a focused update

The use of multidetector CT (MDCT) represents a reality routinely used in several forensic institutes, for the numerous advantages that this diagnostic tool can provide; costs are becoming increasingly lower; data acquisition is always faster and once acquired may be revalued at any time. However, there are also some diagnostic limitations, for example, the visualization of the vascular system or a limited soft tissue contrast. In order to overcome these limitations, in recent years, contrast medium has been introduced in postmortem cases, with the development of several techniques of PMCT angiography (PMCTA) and standardized protocols to make them easily reproducible. The aim of this review is to highlight the advantages and pitfalls of PMCT and PMCTA in forensic investigation, taking into consideration the broad spectrum of applications both for natural and unnatural deaths and the numerous methods currently used. Secondly, in the light of the considerable progress in this field and the attempt to develop standardized protocols of PMCTA, the authors aim to evaluate the diagnostic value of PMCTA in comparison both to PMCT and conventional autopsy.

Application of contrast media in post-mortem imaging (CT and MRI)

The application of contrast media in post-mortem radiology differs from clinical approaches in living patients. Post-mortem changes in the vascular system and the absence of blood flow lead to specific problems that have to be considered for the performance of post-mortem angiography. In addition, interpreting the images is challenging due to technique-related and post-mortem artefacts that have to be known and that are specific for each applied technique. Although the idea of injecting contrast media is old, classic methods are not simply transferable to modern radiological techniques in forensic medicine, as they are mostly dedicated to single-organ studies or applicable only shortly after death. With the introduction of modern imaging techniques, such as post-mortem computed tomography (PMCT) and post-mortem magnetic resonance (PMMR), to forensic death investigations, intensive research started to explore their advantages and limitations compared to conventional autopsy. PMCT has already become a routine investigation in several centres, and different techniques have been developed to better visualise the vascular system and organ parenchyma in PMCT. In contrast, the use of PMMR is still limited due to practical issues, and research is now starting in the field of PMMR angiography. This article gives an overview of the problems in post-mortem contrast media application, the various classic and modern techniques, and the issues to consider by using different media.

Postmortem cardiac imaging in fetuses and children

Fetal and pediatric cardiac autopsies have a crucial role in the counseling of parents with regard to both the cause of death of their child and the implications of such findings for future pregnancies, as well as for quality assurance of antenatal screening programs and antemortem diagnostic procedures. Postmortem imaging allows an opportunity to investigate the heart in situ prior to dissection, and both postmortem CT and postmortem MRI have shown excellent accuracy in detecting the majority of clinically significant cardiac lesions in the perinatal and pediatric population. As less-invasive autopsy becomes increasingly popular, clinical guidelines for maximal diagnostic yield in specific circumstances can be developed.

Multi-phase postmortem CT angiography (MPMCTA): a new axillary approach suitable in fatal thromboembolism

Postmor tem computed tomography is widely used in the forensic pathology setting as supplementing medico-legal investigations and being capable of providing significant data that affect final conclusions and adding new quality to recording postmortem observations. The integration with angiographic methods [postmortem computed tomography angiography and multiphase postmortem CT angiography (MPMCTA)] allows the examination of the cardiovascular system and it is increasingly being utilised in the field of forensic pathology. However, using the standardised procedure that establishes the femoral vessels on one side of the corpse as an access point to the vascular system, visualisation of the vascular tree below the cannula insertion site is excluded. Consequently, visualisation of the vascular anatomy and morphology of the lower limbs is impossible and lesions such as thrombosis of the superficial and deep venous system may remain elusive. Bearing in mind the high incidence of pulmonary thromboembolism in forensic case studies and the difficulties in postmortem diagnosis, we propose a new axillary approach for MPMCTA that allows the full detection of the vascular system of the lower limbs.

Advances in post-mortem CT-angiography

Performing a post-mortem multidetector CT (MDCT) scan has already become routine in some institutes of forensic medicine. To better visualize the vascular system, different techniques of post-mortem CT-angiography have been explored, which can essentially be divided into partial- and whole-body angiography techniques. Probably the most frequently applied technique today is the so-called multiphase post-mortem CT-angiography (MPMCTA) a standardized method for investigating the vessels of the head, thorax and abdomen. Different studies exist, describing its use for medicolegal investigations, and its advantages as well as its artefacts and pitfalls. With the aim to investigate the performance of PMCTA and to develop and validate techniques, an international working group was created in 2012 called the "Technical Working Group Post-mortem Angiography Methods" (TWGPAM). Beyond its primary perspective, the goals of this group include creating recommendations for the indication of the investigation and for the interpretation of the images and to distribute knowledge about PMCTA. This article provides an overview about the different approaches that have been developed and tested in recent years and an update about ongoing research in this field. It will explain the technique of MPMCTA in detail and give an outline of its indications, application, advantages and limitations.

Feasibility of resuscitation contrast-enhanced postmortem computed tomography using cardiopulmonary resuscitation technique with chest compression immediately after death

Purpose

Our purpose was to evaluate image delineation ability of contrast-enhanced post-mortem computed tomography (CEPMCT) using cardiopulmonary resuscitation technique of chest compression, named “resuscitation CEPMCT”.

Materials and methods

Non-traumatically-deceased 15 subjects (7 men; 8 women) aged 19–87 years (mean 61 years) underwent resuscitation CEPMCT. The contrast-enhanced technique, while injecting 100 ml of contrast media from the right cubital vein at a rate of 1 ml/s, chest compression was performed for 2 minutes at a rate of 100 times/min (a total of 200 times). CT attenuation values (Hounsfield Unit: HU) were measured in 8 target vessels: 1) pulmonary artery, 2) coronary artery, 3) ascending aorta, 4) abdominal aorta, 5) celiac trunk, 6) common iliac artery, 7) superior vena cava, and 8) inferior vena cava. One-sided Student’s t-test was performed to assess whether measured values were higher than 140 HU by setting p-value at 0.05.

Results

Measured CT values in the 8 vessels were 1) pulmonary artery: 325 ± 140 HU, 2) coronary artery: 240 ± 73 HU, 3) ascending aorta: 321 ± 127 HU, 4) abdominal aorta: 286 ± 96 HU, 5) celiac trunk: 233 ± 62 HU, 6) common iliac artery: 260 ± 114 HU, 7) superior vena cava: 422 ± 187 HU, and 8) inferior vena cava: 301 ± 142 HU, showing significantly higher values than the threshold value of 140 HU. Resuscitation CEPMCT detected one case of pulmonary arterial thromboemboli death.

Conclusion

Resuscitation CEPMCT using chest compression immediately after death has the possibility of detecting thromboembolus in major vessels, despite the simplicity of the technique.

Electronic supplementary material

The online version of this article (doi:10.1186/2193-1801-2-663) contains supplementary material, which is available to authorized users.