Tissue microscopic changes and artifacts in multi-phase post-mortem computed tomography angiography in a hospital setting: a fatal case of systemic vasculitis

Development of a protocol for standardized use of a water-soluble contrast agent with polyethylene glycol in post-mortem CT angiography

Computed tomography angiography (PMCTA) is increasingly used in postmortem cases. Standardized validated protocols permit to compare different PMCTA images and make it more easily to defend a case in court. In addition to the well-known technique by Grabherr et al. (2011) which is using paraffin oil as a carrier substance, water-soluble polyethylene glycol 200 (PEG200) can be used in combination with the contrast agent Accupaque® 300. As to date, there exists no standardized protocol for the use of this contrast agent mixture, the aim of this study was to develop a protocol using it. Between 2012 and 2022, 23 PMCTA with PEG200 and Accupaque®300 were performed at the University Centre of Legal Medicine Lausanne (Switzerland) and the Institute of Forensic Medicine Munich (Germany). The images obtained were evaluated regarding the opacification of the vessels and possible artefacts. The best image quality was obtained with a mixing ratio of 1:15 (Accupaque®300:PEG200) and a perfusion volume of 1000 ml in the arterial, 1400 ml in the venous and 350 ml in the dynamic phase. The infusion rates described by Grabherr et al. were confirmed for the three phases. Overall, the opacification of the vessels was diagnostically sufficient. In 13 cases no opacification of the right coronary artery was observed due to a stratification artefact. By using the PMCTA protocol with PEG200 as a carrier, a good overall image quality can be achieved. This protocol offers the possibility to standardize PMCTA with PEG200.

Histomorphological assessment of isolated abdominal organs after targeted perfusion with the contrast agent Angiofil® in postmortem computed tomography angiography

The current literature about histological alterations and artefacts associated with postmortem computed tomography angiography (PMCTA) is scarce and limited to qualitative research. The aim of this study was to describe and quantify histological alterations and artefacts in histologic specimens of the inner organs. The spleen, the liver, the kidneys and the pancreas were eviscerated in the course of standard forensic autopsy, followed by manual arterial and venous perfusion of the organs with the lipophilic contrast agent Angiofil®. Computed tomography (CT) of the organ packages was executed to evaluate if the perfusion with Angiofil® was sufficient. The CT scans revealed a good delineation of the vessel trees up to the organ periphery, suggesting a sufficient perfusion. Tissue samples were taken before and after perfusion, stained with hematoxylin-eosin (H&E) and examined by using microscopy. Native and perfused specimens were assessed on the basis of a qualitative rating scale in regard to the integrity of the cells, the tissue architecture and induced alterations. Subsequently the observed differences before and after perfusion with Angiofil® were analyzed quantitatively. While the liver, spleen and kidneys could be evaluated, further microscopic examinations of the pancreatic tissue were not possible due to vast autolytic changes. On the cellular level no changes in the liver, spleen and kidneys were observed after administering Angiofil®. While the tissue architecture of these organs remained intact, a significant blood volume displacement occurred. As a consequence, tissue with hypoemic or normal blood state demonstrated congestion. Further, optically empty spaces emerged regularly in the vessels and the parenchyma of each organ as a surrogate for the lipophilic contrast agent. With a few exceptions an adequate perfusion up to the microscopic level was observed. Following the results of this investigation, CT-controlled manual injection of Angiofil® into isolated organs may be an alternative to the generalized in situ application of contrast agents in the course of PMCTA. It is of eminent importance to know the artefacts induced by an Angiofil® injection in order to avoid a misinterpretation or a masking of findings. Thus, a collection of native tissue specimens has to be done before contrast agent application.

Towards multi-phase postmortem CT angiography in children: a study on a porcine model

PURPOSE

Multi-phase postmortem computed tomography angiography (MPMCTA) is a growing technique, which is standardized for adults. Application of this protocol for a children population is not so well defined. Our study aims to adapt the adult's protocol to children, using a porcine model.

MATERIAL AND METHODS

Three groups of 18 pigs were studied, with a weight distribution between 4 and 48 kg. Different pump devices were used. Pigs of group I were studied using the Virtangio® machine, whereas pigs of groups II and III were studied using used the Medrad® machine. Study of vascular opacification was possible using a semi-quantitative method based on 26 arterial and 26 venous segments that were distributed over the entire body from the cephalic extremity to the posterior pawns.

RESULTS

While thoracic, abdominal, and pelvic vascular opacification were complete for each individual pig in a group, group III showed better vascular opacification for the cephalic extremity. This was also true for anterior and posterior pawns vascular opacification. Spearman correlation tests showed a significant relationship between anthropometric characteristics of pigs, injection parameters, and percentage of opacified segments. A higher percentage of opacification was obtained for individuals of lower weights, with comparatively lower quantities of contrast agent injected.

CONCLUSION

Postmortem computed tomography angiography (PMCTA) was possible for all the individuals, particularly for small weights (4 kg) using the Medrad® machine. However, further studies are needed to better understand the procedure.

The effect of post-mortem computed tomography angiography (PMCTA) using water-soluble, iodine-based radiographic contrast on histological analysis of the liver, kidneys and left ventricle of the heart

The purpose of this study was to investigate the impact of post-mortem computed-tomography angiography (PMCTA) on the histology of the liver, kidneys and heart. Multiple tissue cores were collected from the liver, left and right kidneys and left ventricle utilizing CT-guided biopsy. Subsequent whole body PMCTA was performed using a solution of polyethylene glycol and iodinated radiographic contrast, and an embalming pump. Corresponding biopsy cores were collected at autopsy, and blinded histology analysis assessing for PMCTA-induced histology artefact was performed. The blinded analysis of pre-PMCTA and post-PMCTA biopsy samples demonstrated that whole body PMCTA had no effect on the histological analyses of the liver (0%, CI = 0-13.7%), left ventricle of the heart (0%, CI = 0-36.9%) and right kidney (0%, CI = 13.2%), however likely caused increased Bowman's capsule spaces in the left kidney of one case (4%, CI = 0.01-20.4%). Other artefactual histological changes identified included eosinophilic material in the liver, whiter interstitium and dilated tubules in kidney samples, and autolysis-related changes, however these could not be categorically attributed to the PMCTA procedure. PMCTA causes zero or minimal effect to the histological examination of the liver, left kidney, right kidney and left ventricle, and as such performing PMCTA prior to autopsy is unlikely to impact autopsy histological results in these organs.

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.

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.