The idea of injecting substances into the blood vessels of a corpse to make them visible is not new. However, in the forensic context, post-mortem angiography (PMA) experienced a significant upswing in the 2000s. For the first time, different substances were systematically evaluated for their applicability, visibility and user-friendliness for vascular imaging in the context of post-mortem computed tomography angiography (PMCTA). Since the first publication of a standardized protocol for the use of paraffin oil and Angiofil® as contrast agents, PMCTA has been made comparable, standardized and simplified for the first time.
However, this paraffin oil-Angiofil® mixture cannot be used in cases, when the focus is on the detection of a fat embolism which may be the cause of death or a sign of vitality during trauma. Polyethylene glycol 200 (PEG) mixed with Accupaque® may be considered as an alternative contrast agent mixture. However, there was no standard protocol for these fluids. In our work, a protocol for the standardized use of PEG-Accupaque® was developed. A total of 23 angiographies showed that the best image quality was obtained with a mixing ratio of 1:15 (Accupaque®300:PEG200). A perfusion volume of 1000 ml in the arterial, 1400 ml in the venous and 350 ml in the dynamic phase proved to be optimal. The infusion rates described by Grabherr et al. were confirmed for the three phases.
During the development of this protocol, changes in the tissue were observed that had not been adequately described in the literature. Therefor, organ and tissue samples were collected during an autopsy without prior PMCTA and stored in polyethylene glycol or oil in a jar at room temperature. The condition of the samples was recorded and documented during autopsy, 24 hours, 48 hours and 72 hours. It was found that the samples stored in PEG showed a clear hardening of the structures. We attribute this to the hygroscopic properties of the fluid. In addition, blood agglomerates appeared in the previously liquid blood . These are important changes that medical examiners performing autopsies after PMCTA with PEG should be aware of. The tissue samples stored in oil showed the (expected) putrefactive changes, without any significant changes due to the contrast agent.
In order to study not only the "hardware" of a PMCTA, further developments in radiological software were also investigated. In a clinical context, Cinematic Rendering Technique (CRT) software is often used for three-dimensional (3D) imaging. However, it has not been widely used in forensic radiology. Forensic radiology reports are generally prepared for medical laypersons such as police officers, judges, lawyers and prosecutors. Complex pathologies are presented in 3D image reconstructions to make them easier to understand. In order to find out whether CRT in forensic radiology improves the comprehensibility of images, a questionnaire-based survey was carried out among the PMCTA's lay clients and forensic physicians. The images created in the Cinematic Rendering software were compared with those created by the regularly used 3D software "Volume Rendering Technique" (VRT). The study showed a positive trend that CRT may be more understandable than VRT. As a result, not only medical laypersons but also forensic physicians found CRT to be beneficial.
