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

Abstract

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.

Temperature dependence of viscosity, relaxation times (T1, T2) and simulated contrast for potential perfusates in post-mortem MR angiography (PMMRA)

“…The usefulness of both post-mortem CT (PMCT), its extension post-mortem CT angiography (PMCTA) and post-mortem MRI (PMMR) as adjuncts in the context of forensic autopsies has been established, and these techniques are increasingly being implemented around the world [2, 3]. PMCT clearly visualises the skeletal system, whilst PMCTA, introduced approximately 10 years ago, delivers an ideal visualisation of the vascular system [4–8]. Finally, PMMR offers excellent soft-tissue contrast which would otherwise be unachievable.…”

“…However, challenges related to infrastructure, the complexity of PMMR (e.g. temperature-dependent contrast) and the influence of post-mortem changes have led to a slower advancement of this technique [4]. …”

“…Most recently, initial experience has been gained with post-mortem MR angiography (PMMRA) [4]. The technical feasibility of PMMRA was demonstrated using a small cohort; however, sedimentation problems negatively affected image quality [4, 17].…”

“…The technical feasibility of PMMRA was demonstrated using a small cohort; however, sedimentation problems negatively affected image quality [4, 17]. A PMMRA acquisition protocol for ex situ hearts using a lipophilic contrast agent mixture (paraffin oil and Angiofil®) can also be found in the literature [18]; however, to our knowledge, a systematic evaluation of potentially suitable perfusates and imaging protocols in the context of PMMRA has not yet been undertaken.…”

Postmortem CT Angiography Compared with Autopsy: A Forensic Multicenter Study

“…Consequently, various postmortem angiographic techniques have been developed (10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Probably the most widespread single approach for postmortem angiography today is multiphase postmortem CT angiography (20)(21)(22)(23)(24)(25)(26)(27), first described in 2011 (14).…”