Development of CT-guided biopsy sampling for time-dependent postmortem redistribution investigations in blood and alternative matrices—proof of concept and application on two cases

Atypical postmortem redistribution in chronic methadone consumers

Available literature demonstrates that methadone is prone to moderate postmortem redistribution, but subject to high interindividual variability in the central to peripheral blood concentration ratios (C/P). In this case series, 10 cases of chronic methadone users displaying C/P < 1 (range 0.26-0.82) are described. Femoral, cardiac and ante-mortem blood concentrations of methadone and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) are reported for all cases, as well as sex, age, case history, results of the pathological investigation, other toxicological findings and cause and manner of death. EDDP blood concentrations, similar in both central and peripheral blood, as well as antemortem blood concentration results in Case 4, demonstrate that this atypical C/P < 1 finding is attributable to postmortem changes and not analytical or pre-analytical artifacts. Case 4 is a particularly instructive example, with femoral blood concentration (966 ng/mL) approximately twice as high as cardiac blood (499 ng/mL) and ante-mortem blood (418 ng/mL, collected 38 min prior to death)-clearly demonstrating that cardiac blood methadone concentration is more representative of the antemortem blood concentration in this case. In Case 4 and four others, toxicological interpretation based on femoral blood concentration alone would have been misleading. Based on these results and evidence from the literature, it is hypothesized that methadone bioaccumulates in the tissues of chronic users and redistributes from thigh tissues into femoral blood, increasing the concentration postmortem. This case series highlights how femoral blood is not always preserved from postmortem changes and that the analysis of multiple blood sources is necessary to avoid a misleading toxicological interpretation-particularly for cases of chronic methadone users.

Comparative Study of Postmortem Concentrations of Benzodiazepines and Z-Hypnotics in Several Different Matrices

Benzodiazepines and z-hypnotics are detected in the majority of fatal overdose cases in Norway, often in combination with other drugs of abuse, and their concentrations in peripheral blood (PB) might be important to elucidate the cause of death. In some forensic autopsies, PB is however not available. The aim of the present study was to compare concentrations of benzodiazepines and z-hypnotics in five alternative matrices to assess whether these concentrations are comparable to concentrations in PB. A total of 109 forensic autopsy cases were included. PB, cardiac blood (CB), pericardial fluid (PF), psoas muscle (PM), lateral vastus muscle (LVM) and vitreous humor (VH) from each case were analyzed using ultra high performance liquid chromatography--tandem mass spectrometry. We were able to detect clonazepam, 7-aminoclonazepam, flunitrazepam, 7-aminoflunitrazepam, nitrazepam, 7-aminonitrazepam, diazepam, nordiazepam, oxazepam, alprazolam, midazolam, zopiclone and zolpidem in all the analyzed matrices. Concentrations measured in VH were generally much lower than those of PB for all compounds except zopiclone. 7-Amino metabolite concentrations were high compared to the parent compounds, although less so for the muscle samples. Concentrations of the parent nitrobenzodiazepines in muscles were higher than those in PB, but for the other compounds, concentrations in muscle showed good correspondence with PB. Both CB and PF were viable alternative matrices for PB, although a larger variation and a tendency for higher concentrations in PF were observed. This study shows that CB, PM, LVM and PF can give comparable concentrations to PB for benzodiazepines and z-hypnotics, while VH was less suitable. The concentrations in alternative matrices must, however, be interpreted carefully.

Robotic Tissue Sampling for Safe Post-Mortem Biopsy in Infectious Corpses

In pathology and legal medicine, the histopathological and microbiological analysis of tissue samples from infected deceased is a valuable information for developing treatment strategies during a pandemic such as COVID-19. However, a conventional autopsy carries the risk of disease transmission and may be rejected by relatives. We propose minimally invasive biopsy with robot assistance under CT guidance to minimize the risk of disease transmission during tissue sampling and to improve accuracy. A flexible robotic system for biopsy sampling is presented, which is applied to human corpses placed inside protective body bags. An automatic planning and decision system estimates optimal insertion point. Heat maps projected onto the segmented skin visualize the distance and angle of insertions and estimate the minimum cost of a puncture while avoiding bone collisions. Further, we test multiple insertion paths concerning feasibility and collisions. A custom end effector is designed for inserting needles and extracting tissue samples under robotic guidance. Our robotic post-mortem biopsy (RPMB) system is evaluated in a study during the COVID-19 pandemic on 20 corpses and 10 tissue targets, 5 of them being infected with SARS-CoV-2. The mean planning time including robot path planning is 5.72±167s. Mean needle placement accuracy is 7.19± 422mm.

Postmortem Metabolomics: Strategies to Assess Time-Dependent Postmortem Changes of Diazepam, Nordiazepam, Morphine, Codeine, Mirtazapine and Citalopram

Postmortem redistribution (PMR) can result in artificial drug concentration changes following death and complicate forensic case interpretation. Currently, no accurate methods for PMR prediction exist. Hence, alternative strategies were developed investigating the time-dependent postmortem behavior of diazepam, nordiazepam, morphine, codeine, mirtazapine and citalopram. For 477 authentic postmortem cases, femoral blood samples were collected at two postmortem time-points. All samples were quantified for drugs of abuse (targeted; liquid chromatography-tandem mass spectrometry LC-MS/MS) and characterized for small endogenous molecules (untargeted; gas chromatography-high resolution MS (GC-HRMS). Trends for significant time-dependent concentration decreases (diazepam (n = 137), nordiazepam (n = 126)), increases (mirtazapine (n = 55), citalopram (n = 50)) or minimal median postmortem changes (morphine (n = 122), codeine (n = 92)) could be observed. Robust mathematical mixed effect models were created for the generalized postmortem behavior of diazepam and nordiazepam, which could be used to back-calculate drug concentrations towards a time-point closer to the estimated time of death (caution: inter-individual variability). Significant correlations between time-dependent concentration changes of morphine, mirtazapine and citalopram with individual endogenous molecules could be determined; no correlation was deemed strong enough for successful a posteriori estimation on the occurrence of PMR for specific cases. The current dataset did successfully lead to a significant knowledge gain in further understanding the time-dependent postmortem behavior of the studied drugs (of abuse).

The Future of Analytical and Interpretative Toxicology: Where are We Going and How Do We Get There?

(Forensic) toxicology has faced many challenges, both analytically and interpretatively, especially in relation to an increase in potential drugs of interest. Analytical toxicology and its application to medicine and forensic science have progressed rapidly within the past centuries. Technological innovations have enabled detection of more substances with increasing sensitivity in a variety of matrices. Our understanding of the effects (both intended and unintended) have also increased along with determination and degree of toxicity. However, it is clear there is even more to understand and consider. The analytical focus has been on typical matrices such as blood and urine but other matrices could further increase our understanding, especially in postmortem (PM) situations. Within this context, the role of PM changes and potential redistribution of drugs requires further research and identification of markers of its occurrence and extent. Whilst instrumentation has improved, in the future, nanotechnology may play a role in selective and sensitive analysis as well as bioassays. Toxicologists often only have an advisory impact on pre-analytical and pre-interpretative considerations. The collection of appropriate samples at the right time in an appropriate way as well as obtaining sufficient circumstance background is paramount in ensuring an effective analytical strategy to provide useful results that can be interpreted within context. Nevertheless, key interpretative considerations such as pharmacogenomics and drug-drug interactions as well as determination of tolerance remain and in the future, analytical confirmation of an individual's metabolic profile may support a personalized medicine and judicial approach. This should be supported by the compilation and appropriate application of drug data pursuant to the situation. Specifically, in PM circumstances, data pertaining to where a drug was not/may have been/was contributory will be beneficial with associated pathological considerations. This article describes the challenges faced within toxicology and discusses progress to a future where they are being addressed.

Time- and Site-Dependent Postmortem Redistribution of Antidepressants and Neuroleptics in Blood and Alternative Matrices

Postmortem redistribution (PMR) leads to challenges in postmortem case interpretation. Particularly antidepressants and neuroleptics are expected to undergo PMR based on their physico-chemical properties. For the current study, time- and site-dependent PMR of 20 antidepressants and neuroleptics were investigated in humans (authentic cases); five of which are discussed in detail (citalopram, mirtazapine, quetiapine, risperidone and venlafaxine) along with two metabolites (9-OH-risperidone and O-desmethylvenlafaxine). Blood [femoral (pB) and heart blood (HB)] and tissue biopsy samples (lung, kidney, liver, spleen, thigh muscle and adipose tissue) were collected upon admission to the institute utilizing a computed tomography-guided sample collection workflow (t1). Approximately 24 h later (t2; mean 23 ± 9.3 h), samples from the same body regions were collected manually. Liquid chromatography-tandem mass spectrometry was used for quantification. Most antidepressants and neuroleptics showed significant time-dependent concentration changes indicating the occurrence of PMR. For the first time, two phases of redistribution in pB for quetiapine were proposed (concentration decreases in the early postmortem phase, followed by concentration increases) and contrasting existing literature, both concentration increases and decreases in pB overtime were observed for risperidone and 9-OH-risperidone. Venlafaxine and its metabolite only showed minimal concentration changes, while citalopram exhibited a trend for concentration increases and mirtazapine for concentration decreases in pB overtime. Based on time-dependent tissue data, passive diffusion processes along the muscle-to-pB, liver-to-HB and lung-to-HB concentration gradients could be proposed along with bacterial degradation. Overall, no case interpretation had to be adjusted, which suggests that PMR changes of antidepressants and neuroleptics do not seem to be relevant for forensic case interpretation within the 24 h period that was investigated. However, limitations of the current study (e.g., temperature-controlled storage of the bodies) could have led to an underestimation of occurring postmortem changes, hence, interpretation of postmortem results should always be conducted with care, considering PMR phenomena and inter-individual variability.

Postmortem metabolomics: Correlating time-dependent concentration changes of xenobiotic and endogenous compounds

Postmortem redistribution (PMR) describes the artificial postmortem concentration changes of xenobiotics that may pose major challenges in forensic toxicology. Only a few studies have systematically investigated time-dependent postmortem drug concentration changes so far and the a posteriori estimation of the occurrence of PMR is not yet possible. In this context, the general concept that postmortem biochemical changes in blood might parallel drug redistribution mechanisms seems promising. Thus, the current study investigated the possible correlations between time-dependent postmortem concentration changes of xenobiotic and endogenous compounds; exemplified for authentic morphine (n = 19) and methadone (n = 11) cases. Peripheral blood samples at two time-points postmortem were analyzed for morphine and methadone concentrations and an (un)targeted postmortem metabolomics approach was utilized to combine targeted quantitative analysis of 56 endogenous analytes and untargeted screening for endogenous compounds (characterizing 1174 features); liquid and gas chromatography-mass spectrometry was used respectively. Individual statistically significant correlations between morphine/methadone and endogenous compounds/features could be determined. Hence, the general applicability of the proposed concept could successfully be confirmed. To verify the reproducibility and robustness of the correlating behavior, a larger dataset must be analyzed next. Once a marker/set of markers is found (e.g. robust correlation with specific xenobiotic or xenobiotic class), these could be used as surrogates to further study the time-dependent PMR in a broader variety of cases (e.g. independent of a xenobiotic drug present). A crucial next step will also be the attempt to create a statistical model that allows a posteriori estimation of PMR occurrence of xenobiotics to assist forensic toxicologists in postmortem case interpretation.

Pitfalls in drug testing by hyphenated low- and high-resolution mass spectrometry

This paper reviews various pitfalls observed during developing, validation, application, and interpretation of drug testing approaches using GC-MS and low- and high-resolution LC-MS. They include sampling and storage of body samples, sample adulteration and contamination, analyte stability, sample preparation without or with cleavage of conjugates, extraction, derivatization, internal standardization, false negative and positive results by GC-MS or LC-MS screening and/or confirmation procedures including artifact formation, ion suppression or enhancement by electrospray ionization, and finally pitfalls in data interpretation. Conclusions and prospects close the Tutorial.

Analytical considerations for postmortem metabolomics using GC-high-resolution MS

Metabolomics studies that aim to qualitatively and quantitatively characterize the entirety of small endogenous biomolecules in an organism are widely conducted in the clinical setting. They also become more and more popular in the field of forensics (toxicology), e.g., to assist in postmortem investigations by objective postmortem interval estimation. However, other issues in postmortem toxicology, such as the phenomenon of (time-dependent) postmortem redistribution, have not yet been tackled by metabolomics studies. Hence, the aim of the current study was to develop an (un)targeted gas chromatography-high-resolution mass spectrometry-based method for endogenous metabolites as a tool for large-scale (un)targeted human postmortem metabolomics investigations (e.g., to objectively assess PMR) with thorough analytical evaluation of this method to ensure fitness-to-purpose in terms of reliability and robustness. This was achieved by using a targeted metabolite subset (n = 56) and a targeted processing workflow. Evaluation experiments have shown that using an artificial matrix (revised simulated body fluid (rSBF) + 5% bovine serum albumin (BSA)) for calibration purposes, all parameters lay within the scope of the method (sensitivity, selectivity, calibration model, accuracy, precision, processed sample stability, and extraction efficiency). When applying this method to large-scale studies, samples should be run in randomized order if analysis time is expected to exceed 18-24 h and potential biomarkers that are found with this method should be verified by a specialized, targeted method (e.g., by using standard addition in authentic matrix for quantification purposes). Overall, the current method can be successfully used for conduction of time-dependent postmortem metabolomics investigations. Graphical abstract.

The forensic spleen: Morphological, radiological, and toxicological investigations

The spleen is only uncommonly investigated in the forensic setting. Thorough examinations are performed in some specific situations such as splenic trauma (including iatrogenic trauma from cardiopulmonary resuscitation attempts), anaphylaxis, drowning, and sepsis-related deaths. The aim of this review is to present the available literature focusing on a few selected splenic diseases as well as forensic investigations performed on the spleen in order to summarize the most frequent situations in which this routinely unexplored organ may merit more extensive examination.

Time-Dependent Postmortem Redistribution of Opioids in Blood and Alternative Matrices

Forensic postmortem case interpretation can be challenging, in particular due to postmortem redistribution (PMR) phenomena. Recent studies have shown that computed tomography (CT)-guided collection of biopsy samples using a robotic arm (virtobot) provides a valuable tool for systematic studies on time-dependent PMR. Utilizing this strategy, several cases involving opioid use such as methadone, fentanyl, tramadol, codeine, oxycodone and hydrocodone were evaluated for time-dependent concentration changes and potential redistribution mechanisms. Upon admission to the institute (t1), blood (femoral and right ventricle heart blood) and tissue biopsy samples (lung, kidney, liver, spleen, thigh muscle and adipose tissue) were collected utilizing CT-guided biopsy. Approximately 24 h later (t2; mean 28 ± 15 h), during the autopsy, samples from the same body regions were collected manually and in addition brain tissue, gastric content, urine and left ventricle heart blood. Analysis was conducted with liquid chromatography tandem mass spectrometry. Significant time-dependent methadone concentration increases in femoral blood (pB) indicate the occurrence of PMR, however, ultimately not relevant for forensic interpretation. The main metabolite of methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), showed a less significant trend for PMR. Redistribution by passive diffusion along the muscle-to-pB concentration gradient seems likely for methadone, but not for EDDP. Results for fentanyl suggest extensive PMR. Other opioids such as tramadol, codeine, hydrocodone and oxycodone showed no consistent trend for significant PMR. Overall, CT-guided biopsy sampling proved to be a valuable tool for the investigation of PMR mechanisms.

The forensic spleen: Morphological, radiological, and toxicological investigations

The spleen is infrequently investigated in forensic pathology routine. Thorough examinations are performed in very specific situations such as splenic trauma (including iatrogenic trauma from cardiopulmonary resuscitation attempts), anaphylaxis-related deaths, drowning and sepsis. The purpose of this review article is to provide a general overview of available literature focusing on a few selected splenic diseases as well as available forensic investigation techniques performed on the spleen in order to summarize the most frequent situations of forensic interest in which this routinely unexplored organ may merit more extensive examination.

[Cause of Death: 'Intoxication' - a Matter of the Concentration?]

Cause of Death: 'Intoxication' - a Matter of the Concentration? Abstract. Elucidation of the cause of death is one of the main reasons for medico-legal investigations. In clinical toxicology, the severity of a given poisoning is typically assessed with the blood concentration of a pharmacologically or toxicologically active compound. Such an interpretation proves to be difficult or even impossible in postmortem toxicology. Numerous biochemical and biological processes beginning immediately after death may render the calculated drug concentration unreliable. Concentrations obtained from postmortem samples do not necessarily reflect the blood concentration at the time of death. A prediction if and to what extent such postmortem changes might have occurred is still impossible for individual cases. Interpretation therefore needs to be done with care, considering case circumstances and all available information.

Postmortem distribution and redistribution of MDAI and 2-MAPB in blood and alternative matrices

Intoxication cases involving new psychoactive substances (NPS) provide several challenges for forensic toxicologists as data on pharmacodynamic and pharmacokinetic properties are lacking, especially on potency and toxicity. Furthermore, reference values and information on postmortem redistribution (PMR) do not exist so far for most NPS. A fatal case involving the amphetamine-derivatives MDAI (5,6-methylenedioxy-2-aminoindane) and 2-MAPB (1-(benzofuran-2-yl)-N-methylpropan-2-amine) was investigated at the Zurich Institute of Forensic Medicine. At admission at the institute approx. 11h after death (first time point, t1), femoral and heart blood (right ventricle) was collected using computed tomography (CT)-guided biopsy sampling. At autopsy (t2), samples from the same body regions as well as various tissue samples were collected manually. In addition, an antemortem blood sample collected 6h before death was available. MDAI and 2-MAPB were quantified using a validated LC-MS/MS method. A significant concentration decrease between the antemortem and the first peripheral postmortem blood sample was observed, which most probably can be explained by remaining metabolism and excretion within the last 6h prior to death. No significant concentration change was observed between the two postmortem heart blood and peripheral blood samples. Accordingly, MDAI and 2-MAPB did not seem to undergo relevant postmortem redistribution in peripheral and heart blood in the presented case. This is the first study on postmortem redistribution of the new psychoactive substances MDAI and 2-MAPB. However, more studies covering more cases are necessary to generate universal statements on the PMR with these two NPSs.

Freezing preparation for macroscopic forensic investigation in putrefied brain

PURPOSE

To evaluate the usefulness of the applied freezing technique in putrefied brain for macroscopic investigation.

MATERIALS AND METHODS

From October 2015 to September 2016, first the brains of 10 cadavers (control group: male 6, female 4, age 20-80 (mean 61.5), postmortem intervals (PMI) 14-75 (mean 29.7)days) were inspected following the standard practice (without freezing preparation), and then with 10 cadavers (freezing group: male 7, female 3, age 41-88 (mean 60.4), PMI 7-75 (mean 29.2)days) the freezing technique was used before the autopsy. The cut brain was investigated, and the gray-white matter difference was evaluated macroscopically.

RESULTS

In the control group, the brain parenchyma leaked out like sludge in 5, and there was difficulty maintaining its structure in 7. The gray-white matter difference was well visible in 3, but hard to distinguish in 3, and the total scores ranged from 0 to 9 (mean 4.4) points. In the freezing group, the entire putrefied brain was extracted as a solid organ, the gray-white matter differences were well visible, and the total scores were 6.7-9 (8.3) points. The gray-white matter difference was preserved in the freezing group (p<0.05).

CONCLUSION

The freezing procedures to evaluate the putrefied brain have been successfully applied, and it could be statistically more useful in putrefied brain investigation than the ordinary procedure. Postmortem CT can be useful to evaluate not only the degree of brain putrefaction, but also the degree of brain parenchyma freezing.