Current issues in postmortem imaging of perinatal and forensic childhood deaths

Perinatal autopsy practice is undergoing a state of change with the introduction of evidence-based cross-sectional imaging, driven primarily by parental choice. In particular, the introduction of post mortem magnetic resonance imaging (PMMR) has helped to advance less-invasive perinatal autopsy in the United Kingdom (UK) and Europe. However, there are limitations to PMMR and other imaging techniques which need to be overcome, particularly with regard to imaging very small fetuses. Imaging is also now increasingly used to investigate particular deaths in childhood, such as suspected non-accidental injury (NAI) and sudden unexpected death in infancy (SUDI). Here we focus on current topical developments the field, with particular emphasis on the application of imaging to perinatal autopsy, and pediatric forensic deaths. Different imaging modalities and their relative advantages and disadvantages are discussed, together with other benefits of more advanced cross-sectional imaging which currently lie in the research domain. Whilst variations in local imaging service provision and need may determine different practice patterns, and access to machines and professionals with appropriate expertise and experience to correctly interpret the findings may limit current practices, we propose that gold standard perinatal and pediatric autopsy services would include complete PMMR imaging prior to autopsy, with PMCT in suspicious childhood deaths. This approach would provide maximal diagnostic yield to the pathologist, forensic investigator and most importantly, the parents

Multiple Cardiac Rhabdomyomas Visualised Using Micro-CT in a Case of Tuberous Sclerosis

Cardiac rhabdomyoma is the most common tumour of the heart in infancy and childhood, representing approximately 60% of all primary cardiac tumours in these age groups. Though they have a tendency to regress with advancing age and are histologically benign, rhabdomyomas may cause mechanical obstruction to blood flow, arrhythmia, congestive cardiac failure and death and may be associated with underlying genetic syndromes such as tuberous sclerosis. We present the case of a primigravida in her early 20s with no significant medical history who was referred to the Fetal Medicine Unit at 34 weeks' gestation following the detection of an irregular fetal heartbeat. An anomaly scan at 20 weeks had been reported as normal

Quantification of Maceration Changes using Post Mortem MRI in Fetuses

BACKGROUND: Post mortem imaging is playing an increasingly important role in perinatal autopsy, and correct interpretation of imaging changes is paramount. This is particularly important following intra-uterine fetal death, where there may be fetal maceration. The aim of this study was to investigate whether any changes seen on a whole body fetal post mortem magnetic resonance imaging (PMMR) correspond to maceration at conventional autopsy. METHODS: We performed pre-autopsy PMMR in 75 fetuses using a 1.5 Tesla Siemens Avanto MR scanner (Erlangen, Germany). PMMR images were reported blinded to the clinical history and autopsy data using a numerical severity scale (0 = no maceration changes to 2 = severe maceration changes) for 6 different visceral organs (total 12). The degree of maceration at autopsy was categorized according to severity on a numerical scale (1 = no maceration to 4 = severe maceration). We also generated quantitative maps to measure the liver and lung T2. RESULTS: The mean PMMR maceration score correlated well with the autopsy maceration score (R(2) = 0.93). A PMMR score of ≥4.5 had a sensitivity of 91%, specificity of 64%, for detecting moderate or severe maceration at autopsy. Liver and lung T2 were increased in fetuses with maceration scores of 3-4 in comparison to those with 1-2 (liver p = 0.03, lung p = 0.02). CONCLUSIONS: There was a good correlation between PMMR maceration score and the extent of maceration seen at conventional autopsy. This score may be useful in interpretation of fetal PMMR

Perinatal and paediatric post-mortem magnetic resonance imaging (PMMR): sequences and technique

As post-mortem MRI (PMMR) becomes more widely used for investigation following perinatal and paediatric deaths, the best possible images should be acquired. In this article, we review the most widely used published PMMR sequences, together with outlining our acquisition protocol and sequence parameters for foetal, perinatal and paediatric PMMR. We give examples of both normal and abnormal appearances, so that the reader can understand the logic behind each acquisition step before interpretation, as a useful day-to-day reference guide to performing PMMR

Lung aeration on post-mortem magnetic resonance imaging is a useful marker of live birth versus stillbirth.

Aim of this study was to investigate whether lung assessment on post-mortem magnetic resonance imaging (PMMR) can reliably differentiate between live birth and stillbirth

Health professionals’ and coroners’ views on less invasive perinatal and paediatric autopsy: a qualitative study

OBJECTIVE: To assess health professionals’ and coroners’ attitudes towards non-minimally and minimally invasive autopsy in the perinatal and paediatric setting. METHODS: A qualitative study using semistructured interviews. Data were analysed thematically. RESULTS: Twenty-five health professionals (including perinatal/paediatric pathologists and anatomical pathology technologists, obstetricians, fetal medicine consultants and bereavement midwives, intensive care consultants and family liaison nurses, a consultant neonatologist and a paediatric radiologist) and four coroners participated. Participants viewed less invasive methods of autopsy as a positive development in prenatal and paediatric care that could increase autopsy rates. Several procedural and psychological benefits were highlighted including improved diagnostic accuracy in some circumstances, potential for faster turnaround times, parental familiarity with imaging and laparoscopic approaches, and benefits to parents and faith groups who object to invasive approaches. Concerns around the limitations of the technology such not reaching the same levels of certainty as full autopsy, unsuitability of imaging in certain circumstances, the potential for missing a diagnosis (or misdiagnosis) and de-skilling the workforce were identified. Finally, a number of implementation issues were raised including skills and training requirements for pathologists and radiologists, access to scanning equipment, required computational infrastructure, need for a multidisciplinary approach to interpret results, cost implications, equity of access and acceptance from health professionals and hospital managers. CONCLUSION: Health professionals and coroners viewed less invasive autopsy as a positive development in perinatal and paediatric care. However, to inform implementation a detailed health economic analysis and further exploration of parental views, particularly in different religious groups, are required

Imaging the human placental microcirculation with micro-focus computed tomography: Optimisation of tissue preparation and image acquisition

Micro-CT provides 3D volume imaging with spatial resolution at the micrometre scale. We investigated the optimal human placenta tissue preparation (contrast agent, perfusion pressure, perfusion location and perfusion vessel) and imaging (energy, target material, exposure time and frames) parameters. Microfil (Flow Tech, Carver, MA) produced better fill than Barium sulphate (84.1%(±11.5%)vs70.4%(±18.02%) p = 0.01). Perfusion via umbilical artery produced better fill than via chorionic vessels (83.8%(±17.7%)vs78.0%(±21.9%), p < 0.05), or via umbilical vein (83.8%(±16.4%)vs69.8%(±20.3%), p < 0.01). Imaging at 50 keV with a molybdenum target produced the best contrast to noise ratio. We propose this method to enable quantification and comparison of the human fetoplacental vascular tree

Diagnostic accuracy of postmortem ultrasound vs 1.5T postmortem MRI for non-invasive perinatal autopsies

Objectives: To determine the diagnostic accuracy of postmortem magnetic resonance imaging (PM-MRI) and postmortem ultrasound (PM-US) for perinatal autopsy in the same patient cohort, and to determine whether PM-US can provide the same anatomical information as PM-MRI. Methods: In this prospective, 5-year (July 2014–July 2019) single-center study, we performed 1.5-T PM-MRI and PM-US in an unselected cohort of perinatal deaths. The diagnostic accuracies of both modalities were calculated, using autopsy as the reference standard. As a secondary objective, the concordance rates between the two imaging modalities for the overall main diagnosis and for five anatomical regions (brain, spine, thorax, heart and abdomen) were calculated. Results: During the study period, 136 cases underwent both PM-US and PM-MRI, of which 88 (64.7%) also underwent autopsy. There was no significant difference in the rates of concordance with autopsy between the two modalities for overall diagnosis (PM-US, 86.4% (95% CI, 77.7–92.0%) vs PM-MRI, 88.6% (95% CI, 80.3–93.7%)) or in the sensitivities and specificities for individual anatomical regions. There were more non-diagnostic PM-US than PM-MRI examinations for the brain (22.8% vs 3.7%) and heart (14.7% vs 5.1%). If an ‘imaging-only’ autopsy had been performed, PM-US would have achieved the same diagnosis as 1.5-T PM-MRI in 86.8% (95% CI, 80.0–91.5%) of cases, with the highest rates of agreement being for spine (99.3% (95% CI, 95.9–99.9%)) and cardiac (97.3% (95% CI, 92.4–99.1%)) findings and the lowest being for brain diagnoses (85.2% (95% CI, 76.9–90.8%)). Conclusion: Although there were fewer non-diagnostic cases using PM-MRI than for PM-US, the high concordance rate for overall diagnosis suggests that PM-US could be used for triaging cases when PM-MRI access is limited or unavailable

Three-dimensional versus two-dimensional postmortem ultrasound: feasibility in perinatal death investigation

Three- and four-dimensional US techniques in antenatal screening are commonplace, but they are not routinely used for perinatal postmortem US. In this technical innovation, we performed both two-dimensional (2-D) and three-dimensional (3-D) postmortem US on 11 foetuses (mean gestation: 23 weeks; range: 15–32 weeks) to determine whether there was any benefit in 3-D over conventional 2-D methods. In one case of osteogenesis imperfecta, both 2-D and 3-D US images were non-diagnostic because of small foetal size. Of the remaining 10 foetuses, 7 were normal at imaging and autopsy, and 3 had abnormalities detected on both 2-D and 3-D US. There were no false-positive diagnoses by 2-D or 3-D US. Whilst 3-D postmortem US was a feasible technique, it did not provide additional information over 2-D US. Routine 3-D postmortem US cannot therefore be routinely recommended based on our findings