Post-mortem perinatal imaging: what is the evidence?

Impact of non-invasive post-mortem micro-CT imaging on a fetal autopsy service: a single centre retrospective study

AIM

To evaluate the impact of a new, less-invasive micro-computed tomography (CT) service on autopsy service provision. We recorded parental consent, type of autopsy performed, autopsy reporting times and time taken for the body to be released from the mortuary.

MATERIALS AND METHODS

A retrospective, single-centre case series was conducted for all perinatal deaths since the introduction of our micro-CT service in 2016, with a detailed review of records extracted from 2019 and 2021. Fetal demographics (gestational age, weight), type of autopsy conducted, and the time taken from receiving the body to releasing the body and issuing a final report were recorded.

RESULTS

Micro-CT imaging uptake increased to over two hundred cases/year by 2021. Overall, invasive autopsies reduced from (45.8%, 196/428; 2019) to (32.1%, 125/390; 2021) with an equivalent rise in less-invasive autopsy from 54.2% (232/428;2019) to 67.9% (265/390;2019). Offering a micro-CT service resulted in an increase in consent to imaging-based autopsies from (76.9%, 329/428;2019) to (87.2%, 340/390;2021). Micro-CT has become the most common post-mortem imaging performed in our institution at 54.4% (212/251;2021), although the body preparation time from the tissue staining required has increased the time to provide an autopsy report to 17 days and release of the body to 18 days.

CONCLUSION

Our study shows that introducing a micro-CT post-mortem imaging service was associated with reduced use of conventional invasive procedures, despite a slight increase in turnaround times. Understanding these factors and continued improvements in micro-CT service delivery will help make this accessible to a wider population in the future.

Body weight-based iodinated contrast immersion timing for human fetal postmortem microfocus computed tomography

Objectives

The aim of this study was to evaluate the length of time required to achieve full iodination using potassium tri-iodide as a contrast agent, prior to human fetal postmortem microfocus computed tomography (micro-CT) imaging.

Methods

Prospective assessment of optimal contrast iodination was conducted across 157 human fetuses (postmortem weight range 2-298 g; gestational age range 12-37 weeks), following micro-CT imaging. Simple linear regression was conducted to analyse which fetal demographic factors could produce the most accurate estimate for optimal iodination time.

Results

Postmortem body weight (r2 = 0.6435) was better correlated with iodination time than gestational age (r2 = 0.1384), producing a line of best fit, y = [0.0304 × body weight (g)] - 2.2103. This can be simplified for clinical use whereby immersion time (days) = [0.03 × body weight (g)] - 2.2. Using this formula, for example, a 100-g fetus would take 5.2 days to reach optimal contrast enhancement.

Conclusions

The simplified equation can now be used to provide estimation times for fetal contrast preparation time prior to micro-CT imaging and can be used to manage service throughput and parental expectation for return of their fetus.

Advances in knowledge

A simple equation from empirical data can now be used to estimate preparation time for human fetal postmortem micro-CT imaging.

Micro-CT and high-field MRI for studying very early post-mortem human fetal anatomy at 8 weeks of gestation

OBJECTIVE

This study involved very early post-mortem (PM) examination of human fetal anatomy at 8 weeks of gestation (WG) using whole-body multimodal micro-imaging: micro-CT and high-field MRI (HF-MRI). We discuss the potential place of this imaging in early first-trimester virtual autopsy.

METHODS

We performed micro-CT after different contrast-bath protocols including diffusible iodine-based contrast-enhanced (dice) and HF-MRI with a 9.4 T machine with qualitative and quantitative evaluation and obtained histological sections.

RESULTS

Nine fetuses were included: the crown-rump length was 10-24 mm and corresponded to 7 and 9 WG according to the Robinson formula. The Carnegie stages were 17-21. Dice micro-CT and HF-MRI presented high signal to noise ratio, >5, according to the Rose criterion, and for allowed anatomical phenotyping in these specimens. Imaging did not alter the histology, allowing immunostaining and pathological examination.

CONCLUSION

PM non-destructive whole-body multimodal micro-imaging: dice micro-CT and HF-MRI allows for PM human fetal anatomy study as early as 8 WG. It paves the way to virtual autopsy in the very early first trimester. Obtaining a precision phenotype, even regarding miscarriage products, allows a reverse phenotyping to select variants of interest in genome-wide analysis, offering potential genetic counseling for bereaved parents.

Less-invasive autopsy for early pregnancy loss

Autopsy investigations provide valuable information regarding fetal death that can assist in the parental bereavement process, and influence future pregnancies, but conventional autopsy is often declined by parents because of its invasive approach. This has led to the development of less-invasive autopsy investigations based on imaging technology to provide a more accessible and acceptable choice for parents when investigating their loss. Whilst the development and use of more conventional clinical imaging techniques (radiographs, CT, MRI, US) are well described in the literature for fetuses over 20 weeks of gestational age, these investigations have limited diagnostic accuracy in imaging smaller fetuses. Techniques such as ultra-high-field MRI (>3T) and micro-focus computed tomography have been shown to have higher diagnostic accuracy whilst still being acceptable to parents. By further developing and increasing the availability of these more innovative imaging techniques, parents will be provided with a greater choice of acceptable options to investigate their loss, which may in turn increase their uptake. We provide a narrative review focussing on the development of high-resolution, non-invasive imaging techniques to evaluate early gestational pregnancy loss.

Current utilization of pediatric postmortem imaging in North America: a questionnaire-based survey

BACKGROUND

Postmortem imaging is used more widely as the number of conventional autopsies has decreased over the last several decades. It is widely accepted in Europe, Asia and Oceania, but there has been a delay in acceptance in North America. Education, scanning protocols, resourcing and clinical incentives are needed to support this emerging field.

OBJECTIVE

To determine the use of postmortem imaging and define perceived barriers to its implementation with the goal of expanding postmortem imaging in the United States and Canada.

MATERIALS AND METHODS

We sent an online survey to active members of the Society for Pediatric Radiology (SPR) addressing the use of postmortem imaging, indications, readers, practical aspects, anticipated barriers and potential solutions to more widespread use.

RESULTS

More than 50% of the 50 institutions that returned surveys used postmortem computed tomography; 24% used postmortem magnetic resonance imaging. Most postmortem imaging cases were read by radiologists. Fewer than 50% had formal correlation with autopsy results or an established relationship with the local medical examiner. Seven institutions reported reimbursement for postmortem imaging. Major barriers to postmortem imaging included lack of funding and lack of interest among clinicians. Funding and education were seen as important issues requiring attention.

CONCLUSION

While most responding institutions provide pediatric postmortem imaging, the modalities, protocols, reporting procedures and clinical correlation vary widely. A lack of funding and few opportunities for education are limiting factors. Attention to these issues along with active support from the SPR are seen as potential solutions to recognize the value and promote widespread acceptance of postmortem imaging.