Indications, advantages and limitations of perinatal postmortem imaging in clinical practice

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.

Fetal brain maceration score on postmortem magnetic resonance imaging vs. conventional autopsy

BACKGROUND

Postmortem fetal magnetic resonance imaging (MRI) has been on the rise since it was proven to be a good alternative to conventional autopsy. Since the fetal brain is sensitive to postmortem changes, extensive tissue fixation is required for macroscopic and microscopic assessment. Estimation of brain maceration on MRI, before autopsy, may optimize histopathological resources.

OBJECTIVE

The aim of the study is to develop an MRI-based postmortem fetal brain maceration score and to correlate it with brain maceration as assessed by autopsy.

MATERIALS AND METHODS

This retrospective single-center study includes 79 fetuses who had postmortem MRI followed by autopsy. Maceration was scored on MRI on a numerical severity scale, based on our brain-specific maceration score and the whole-body score of Montaldo. Additionally, maceration was scored on histopathology with a semiquantitative severity scale. Both the brain-specific and the whole-body maceration imaging scores were correlated with the histopathological maceration score. Intra- and interobserver agreements were tested for the brain-specific maceration score.

RESULTS

The proposed brain-specific maceration score correlates well with fetal brain maceration assessed by autopsy (τ = 0.690), compared to a poorer correlation of the whole-body method (τ = 0.452). The intra- and interobserver agreement was excellent (correlation coefficients of 0.943 and 0.864, respectively).

CONCLUSION

We present a brain-specific postmortem MRI maceration score that correlates well with the degree of fetal brain maceration seen at histopathological exam. The score is reliably reproduced by different observers with different experience.

The Practicality of Post-mortem Imaging in Prenatal, Perinatal, and Pediatric Cases

The essential role of the autopsy is seen in its contributions to medical care, scientific research, and family counseling. Major contributions are also noted in forensic pathology as a means to determine cause-of-death for legal and medical experts. However, autopsy acceptance rates are quite low due to an array of reasons including delayed burials, faith, and moral burdening. Thus, non-invasive post-mortem imaging strategies are becoming increasingly popular. The objective of this literature review is to evaluate the strengths and weaknesses of numerous post-mortem imaging modalities and consider their benefits over the traditional autopsy. The need for expertise in image interpretation for pediatric and perinatal cases is also discussed. A variety of publications, totaling 32 pieces, were selected from available literature on the basis of relevance. These articles studied various perinatal and pediatric post-mortem imaging strategies and their applications in clinical practice. Key strategies include post-mortem MRI, post-mortem CT, fetal post-mortem sonography, post-mortem computed tomographic angiography, and three-dimensional surface scanning. There is a general consensus that no standard model for post-mortem imaging currently exists in the United States and European countries. Amongst the imaging modems studied, post-mortem MRI has been acknowledged to show the greatest promise in diagnostic accuracy for fetal age groups. Most studies demonstrated that post-mortem CT had limited use for autopsy. Post-mortem imaging strategies for autopsy have high potential given their minimal invasiveness and increasing popularity. Furthermore, it is vital to crafting a global standard procedure for post-mortem imaging for prenatal, perinatal, and pediatric cases to better understand the cause of death, decomposition factors, and effects in-utero, and to provide an alternative to traditional autopsy.

Diagnostic value of virtual autopsy using pm-MRI at 3T on malformed second trimester fetuses vs classic autopsy

Objective

To determine the diagnostic value of virtual autopsy using post mortem-MRI (pm-MRI) at 3Tesla (T) compared to classic autopsy for the confirmation of fetal structural anomalies and secondly to establish which cases of termination of pregnancy would benefit mostly from a virtual autopsy.

Methods

In each of 32 fetuses included in the study, 32 anatomical structures were assessed, after termination of pregnancy in the second trimester. All cases were evaluated by prenatal ultrasonography, virtual autopsy and classic autopsy, and then divided into four groups: Cerebral Group, Cardiac Group, Renal Group and Other Group (miscellaneous group). The concordance of virtual autopsy with classic autopsy was calculated overall and for each group and each structural item. Also, the concordance between the two methods was assessed using a diagnostic error score (DgE_score), calculated as the absolute value of the difference between the number of malformations detected by classic autopsy per case (CA score) and the number of malformations detected at virtual autopsy per case (VA score).

Results

Overall virtual autopsy demonstrated a diagnostic sensitivity (Se) compared to classic autopsy of 67.33% [95% CI 57.28–76.33], with a specificity (Sp) of 98.37% [95% CI 97.33–99.09], a positive predictive value (PPV) of 81.93% [95% CI 71.95–89.52], a negative predictive value (NPV) of 96.49% [95% CI 95.11–97.57] achieving a diagnostic accuracy of 95.31% [95% CI 93.83–96.52]. Overall, no statistic significant correlation was demonstrated between DgE_score and the gestational age of the fetuses or between DgE_score and the weight of the fetuses, but a significant correlation was revealed between the virtual autopsy and classic autopsy score. The diagnostic utility of virtual autopsy using pm-MRI at 3 T as compared to classic autopsy for each category of termination of pregnancy revealed in the Cerebral Group a Se of 80.00% [95% CI 28.36–99.49], with a 96.30% [95% CI 81.03–99.91], a PPV of 80.00% [95% CI 35.75–96.64] a NPV of 96.30% [95% CI 81.81–99.34], with a diagnostic accuracy of 93.75% [95% CI 79.19% to 99.23] and a Cohen’s Kappa coefficient of 0.76 [95% CI 0.4494–1.0765]; in the Renal Group a Se and Sp of 100%, but in the Cardiac Group the Se was only 60.00% [95% CI 26.24–87.84], Sp 75% [95% CI 34.91–96.81], the PPV 75.00% [95% CI 44.92–91.69], NPV 60% [95% CI 38.87–77.96], with a diagnostic accuracy of 66.67% [95% CI 40.99–86.66] and a Cohen’s Kappa coefficient of 0.32 [95% CI -0.07–0.76].

Conclusions

The results support virtual autopsy using pm-MRI at 3T as a reliable alternative to classic autopsy for the non-forensic analysis of second trimester fetuses. Analyzing the diagnostic utility of virtual autopsy using pm-MRI at 3 T for the confirmation of prenatal ultrasound findings in second trimester fetuses as compared to classic autopsy, the best results were obtained in the Cerebral and Renal Group. Reserved results were found in the Cardiac Group. Therefore, for the pregnancies with termination of pregnancy for cerebral or renal abnormalities, virtual autopsy by pm-MRI at 3T can be taken into consideration as a first-line investigation to confirm the prenatal findings.

Navigating the perils and pitfalls of pediatric forensic postmortem imaging in the United States

Postmortem CT is widely used in the general adult and military populations. It is used extensively in pediatric death investigations in Europe and Asia, but distinctive challenges are encountered when launching a postmortem imaging program in the United States. We describe the issues we have encountered specific to establishing a pediatric postmortem imaging service in this country and propose potential solutions.

Human fetal whole-body postmortem microfocus computed tomographic imaging

Perinatal autopsy is the standard method for investigating fetal death; however, it requires dissection of the fetus. Human fetal microfocus computed tomography (micro-CT) provides a generally more acceptable and less invasive imaging alternative for bereaved parents to determine the cause of early pregnancy loss compared with conventional autopsy techniques. In this protocol, we describe the four main stages required to image fetuses using micro-CT. Preparation of the fetus includes staining with the contrast agent potassium triiodide and takes 3-19 d, depending on the size of the fetus and the time taken to obtain consent for the procedure. Setup for imaging requires appropriate positioning of the fetus and takes 1 h. The actual imaging takes, on average, 2 h 40 min and involves initial test scans followed by high-definition diagnostic scans. Postimaging, 3 d are required to postprocess the fetus, including removal of the stain, and also to undertake artifact recognition and data transfer. This procedure produces high-resolution isotropic datasets, allowing for radio-pathological interpretations to be made and long-term digital archiving for re-review and data sharing, where required. The protocol can be undertaken following appropriate training, which includes both the use of micro-CT techniques and handling of postmortem tissue.

Multiparametric mapping in post-mortem perinatal MRI: a feasibility study

OBJECTIVES

To demonstrate feasibility of a 3 T multiparametric mapping (MPM) quantitative pipeline for perinatal post-mortem MR (PMMR) imaging.

METHODS

Whole body quantitative PMMR imaging was acquired in four cases, mean gestational age 34 weeks, range (29-38 weeks) on a 3 T Siemens Prisma scanner. A multicontrast protocol yielded proton density, T₁ and magnetic transfer (MT) weighted multi-echo images obtained from variable flip angle (FA) 3D fast low angle single-shot (FLASH) acquisitions, radiofrequency transmit field map and one B₀ field map alongside four MT weighted acquisitions with saturation pulses of 180, 220, 260 and 300 degrees were acquired, all at 1 mm isotropic resolution.

RESULTS

Whole body MPM was achievable in all four foetuses, with R₁, R₂*, PD and MT maps reconstructed from a single protocol. Multiparametric maps were of high quality and show good tissue contrast, especially the MT maps.

CONCLUSION

MPM is a feasible technique in a perinatal post-mortem setting, which may allow quantification of post-mortem change, prior to being evaluated in a clinical setting.

ADVANCES IN KNOWLEDGE

We have shown that the MPM sequence is feasible in PMMR imaging and shown the potential of MT imaging in this setting.

Intrauterine versus post-mortem magnetic resonance in second trimester termination of pregnancy for central nervous system abnormalities

OBJECTIVE

To evaluate if limiting factors of intrauterine magnetic resonance imaging (iuMRI) performed in the early second trimester of pregnancy (19-23 weeks) affect its accuracy in comparison to post-mortem MRI (pmMRI) in fetuses that underwent termination of pregnancy (TOP) for central nervous system (CNS) defects.

STUDY DESIGN

This is a secondary analysis of a 10 years prospective observational study. Cases of TOP < 23 weeks for CNS malformation that had undergone neurosonography (NSG), iuMRI, pmMRI and autopsy were included. The agreement between iuMRI and pmMRI was calculated. The autopsy represented the gold-standard.

RESULTS

Overall, 143 TOPs for fetal congenital anomaly underwent the post-mortem diagnostic protocol. Of these, 31 cases underwent iuMRI and pmMRI for CNS abnormality. Three cases were excluded due to brain autolysis at autopsy. Corpus callosum defects were the most represented (16/28; 57 %). In only one case of posterior fossa defect, pmMRI identified the presence of vermian hypoplasia not diagnosed at iuMRI. In 2 cases (7%), iuMRI added clinically relevant additional findings to NSG, that were posteriorly confirmed by pmMRI.

CONCLUSIONS

The study shows that, at 19-23 weeks and for CNS defects, limiting factors that might influence the performance of iuMRI have little influence on iuMRI accuracy. This finding is particularly important for professionals who work in countries with legal bound for TOP in the early second trimester.

Maceration determines diagnostic yield of fetal and neonatal whole body post-mortem ultrasound

OBJECTIVES

To determine factors in nondiagnostic fetal and neonatal post-mortem ultrasound (PMUS) examinations.

METHODS

All fetal and neonatal PMUS examinations were included over a 5-year study period (2014-2019). Nondiagnostic image quality by body parts (brain, spine, thorax, cardiac, and abdomen) was recorded and correlated with patient variables. Descriptive statistics and logistic regression analyses were performed to identify significant factors for nondiagnostic studies.

RESULTS

Two hundred sixty-five PMUS examinations were included, with median gestational age of 22 weeks (12-42 wk), post-mortem weight of 363 g (16-4033 g), and post-mortem interval of 8 days (0-39 d). Diagnostic imaging quality was achieved for 178/265 (67.2%) studies. It was high for abdominal (263/265, 99.2%), thoracic (264/265, 99.6%), and spine (265/265, 100%) but lower for brain (210/265, 79.2%) and cardiac imaging (213/265, 80.4%). Maceration was the best overall predictor for nondiagnostic imaging quality (P < .0001). Post-mortem fetal weight was positively associated with cardiac (P = .0133) and negatively associated with brain imaging quality (P = .0002). Post-mortem interval was not a significant predictor.

CONCLUSIONS

Fetal maceration was the best predictor for nondiagnostic PMUS, particularly for brain and heart. Fetuses with marked maceration and suspected cardiac or brain anomalies should be prioritised for post-mortem MRI.

"The communication and support from the health professional is incredibly important": A qualitative study exploring the processes and practices that support parental decision-making about postmortem examination

Background

Consent rates for postmortem (PM) examination in the perinatal and paediatric setting have dropped significantly in the United Kingdom, the United States, and the Western Europe. We explored the factors that act as facilitators or barriers to consent and identified processes and practices that support parental decision‐making.

Methods

A qualitative study conducted with bereaved parents, parent advocates, and health care professionals in the United Kingdom. Analysis was conducted on 439 free‐tect comments within a cross‐sectional survey, interviews with a subset of 20 survey respondents and 25 health professionals, and a focus group with five parent advocates.

Results

Three broad parental decision‐making groups were identified: 1, “Not open to postmortem examination”; 2, “Consent regardless of concerns”; and 3, “Initially undecided.” Decisional drivers that were particularly important for this “undecided” group were “the initial approach,” “adjustment and deliberation,” “detailed discussion about the procedure,” and “formal consent.” The way in which these were managed by health care staff significantly impacted whether those parents' consented to PM, particularly for those who are ambivalent about the procedure.

Conclusions

We propose a set of recommendations to improve the way PM counselling and consent is managed. Adopting such measures is likely to lead to improved family experience and more consistent and high‐quality discussion regarding PM.

What's already known about this topic?

There has been a significant decline in uptake of paediatric post mortem, despite evidence that it provides clinically useful data in between 22% and 76% of cases.

What does this study add?

This study identifies key actions by health care staff that are highly influential in whether or not parents' consent to the postmortem procedure. Recommendations for practice are also provided.

Perinatal post-mortem ultrasound (PMUS): radiological-pathological correlation

There has been an increasing demand and interest in post-mortem imaging techniques, either as an adjunct or replacement for the conventional invasive autopsy. Post-mortem ultrasound (PMUS) is easily accessible and more affordable than other cross-sectional imaging modalities and allows visualisation of normal anatomical structures of the brain, thorax and abdomen in perinatal cases. The lack of aeration of post-mortem foetal lungs provides a good sonographic window for assessment of the heart and normal pulmonary lobulation, in contrast to live neonates.In a previous article within this journal, we published a practical approach to conducting a comprehensive PMUS examination. This covered the basic principles behind why post-mortem imaging is performed, helpful techniques for obtaining optimal PMUS images, and the expected normal post-mortem changes seen in perinatal deaths. In this article, we build upon this by focusing on commonly encountered pathologies on PMUS and compare these to autopsy and other post-mortem imaging modalities.

Pediatric postmortem computed tomography: initial experience at a children's hospital in the United States

Postmortem CT might provide valuable information in determining the cause of death and understanding disease processes, particularly when combined with traditional autopsy. Pediatric applications of postmortem imaging represent a new and rapidly growing field. We describe our experience in establishing a pediatric postmortem CT program and present a discussion of the distinct challenges in developing this type of program in the United States of America, where forensic practice varies from other countries. We give a brief overview of recent literature along with the common imaging findings on postmortem CT that can simulate antemortem pathology.

Finite element modelling of the developing infant femur using paired CT and MRI scans

Bone finite element (FE) studies based on infant post-mortem computed tomography (CT) examinations are being developed to provide quantitative information to assist the differentiation between accidental and inflicted injury, and unsuspected underlying disease. As the growing skeleton contains non-ossified cartilaginous regions at the epiphyses, which are not well characterised on CT examinations, it is difficult to evaluate the mechanical behaviour of the developing whole bone. This study made use of paired paediatric post mortem femoral CT and magnetic resonance imaging (MRI) examinations at two different stages of development (4 and 7 months) to provide anatomical and constitutive information for both hard and soft tissues. The work aimed to evaluate the effect of epiphyseal ossification on the propensity to shaft fractures in infants. The outcomes suggest that the failure load of the femoral diaphysis in the models incorporating the non-ossified epiphysis is within the range of bone-only FE models. There may however be an effect on the metaphysis. Confirmation of these findings is required in a larger cohort of children.

Automated data extraction and report analysis in computer-aided radiology audit: practice implications from post-mortem paediatric imaging

AIM

To determine local departmental adherence to the paediatric post-mortem magnetic resonance imaging (MRI) protocols, using a customised automated computational approach.

MATERIALS AND METHODS

A retrospective review of 460 whole-body post-mortem MRI examinations performed at Great Ormond Street Hospital for Children over a 5.5-year period was assessed for adherence to a full or abbreviated imaging sequence protocol. A simple computer program was developed to batch process DICOM (digital imaging and communications in medicine) files, extracting imaging sequence details, followed by natural language processing (NLP) of authorised reports to automate information extraction of diagnostic image quality.

RESULTS

The program was able to extract study parameters from the entire dataset (approximately 80 GB of data) in a few hours, and retrieve information on diagnostic image quality using NLP with an overall diagnostic accuracy for data extraction of 96.7% (445/460, 95% confidence interval [CI]: 94.7-98%). The full imaging protocol was adhered to in 305/460 (66.3%) cases, and an abbreviated protocol in 140/460 (30.4%) cases. Overall, 423/460 (91.9%) of studies were of diagnostic quality. These included 298/305 (97.7%) of the full protocol, 111/140 (79.3%) of the abbreviated protocol. In only five cases were the examinations non-diagnostic for all body systems, all of whom weighed <100 g (24.7-72 g) and imaged using the abbreviated protocol.

CONCLUSION

The present study demonstrated a successful application of an automated approach for data collection for audit and quality assessment purposes using paediatric post-mortem imaging as a specific example. Re-audit of these data following change implementation will be straightforward now that the automated workflow is clearly established.

Evaluation of septal insertion of atrioventricular valves in fetuses by postmortem 4.7 Tesla cardiac MRI: A feasibility study

PURPOSE

The purpose of this study was to compare non-invasive high-spatial-resolution postmortem cardiac magnetic resonance imaging (MRI) and autopsy findings for evaluating the septal insertion of atrioventricular valves in fetuses.

MATERIALS AND METHODS

Five fetal heart specimens including two normal hearts, one heart with complete atrioventricular septal defect (AVSD) and two hearts with linear insertion of atrioventricular valves (LIAVV; gestational age 17 to 34 weeks) were studied with cardiac MRI using a 4.7 T MRI scanner without sample preparation. Three (3D) and two-dimensional (2D) turbo-RARE (rapid imaging with refocused echoes) sequences in four-chamber and left-ventricular long-axis planes were obtained with a minimal isotropic/in-plane resolution of 156μm. Nonparametric tests were performed to compare the distance between insertions of medial leaflets of the atrioventricular valves and the inlet/outlet distance ratio between MRI and autopsy findings in normal, complete AVSD and with linear insertion of atrioventricular valves (LIAVV) fetal hearts.

RESULTS

Despite apparent differences between LIAVV/normal hearts, no significant differences were found between differential insertion of medial leaflets and inlet/outlet distance ratios with both techniques. Very good to excellent reliability between both techniques was found for differential insertion (ICC: 87.2%; 95% CI: -21.7%, 99.1%) (P=0.963) and inlet/outlet distance ratio (ICC 98.3%; 95%CI: 85.2%, 99.8%) (P=0.537) measurements.

CONCLUSION

Postmortem cardiac MRI could replace autopsy for assessing normal or abnormal septal insertion of atrioventricular valves in fetuses without requiring specific preparation of the heart.

Flexible proton density (PD) mapping using multi-contrast variable flip angle (VFA) data

Quantitative proton density (PD) maps measure the amount of free water, which is important for non-invasive tissue characterization in pathology and across lifespan. PD mapping requires the estimation and subsequent removal of factors influencing the signal intensity other than PD. These factors include the T1, T2* relaxation effects, transmit field inhomogeneities, receiver coil sensitivity profile (RP) and the spatially invariant factor that is required to scale the data. While the transmit field can be reliably measured, the RP estimation is usually based on image post-processing techniques due to limitations of its measurement at magnetic fields higher than 1.5 T. The post-processing methods are based on unified bias-field/tissue segmentation, fitting the sensitivity profile from images obtained with different coils, or on the linear relationship between T1 and PD. The scaling factor is derived from the signal within a specific tissue compartment or reference object. However, these approaches for calculating the RP and scaling factor have limitations particularly in severe pathology or over a wide age range, restricting their application. We propose a new approach for PD mapping based on a multi-contrast variable flip angle acquisition protocol and a data-driven estimation method for the RP correction and map scaling. By combining all the multi-contrast data acquired at different echo times, we are able to fully correct the MRI signal for T2* relaxation effects and to decrease the variance and the entropy of PD values within tissue class of the final map. The RP is determined from the corrected data applying a non-parametric bias estimation, and the scaling factor is based on the median intensity of an external calibration object. Finally, we compare the signal intensity and homogeneity of the multi-contrast PD map with the well-established effective PD (PD*) mapping, for which the RP is based on concurrent bias field estimation and tissue classification, and the scaling factor is estimated from the mean white matter signal. The multi-contrast PD values homogeneity and accuracy within the cerebrospinal fluid (CSF) and deep brain structures are increased beyond that obtained using PD* maps. We demonstrate that the multi-contrast RP approach is insensitive to anatomical or a priori tissue information by applying it in a patient with extensive brain abnormalities and for whole body PD mapping in post-mortem foetal imaging.

High resolution isotropic diffusion imaging in post-mortem neonates: a feasibility study

OBJECTIVE:

To investigate the potential of advanced diffusion weighted imaging (DWI) in post-mortem MRI (PMMR) at 3T.

METHODS:

We acquired PMMR brain and body imaging in 12 neonates, mean gestational age 33.4 weeks (range 29-37 weeks) at 3T and 1.5T. Head and body diffusion imaging at 1.5T consisted of bipolar diffusion encoding and single-shot spin-echo echo-planar imaging (SE-EPI) for acquisition (echo time (TE) 96 ms; repetition time (TR) 2700 ms; voxel size 1.8 x 1.8 mm in-plane with slice thickness 5 mm; b-values of 500 and 1000 s/mm² applied in three orthogonal directions; total acquisition time 2:12). A whole-body 3T diffusion imaging protocol using monopolar diffusion encoding and simultaneous multislice EPI acquisition with gradients applied in 12 uniformly distributed directions was obtained (TE 53.4 ms; TR 5600 ms; 1.8 mm isotropic; multiband factor 2; b-values of 250, 750, 1250 and 1750 s/mm²; acquisition time 2:09 for a single b-value).

RESULTS:

There was significant improvement in image quality in multiband, multislice diffusion PMMR protocol. On visual assessment of image quality, 1.5T DWI scored poorly (mean 2.4 SD ± 0.47), and all 3T b-values individually scored significantly higher (p < 0.001) apart from b = 250 s/mm² which was not significantly different.

CONCLUSION:

Recent advances in diffusion sequences and hardware utilising higher field strengths and gradient performance allows whole-body diffusion PMMR imaging at high resolution with improved image quality compared to the current clinical approach.

ADVANCES IN KNOWLEDGE:

We have demonstrated feasibility of a multislice, multiband quantitative diffusion imaging sequence in the perinatal post-mortem setting. This will allow more detailed and quantitative clinical PMMR investigations using diffusion MRI in the future.

Postmortem fetal magnetic resonance imaging: where do we stand?

Abstract

Postmortem fetal magnetic resonance imaging (PMFMRI) is increasingly used thanks to its good overall concordance with histology paralleling the rising incidence of parental refusal of autopsy. The technique could become a routine clinical examination but it needs to be standardized and conducted by trained radiologists. Such radiologists should be aware of not only the (congenital and acquired) anomalies that can involve the fetus, but also of the “physiological” postmortem changes. In this article, we intend to focus on the contribution of PMFMRI based on the existing literature and on our own experience, as we presently perform the technique routinely in our clinical practice.

Key Points

• Concordance rates between PMFMRI and autopsy are high for detecting fetal pathologies.

• PMFMRI is more acceptable for parents than traditional autopsy.

• PMFMRI is becoming widely used as a part of the postmortem investigations.

• A dedicated radiologist needs to learn to interpret correctly a PMFMRI.

• PMFMRI can be easily realized in daily clinical practice.

Pulmonary embolus as cause of death in an adolescent: demonstration on postmortem CT

Computed tomography (CT) is widely accepted in adult forensic death investigations (determination of cause and manner of death) but is only beginning to play a larger role in the cause of death determination in infants and children. We present a case of an adolescent with nephrotic syndrome who sustained cardiac arrest and died in the emergency department. A postmortem CT was requested by the state Office of the Medical Examiner as part of the medicolegal death investigation. Postmortem CT showed a saddle pulmonary embolus that was confirmed on conventional autopsy, demonstrating a natural manner of death.

Interventions for investigating and identifying the causes of stillbirth

BACKGROUND

Identification of the causes of stillbirth is critical to the primary prevention of stillbirth and to the provision of optimal care in subsequent pregnancies. A wide variety of investigations are available, but there is currently no consensus on the optimal approach. Given their cost and potential to add further emotional burden to parents, there is a need to systematically assess the effect of these interventions on outcomes for parents, including psychosocial outcomes, economic costs, and on rates of diagnosis of the causes of stillbirth.

OBJECTIVES

To assess the effect of different tests, protocols or guidelines for investigating and identifying the causes of stillbirth on outcomes for parents, including psychosocial outcomes, economic costs, and rates of diagnosis of the causes of stillbirth.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (31 August 2017), ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (15 May 2017).

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs), quasi-RCTs, and cluster-RCTs. We planned to include studies published as abstract only, provided there was sufficient information to allow us to assess study eligibility. We planned to exclude cross-over trials.Participants included parents (including mothers, fathers, and partners) who had experienced a stillbirth of 20 weeks' gestation or greater.This review focused on interventions for investigating and identifying the causes of stillbirth. Such interventions are likely to be diverse, but could include:* review of maternal and family history, and current pregnancy and birth history;* clinical history of present illness;* maternal investigations (such as ultrasound, amniocentesis, antibody screening, etc.);* examination of the stillborn baby (including full autopsy, partial autopsy or noninvasive components, such as magnetic resonance imaging (MRI), computerised tomography (CT) scanning, and radiography);* umbilical cord examination;* placental examination including histopathology (microscopic examination of placental tissue); and* verbal autopsy (interviews with care providers and support people to ascertain causes, without examination of the baby).We planned to include trials assessing any test, protocol or guideline (or combinations of tests/protocols/guidelines) for investigating the causes of stillbirth, compared with the absence of a test, protocol or guideline, or usual care (further details are presented in the Background, see Description of the intervention).We also planned to include trials comparing any test, protocol or guideline (or combinations of tests/protocols/guidelines) for investigating the causes of stillbirth with another, for example, the use of a limited investigation protocol compared with a comprehensive investigation protocol.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial eligibility independently.

MAIN RESULTS

We excluded five studies that were not RCTs. There were no eligible trials for inclusion in this review.

AUTHORS' CONCLUSIONS

There is currently a lack of RCT evidence regarding the effectiveness of interventions for investigating and identifying the causes of stillbirth. Seeking to determine the causes of stillbirth is an essential component of quality maternity care, but it remains unclear what impact these interventions have on the psychosocial outcomes of parents and families, the rates of diagnosis of the causes of stillbirth, and the care and management of subsequent pregnancies following stillbirth. Due to the absence of trials, this review is unable to inform clinical practice regarding the investigation of stillbirths, and the specific investigations that would determine the causes.Future RCTs addressing this research question would be beneficial, but the settings in which the trials take place, and their design, need to be given careful consideration. Trials need to be conducted with the utmost care and consideration for the needs, concerns, and values of parents and families. Assessment of longer-term psychosocial variables, economic costs to health services, and effects on subsequent pregnancy care and outcomes should also be considered in any future trials.

Diagnosis of congenital abnormalities with post-mortem ultrasound in perinatal death

PURPOSE

To determine the sensitivity and specificity of post-mortem ultrasound in the diagnosis of major congenital abnormalities of fetuses using conventional autopsy as the standard of reference.

MATERIAL AND METHODS

All fetuses coming from terminations of pregnancy or intrauterine fetal deaths in a single institution were included. A total of 75 fetuses were included during the study period. The results of post-mortem ultrasound examinations were compared to those of conventional autopsy that served as standard of reference.

RESULTS

Gestational age of the fetuses ranged from 15 to 38 weeks gestation. A complete post-mortem ultrasound assessment was possible in all fetuses. Regarding detection of brain abnormalities, post-mortem ultrasound had a sensitivity of 81.5% or 4/5 (95% CI: 63.3-91.8%), and a specificity of 97.9% (95% CI: 89.1-99.6%). Specificities for the diagnosis of thoracic, cardiac, urinary tract, spinal and bone abnormalities were 100%.

CONCLUSION

Post-mortem ultrasound shows high sensitivity and specificity for the diagnosis of congenital structural abnormalities as compared to conventional autopsy, with the exception of congenital cardiac diseases.

Learning effect on perinatal post-mortem magnetic resonance imaging reporting: single reporter diagnostic accuracy of 200 cases

OBJECTIVE

The objective of the study is to compare diagnostic accuracy of perinatal post-mortem magnetic resonance (PMMR) imaging against conventional autopsy, when reported by a single-blinded observer for all organ systems following a period of initial experience.

METHODS

We compared pre-autopsy PMMR with conventional autopsy for the detection of (1) major pathological abnormalities related to the cause of death and (2) all diagnostic findings in five different body organ systems. PMMR was reported blinded to autopsy findings.

RESULTS

In 201 cases, 123/146 (84.2%) of major abnormalities were identified by PMMR. Overall diagnostic accuracy of PMMR was 89.6% [95% confidence interval (CI): 84.3, 93.2%] across all cases, with high concordance 91.8% (95% CI: 89.9, 93.4%) across most organ systems. Our study showed higher concordance than single reporter statistics previously reported in neurological [92.2% vs 73.8%; diff 18.4% (95% CI: 11.0, 25.4%) p < 0.01] and thoracic systems [93.7% vs 81.2%; diff 12.5% (95% CI: 6.3, 18.4%) p < 0.01] and slightly better overall [91.8% vs 87.1%; diff 4.7% (95% CI: 2.1, 7.3%) p < 0.01].

CONCLUSION

The PMMR examinations can be reliably reported by a single radiologist, following a period of experience and training with this specific modality, with high-diagnostic accuracy for all organ systems. © 2017 John Wiley & Sons, Ltd.

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.

ESPR postmortem imaging task force: where we begin

A new task force on postmortem imaging was established at the annual meeting of the European Society of Paediatric Radiology (ESPR) in Graz, Austria, in 2015. The postmortem task force is separate from the child abuse task force as it covers all aspects of fetal, neonatal and non-forensic postmortem imaging. The main focus of the task force is the guidance and standardization of non-radiographic postmortem imaging, particularly postmortem CT and postmortem MRI. This manuscript outlines the starting point of the task force, with a mission statement, outline of current experience, and short- and long-term goals.

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.

Comparison of diagnostic performance for perinatal and paediatric post-mortem imaging: CT versus MRI

OBJECTIVES

To compare the diagnostic yield of whole-body post-mortem computed tomography (PMCT) imaging to post-mortem magnetic resonance (PMMR) imaging in a prospective study of fetuses and children.

METHODS

We compared PMCT and PMMR to conventional autopsy as the gold standard for the detection of (a) major pathological abnormalities related to the cause of death and (b) all diagnostic findings in five different body organ systems.

RESULTS

Eighty two cases (53 fetuses and 29 children) underwent PMCT and PMMR prior to autopsy, at which 55 major abnormalities were identified. Significantly more PMCT than PMMR examinations were non-diagnostic (18/82 vs. 4/82; 21.9 % vs. 4.9 %, diff 17.1 % (95 % CI 6.7, 27.6; p < 0.05)). PMMR gave an accurate diagnosis in 24/55 (43.64 %; 95 % CI 31.37, 56.73 %) compared to 18/55 PMCT (32.73 %; 95 % CI 21.81, 45.90). PMCT was particularly poor in fetuses <24 weeks, with 28.6 % (8.1, 46.4 %) more non-diagnostic scans. Where both PMCT and PMMR were diagnostic, PMMR gave slightly higher diagnostic accuracy than PMCT (62.8 % vs. 59.4 %).

CONCLUSION

Unenhanced PMCT has limited value in detection of major pathology primarily because of poor-quality, non-diagnostic fetal images. On this basis, PMMR should be the modality of choice for non-invasive PM imaging in fetuses and children.

KEY POINTS

• Overall 17.1 % more PMCT examinations than PMMR were non-diagnostic • 28.6 % more PMCT were non-diagnostic than PMMR in fetuses <24 weeks • PMMR detected almost a third more pathological abnormalities than PMCT • PMMR gave slightly higher diagnostic accuracy when both were diagnostic.

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

OBJECTIVE

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.

MATERIALS AND METHODS

We retrospectively assessed PMMR imaging features of a group of late foetal terminations following fetocide and stillbirths (without witnessed breathing) and early infant deaths (breathed spontaneously before death). PMMR images were reviewed for evidence of lung aeration and other features, blinded to the clinical and autopsy data.

RESULTS

Nineteen infant deaths (mean age 3.0 ± 6.5 post-natal weeks) and 23 foetal terminations or stillbirths (mean age 32.6 ± 10.2-week gestation) were compared. Subjective appearances of lung aeration on PMMR were the best indicator of live birth, with a sensitivity of 89.5% (95% confidence interval 68.6, 97.1%) and specificity of 95.6% (79.0, 99.2%) and positive and negative predictive values of 94.4% and 91.7%, respectively.

CONCLUSIONS

Lung aeration on PMMR appears to have high overall accuracy for confirmation of live birth versus intrauterine foetal death but now requires validating in a larger cohort of perinatal deaths.

The future of pediatric and perinatal postmortem imaging

The field and applications of postmortem imaging are exponentially growing. Its potential to identify the cause of death in trauma and ballistic cases is now properly documented, as well as its use in drug mule identification. In pediatric and perinatal practice, large significant series are less available, except for MRI and central nervous system analysis where scientific evidence is now robust. In this review, after a short historical review and analysis of current problems and challenges, we will try to depict the way we see the future of this subspecialty of postmortem cross-sectional imaging, including all specific situations: terminations of pregnancy, intrauterine death, sudden unexpected infant death and identification issues.

Diffusion-weighted perinatal postmortem magnetic resonance imaging as a marker of postmortem interval

Objective

To evaluate perinatal body organ apparent diffusion coefficient (ADC) values at postmortem magnetic resonance imaging (PMMR) in order to evaluate postmortem changes.

Methods

Postmortem diffusion-weighted imaging (DWI) of the thorax and abdomen were performed with diffusion gradient values b = 0, 500, and 1000 s/mm² on 15 foetal and childhood cases (mean 33.3 ± 7.8 weeks gestation) compared to 44 live infants (mean age 75.5 ± 53.4 days). Mean ADC values were calculated from regions of interest (ROIs) for the lungs, liver, spleen and renal cortex, compared to normative live infantile body ADC values of similar gestational age.

Results

Mean ADC values were significantly lower in postmortem cases than in normal controls for liver (0.88 10^-3 mm²/s ± SD 0.39 vs. 1.13 ± 0.13; p < 0.05) and renal cortex (0.85 ± 0.26 vs. 1.19 ± 0.13; p < 0.05) but not spleen or muscle. Mean lung ADC values were significantly higher than normal controls (1.06 ± 0.18 vs. 0 ± 0; p < 0.001), and there was a significant correlation between postmortem interval and lung ADC (R² = 0.55).

Conclusion

Lung PMMR ADC values are related to postmortem interval, making them a potential marker of time since death. Further research is needed to understand the organ-specific changes which occur in the postmortem period.

Key Points

• Liver and spleen PM ADC values were lower than controls.

• Lung ADC changes correlate with PM interval.

• These findings may be useful in medicolegal cases.