Human fetal whole-body postmortem microfocus computed tomographic imaging

Quantitative microCT imaging of a whole equine placenta and its blood vessel network

Placental structure is linked to function across morphological scales. In the placenta, changes to gross anatomy, such as surface area, volume, or blood vessel arrangement, are associated with suboptimal physiological outcomes. However, quantifying each of these metrics requires different laborious semi-quantitative methods. Here, we demonstrate how, with minimal sample preparation, whole-organ computed microtomography (microCT) can be used to calculate gross morphometry of the equine placenta and a range of additional metrics, including branching morphometry of placental vasculature, non-destructively from a single dataset. Our approach can be applied to quantify the gross structure of any large mammalian placenta.

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.

A high-throughput 3D X-ray histology facility for biomedical research and preclinical applications

Background

The University of Southampton, in collaboration with the University Hospital Southampton (UHS) NHS Foundation Trust and industrial partners, has been at the forefront of developing three-dimensional (3D) imaging workflows using X-ray microfocus computed tomography (μCT) -based technology. This article presents the outcomes of these endeavours and highlights the distinctive characteristics of a μCT facility tailored explicitly for 3D X-ray Histology, with a primary focus on applications in biomedical research and preclinical and clinical studies.

Methods

The UHS houses a unique 3D X-ray Histology (XRH) facility, offering a range of services to national and international clients. The facility employs specialised μCT equipment explicitly designed for histology applications, allowing whole-block XRH imaging of formalin-fixed and paraffin-embedded tissue specimens. It also enables correlative imaging by combining μCT imaging with other microscopy techniques, such as immunohistochemistry (IHC) and serial block-face scanning electron microscopy, as well as data visualisation, image quantification, and bespoke analysis.

Results

Over the past seven years, the XRH facility has successfully completed over 120 projects in collaboration with researchers from 60 affiliations, resulting in numerous published manuscripts and conference proceedings. The facility has streamlined the μCT imaging process, improving productivity and enabling efficient acquisition of 3D datasets.

Discussion & Conclusions

The 3D X-ray Histology (XRH) facility at UHS is a pioneering platform in the field of histology and biomedical imaging. To the best of our knowledge, it stands out as the world's first dedicated XRH facility, encompassing every aspect of the imaging process, from user support to data generation, analysis, training, archiving, and metadata generation. This article serves as a comprehensive guide for establishing similar XRH facilities, covering key aspects of facility setup and operation. Researchers and institutions interested in developing state-of-the-art histology and imaging facilities can utilise this resource to explore new frontiers in their research and discoveries.

An integrated single-cell analysis of human adrenal cortex development

The adrenal glands synthesize and release essential steroid hormones such as cortisol and aldosterone, but many aspects of human adrenal gland development are not well understood. Here, we combined single-cell and bulk RNA sequencing, spatial transcriptomics, IHC, and micro-focus computed tomography to investigate key aspects of adrenal development in the first 20 weeks of gestation. We demonstrate rapid adrenal growth and vascularization, with more cell division in the outer definitive zone (DZ). Steroidogenic pathways favored androgen synthesis in the central fetal zone, but DZ capacity to synthesize cortisol and aldosterone developed with time. Core transcriptional regulators were identified, with localized expression of HOPX (also known as Hop homeobox/homeobox-only protein) in the DZ. Potential ligand-receptor interactions between mesenchyme and adrenal cortex were seen (e.g., RSPO3/LGR4). Growth-promoting imprinted genes were enriched in the developing cortex (e.g., IGF2, PEG3). These findings reveal aspects of human adrenal development and have clinical implications for understanding primary adrenal insufficiency and related postnatal adrenal disorders, such as adrenal tumor development, steroid disorders, and neonatal stress.

Microfocus computed tomography for fetal postmortem imaging: an overview

Over the last few years, fetal postmortem microfocus computed tomography (micro-CT) imaging has increased in popularity for both diagnostic and research purposes. Micro-CT imaging could be a substitute for autopsy, particularly in very early gestation fetuses for whom autopsy can be technically challenging and is often unaccepted by parents. This article provides an overview of the latest research in fetal postmortem micro-CT imaging with a focus on diagnostic accuracy, endovascular staining approaches, placental studies and the reversibility of staining. It also discusses new methods that could prove helpful for micro-CT of larger fetuses. While more research is needed, contrast-enhanced micro-CT has the potential to become a suitable alternative to fetal autopsy. Further research using this novel imaging tool could yield wider applications, such as its practise in imaging rare museum specimens.

Forensic applications of micro-computed tomography: a systematic review

Purpose

The aim of this systematic review was to provide a comprehensive overview of micro-CT current applications in forensic pathology, anthropology, odontology, and neonatology.

Methods

A bibliographic research on the electronic databases Pubmed and Scopus was conducted in the time frame 01/01/2001–31/12/2021 without any language restrictions and applying the following free-text search strategy: “(micro-computed tomography OR micro-CT) AND (forensic OR legal)”. The following inclusion criteria were used: (A) English language; (B) Application of micro-CT to biological and/or non-biological materials to address at least one forensic issue (e.g., age estimation, identification of post-mortem interval). The papers selected by three independent investigators have been then classified according to the investigated materials.

Results

The bibliographic search provided 651 records, duplicates excluded. After screening for title and/or abstracts, according to criteria A and B, 157 full-text papers were evaluated for eligibility. Ninety-three papers, mostly (64) published between 2017 and 2021, were included; considering that two papers investigated several materials, an overall amount of 99 classifiable items was counted when referring to the materials investigated. It emerged that bones and cartilages (54.55%), followed by teeth (13.13%), were the most frequently analyzed materials. Moreover, micro-CT allowed the collection of structural, qualitative and/or quantitative information also for soft tissues, fetuses, insects, and foreign materials.

Conclusion

Forensic applications of micro-CT progressively increased in the last 5 years with very promising results. According to this evidence, we might expect in the near future a shift of its use from research purposes to clinical forensic cases.

Comparison of postmortem whole-body contrast-enhanced microfocus computed tomography and high-field magnetic resonance imaging of human fetuses

OBJECTIVE

Although fetal autopsy is generally recommended to confirm or refute the antemortem diagnosis, parental acceptance of the procedure has fallen over time, mainly due to its invasiveness. Contrast-enhanced microfocus CT (micro-CT) and high-field magnetic resonance imaging (HF-MRI, ≥ 3 Tesla) have both been suggested as non-invasive alternatives to conventional fetal autopsy for fetuses < 20 weeks of gestation. The aim of this study was to compare these two modalities in postmortem whole-body fetal imaging.

METHODS

In this study, the imaging process and quality of micro-CT and HF-MRI were compared using both qualitative and quantitative assessments. For the qualitative evaluation, fetal anatomy experts scored 56 HF-MRI and 56 micro-CT images of four human fetuses aged 13-18 gestational weeks on two components: overall image quality and the ability to recognize and assess 21 anatomical structures. For the quantitative evaluation, participants segmented manually three organs with increasing complexity to assess interobserver variability. In addition, the signal-to-noise and contrast-to-noise ratios of five major organs were determined.

RESULTS

Both imaging techniques were able to reach submillimeter voxel size. The highest resolution of micro-CT was 22 µm (isotropic), while the highest resolution of HF-MRI was 137 µm (isotropic). The qualitative image assessment form was sent to 45 fetal anatomy experts, of whom 36 (80%) responded. It was observed that micro-CT scored higher on all components of the qualitative assessment compared with HF-MRI. In addition, the quantitative assessment showed that micro-CT had lower interobserver variability and higher signal-to-noise and contrast-to-noise ratios.

CONCLUSIONS

Our findings show that micro-CT outperforms HF-MRI in postmortem whole-body fetal imaging in terms of both quantitative and qualitative outcomes. Combined, these findings suggest that the ability to extract diagnostic information is greater when assessing micro-CT compared with HF-MRI images. We, therefore, believe that micro-CT is the preferred imaging modality as an alternative to conventional fetal autopsy for early gestation and is an indispensable tool in postmortem imaging services. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Post-mortem perinatal imaging: what is the evidence?

Post-mortem imaging for the investigation of perinatal deaths is an acceptable tool amongst parents and religious groups, enabling a less invasive autopsy examination. Nevertheless, availability is scarce nationwide, and there is some debate amongst radiologists regarding the best practice and optimal protocols for performing such studies. Much of the published literature to date focusses on single centre experiences or interesting case reports. Diagnostic accuracy studies are available for a variety of individual imaging modalities (e.g. post-mortem CT, MRI, ultrasound and micro-CT), however, assimilating this information is important when attempting to start a local service.In this article, we present a comprehensive review summarising the latest research, recently published international guidelines, and describe which imaging modalities are best suited for specific indications. When the antenatal clinical findings are not supported by the post-mortem imaging, we also suggest how and when an invasive autopsy may be considered. In general, a collaborative working relationship within a multidisciplinary team (consisting of radiologists, radiographers, the local pathology department, mortuary staff, foetal medicine specialists, obstetricians and bereavement midwives) is vital for a successful service.

Micro-CT yields high image quality in human fetal post-mortem imaging despite maceration

BACKGROUND

Current clinical post-mortem imaging techniques do not provide sufficiently high-resolution imaging for smaller fetuses after pregnancy loss. Post-mortem micro-CT is a non-invasive technique that can deliver high diagnostic accuracy for these smaller fetuses. The purpose of the study is to identify the main predictors of image quality for human fetal post-mortem micro-CT imaging.

METHODS

Human fetuses were imaged using micro-CT following potassium tri-iodide tissue preparation, and axial head and chest views were assessed for image quality on a Likert scale by two blinded radiologists. Simple and multivariable linear regression models were performed with demographic details, iodination, tissue maceration score and imaging parameters as predictor variables.

RESULTS

258 fetuses were assessed, with median weight 41.7 g (2.6-350 g) and mean gestational age 16 weeks (11-24 weeks). A high image quality score (> 6.5) was achieved in 95% of micro-CT studies, higher for the head (median = 9) than chest (median = 8.5) imaging. The strongest negative predictors of image quality were increasing maceration and body weight (p < 0.001), with number of projections being the best positive imaging predictor.

CONCLUSIONS

High micro-CT image quality score is achievable following early pregnancy loss despite fetal maceration, particularly in smaller fetuses where conventional autopsy may be particularly challenging. These findings will help establish clinical micro-CT imaging services, addressing the need for less invasive fetal autopsy methods.

A pragmatic evidence-based approach to post-mortem perinatal imaging

Post-mortem imaging has a high acceptance rate amongst parents and healthcare professionals as a non-invasive method for investigating perinatal deaths. Previously viewed as a 'niche' subspecialty, it is becoming increasingly requested, with general radiologists now more frequently asked to oversee and advise on appropriate imaging protocols. Much of the current literature to date has focussed on diagnostic accuracy and clinical experiences of individual centres and their imaging techniques (e.g. post-mortem CT, MRI, ultrasound and micro-CT), and pragmatic, evidence-based guidance for how to approach such referrals in real-world practice is lacking. In this review, we summarise the latest research and provide an approach and flowchart to aid decision-making for perinatal post-mortem imaging. We highlight key aspects of the maternal and antenatal history that radiologists should consider when protocolling studies (e.g. antenatal imaging findings and history), and emphasise important factors that could impact the diagnostic quality of post-mortem imaging examinations (e.g. post-mortem weight and time interval). Considerations regarding when ancillary post-mortem image-guided biopsy tests are beneficial are also addressed, and we provide key references for imaging protocols for a variety of cross-sectional imaging modalities.

Clinical academic radiographers - A challenging but rewarding career

OBJECTIVES

To explain what a clinical academic career can be, what it can lead to for the individual, profession and most importantly the patient, and why these roles are so important to radiography.

KEY FINDINGS

Multiple challenges to the adoption of clinical academic careers exist, including achievable measurable outcomes, visibility & senior support, and balancing different time demands. Equally the rewards are wide ranging and can advance both the individual and profession through role extension opportunities, increased career progression, patient benefits, and academic and research skills.

CONCLUSION

Clinical academic careers can provide advantages for the individual, department, profession and most importantly the patient with advanced clinical practice through evidenced based research.

IMPLICATIONS FOR PRACTICE

Improving clinical academic careers within Radiography will promote research participation and increase radiographic roles in patient-centred research delivery and development. Combining evidenced based research with academic skills will lead to improved patient care and better clinical outcomes.