Postmortem microfocus computed tomography for noninvasive autopsies: experience in >250 human fetuses

Abstract

BACKGROUND: Noninvasive imaging autopsy alternatives for fetuses weighing <500 grams are limited. Microfocus computed tomography has been reported as a viable option in small case series with the potential to avoid an invasive autopsy. Implementation of postmortem microfocus computed tomography in a large cohort as part of routine clinical service has yet been unreported, and realistic "autopsy prevention rates" are unknown. OBJECTIVE: This study aimed to describe the range of abnormalities detectable on fetal microfocus computed tomography in a clinical setting and additional findings identified on the antenatal ultrasound and to estimate the invasive autopsy avoidance rate (ie, cases in which imaging was sufficient to deem autopsy unnecessary). STUDY DESIGN: A prospective observational case series of all fetuses referred for microfocus computed tomography imaging at a single institution was conducted for 3 years (2016e2019). Imaging was reported by 2 pediatric radiologists before autopsy, with "decision to proceed" based on the specialist perinatal pathologists' judgment and parental consent. Agreement rates between microfocus computed tomography and antenatal ultrasound were evaluated, and where feasible, diagnostic accuracy for microfocus computed tomography was calculated using autopsy as a reference standard. RESULTS: A total of 268 fetuses were included (2e350 grams body weight; 11e24 weeks' gestation), with cause for demise in 122 of 268 (45.5%). Of the 122 fetuses, 64 (52.5%) exhibited fetal anomalies. Although 221 of 268 (82.5%) fetuses had consent for invasive autopsy, only 29 of the 221 (13.1%) underwent this procedure, which implied an autopsy avoidance rate of 192 of 221 (86.9%). Complete agreement was present for all brain, thoracic, and abdominal pathologies, whereas sensitivity and specificity for cardiac anomalies were 66.7% and 91.7%, respectively. Microfocus computed tomography and antenatal ultrasound agreement was found in 219 of 266 cases (81.9%), with partial agreement in 21 of 266 (7.9%) and disagreement in 26 of 266 (10.5%), mostly because of additional cardiac, soft tissue, or genitourinary findings by microfocus computed tomography, which were not seen on the ultrasound. CONCLUSION: Fetal microfocus computed tomography imaging is a viable and useful tool for imaging early gestational fetuses and can avoid the need for invasive autopsy. Confirmation of antenatal diagnoses is achieved in most cases, and additional anomalies may also be detected.

Micro-CT Imaging of Pediatric Thyroglossal Duct Cysts: A Prospective Case Series

“…Previous work has already discussed the benefits of this technique for other uses, such as for imaging excised whole organs [e.g., cardiac ( 19 ), brain ( 20 )] as well as assessing cartilage rings in a pediatric case of tracheal stenosis ( 13 ). Micro-CT is becoming a more widely accepted tool for non-invasive post-mortem whole body fetal imaging ( 10 , 12 ), as it allows internal visualization without surgical dissection. These studies have also demonstrated that iodine based micro-CT does not affect the histologic or immunohistochemical phenotype of normal tissues [skin biopsies and blood vessels ( 21 ) or diseased tissues, including cardiomyopathic cardiac tissue ( 22 ), cystic kidneys ( 23 ), and in neoplastic lesions of the heart ( 24 ), and brain ( 20 )].…”

“…It uses multiple X-rays to create a highresolution 3D volume imaging dataset at a spatial resolution comparable to light microscopy (voxel size down to 1 micron) (9). At our institution, we currently provide a post-mortem fetal micro-CT clinical imaging service (10)(11)(12), however only a few publications have reported using this technology for excised human surgical specimens (13)(14)(15)(16) and the utility of this imaging modality for pediatric thyroglossal duct cyst specimens is unknown, but clearly has appeal in providing high resolution 3D imaging of complex neck structures to aid pathological dissection.…”

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

“…Two of the largest case series published comparing foetal micro-CT with standard autopsy [ 15 , 29 ], both demonstrated high sensitivity and specificity rates for overall diagnosis (94–100% sensitivity, 90–100% specificity) [ 15 , 29 ]. The main drawback, however, was the requirement for tissue staining with an iodinated contrast medium which caused some residual discolouration of the foetus and tissue shrinkage [ 30 ] and can take several days for full iodination to occur, depending on the size of the foetus.…”

Postmortem Micro-CT of Human Fetal Heart—A Systematic Literature Review

“…Currently, there are different non-invasive alternatives to an autopsy that allow the study of the human fetal heart. Contrast-enhanced micro-computed tomography (micro-CT) is one of the alternative methods that has proven to be feasible in the postmortem evaluation of the human fetal heart since the 8° WG, reaching adequate detection rate compared to the gold standard technique [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Besides the clinical domain, it can be used for educational and teaching purposes, having the potential to generate overriding medical and non-medical areas for future scientific and engineering advancements in the field of pediatric cardiology [ 35 , 36 , 37 , 38 , 39 , 40 ].…”

“…When compared to other non-invasive postmortem techniques, micro-CT seems to have a better balance between advantages and limitations for studying isolated fetal hearts [ 41 , 42 , 43 , 44 ]. Previously published studies on this technique are heterogeneous in their objectives, studied population, methods and imaging analysis [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ].…”