Postmortem fetal imaging: prospective blinded comparison of two‐dimensional ultrasound with magnetic resonance imaging

Abstract

Objective To compare the diagnostic rate and accuracy of 3‐Tesla (T) postmortem magnetic resonance imaging (PM‐MRI) and postmortem ultrasound (PM‐US) in an unselected fetal population. Methods We performed prospectively, in a blinded manner, 3‐T PM‐MRI and PM‐US on 160 unselected fetuses at 13–41 weeks of gestation. All imaging was reported according to a prespecified template, for five anatomical regions: brain, thorax, heart, abdomen and spine. The rates of non‐diagnostic results for PM‐US and PM‐MRI were compared and, for results that were diagnostic, we calculated sensitivity, specificity and concordance rates for each anatomical region, using conventional autopsy as the reference standard. Results 3‐T PM‐MRI performed significantly better than did PM‐US overall and in particular for fetuses ≥ 20 weeks' gestation. Specifically, the non‐diagnostic rates for PM‐MRI vs PM‐US were 4.4% vs 26.9% (7/160 vs 43/160; P < 0.001) for the brain, 5.2% vs 17.4% (8/155 vs 27/155; P < 0.001) for the thorax, 3.8% vs 30.6% (6/157 vs 48/157; P < 0.001) for the heart and 3.2% vs 23.6% (5/157 vs 37/157; P < 0.001) for the abdomen. For the spine, both techniques showed an equally low non‐diagnostic rate. When both postmortem imaging techniques were diagnostic, they had similar accuracy, with no difference in sensitivity or specificity, and similar concordance with autopsy (PM‐US, 79.5–96.5%; PM‐MRI, 81.6–99.1%). Conclusions PM‐MRI performed significantly better than PM‐US in this unselected population, due mainly to a lower non‐diagnostic rate. PM‐MRI should remain the first‐line imaging investigation for perinatal autopsy, but PM‐US could be considered if MRI is not available, albeit with a higher non‐diagnostic rate. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Latest developments in post‐mortem foetal imaging

“…New data has also shown that where images are of diagnostic quality, the ability to diagnose congenital anomalies is comparable with 3T PMMR (PMUS 81.8‐96.5% vs PMMR 81.6‐99.1%). However, there was a greater likelihood of non‐diagnostic PMUS studies compared with PMMR.…”

“…However, there was a greater likelihood of non‐diagnostic PMUS studies compared with PMMR. This is particularly notable for brain and cardiac imaging where PMUS was non‐diagnostic in a third of cases compared with PMMR which was only non‐diagnostic in less than 5% ( P < .001) . The reasons for this may be partly due to overlapping cranial sutures from maceration or extraction methods, precluding a clear sonographic window, and the difficulty in delineating cardiac anomalies generated by the lack of Doppler flow in the post‐mortem population.…”

Fetal thymus in the middle and late trimesters: Morphometry and development using post‑mortem 3.0T MRI

“…Currently, fetal magnetic resonance imaging (MRI) has been widely accepted as a complementary modality to US in prenatal diagnosis (10,11) However, it is still a challenge to identify abnormalities, especially in the middle trimester when the fetus is comparatively small and pulse artifacts may present. Furthermore, in the later stages of fetal development, the thymus cannot be easily observed due to changes of fetal position and overlapping of limbs (10).…”

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

“…Recent literature has suggested that post‐mortem ultrasound (PMUS) in the perinatal population could offer a potential alternative imaging solution . One recent study even suggested that fetal and neonatal PMUS could provide the same diagnostic accuracy for cause of death as 3T PMMR, when the images were of diagnostic quality . With ultrasound imaging being more affordable and less time‐consuming (approximately 20 min for PMUS versus 45‐90 min for PMMR), one potential imaging protocol may be to use PMUS as a triage tool for non‐invasive autopsies (NIAs), whilst referring only complex cases or nondiagnostic PMUS studies for PMMR, thus saving time and clinical resources.…”