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Postmortem fetal organ volumetry using magnetic resonance imaging and comparison to organ weights at conventional
A C G Breeze1, F A Gallagher, D J Lomas
1Division of Maternal-Fetal Medicine, Cambridge University Hospitals NHS Foundation Trust, Addenbrooke's Hospital, Hills Road, Cambridge, UK.
Objectives:
Following perinatal death, organ weights at autopsy may provide evidence of growth restriction and pulmonary hypoplasia. Whilst postmortem magnetic resonance imaging (MRI) may provide comparable information to autopsy about structural abnormalities, its ability to provide reproducible data about organ size has yet to be determined. We examined the feasibility of using postmortem MRI to provide estimates of organ size and weight.
Methods:
Twenty-five fetuses of gestational age from 16 to 40 weeks underwent postmortem MRI prior to autopsy. Fetal lung, brain and liver volume estimations were performed by two observers using the stereology technique on postmortem MRI slices. Fetal lung, brain and liver weights were recorded at autopsy. Organ volume estimates and autopsy organ weights were compared using regression analysis, and estimates of fetal organ densities made. Interobserver variability was assessed using a Bland-Altman plot. Receiver-operating characteristics curve (ROC) analysis compared MRI brain : liver volume ratios to autopsy brain : liver weight ratios.
Results:
A linear relationship between organ volume estimates and organ weight was observed. Estimated densities for the fetal brain, liver and lung were 1.08 g/cm(3), 1.15 g/cm(3) and 1.15 g/cm(3), respectively. Interobserver 5th and 95th percentile limits of agreement for fetal brain, liver and lung were - 5.4% to + 7.9%, - 11.8% to + 8.3% and - 14.3% to + 8.7%, respectively. For MRI organ volumes to detect a brain weight : liver weight ratio > or = 4, ROC analysis demonstrated an area under the curve of 0.61, with an optimal cut-off of 4.1.
Conclusion:
Postmortem MRI organ volumetry can be used to estimate weights of major fetal organs. This may increase the information obtained from a minimally-invasive perinatal autopsy, particularly in the context of pulmonary hypoplasia and intrauterine growth restriction, where differential organ growth plays a major part in assessment of the underlying pathology.
Insights
Postmortem MRI can estimate fetal organ weights, aiding in diagnosing growth restriction and pulmonary hypoplasia. This technique offers valuable data from minimally-invasive perinatal autopsies.
Area of Science:
- Medical Imaging
- Fetal Pathology
- Forensic Medicine
Background:
- Autopsy organ weights are crucial for diagnosing fetal growth restriction and pulmonary hypoplasia.
- Postmortem MRI shows potential for structural assessment but its utility for organ size estimation is unproven.
Purpose of the Study:
- To assess the feasibility of using postmortem MRI for estimating fetal organ size and weight.
- To determine if postmortem MRI volumetry can provide reproducible organ weight estimates.
Main Methods:
- Postmortem MRI was performed on 25 fetuses (16-40 weeks gestation) before autopsy.
- Fetal lung, brain, and liver volumes were estimated using stereology on MRI slices.
- Organ volumes were correlated with autopsy weights; interobserver variability and diagnostic accuracy were assessed.
Main Results:
- A linear relationship was found between MRI-estimated organ volumes and autopsy organ weights.
- Estimated fetal organ densities were: brain 1.08 g/cm³, liver 1.15 g/cm³, lung 1.15 g/cm³.
- Interobserver agreement for volume estimates was within acceptable limits; ROC analysis showed potential for detecting abnormal brain:liver ratios.
Conclusions:
- Postmortem MRI organ volumetry is a feasible method for estimating fetal organ weights.
- This technique can enhance minimally-invasive perinatal autopsies, especially for conditions involving differential organ growth like intrauterine growth restriction and pulmonary hypoplasia.
