Evaluation of post-mortem high-field MRI at 7T compared to conventional autopsy: a morphometric study

Objective. The aim of our study was to establish if high-field post-mortem MRI at 7T can perform three-dimensional measurements of the fetal heart, and retrieve results comparable to post-mortem macroscopic measurements performed at autopsy, in fetuses with whole body weight below 500 g. Methodology. Twelve second-trimester fetuses with gestational ages ranging from 13 to 19 weeks of gestation were considered. All fetuses resulted from therapeutic termination of pregnancy (TOP) due to plurimalformative syndromes or chromosomal anomalies. All cases were immersed in 10% formalin solution, and after proper fixation they were examined using high-field MRI at 7T. After post-mortem imagistic examination, all cases were submitted to conventional autopsy. Three-axis cardiac measurements were performed by both examination methods, using the same landmarks. Results. We observed a strong correlation between post-mortem MRI measurements at 7T and post-mortem macroscopic measurements at autopsy, with p<0.001. The coefficient of correlation (r) for all three axes was above or equal to 0.90. Bland Altman plots showed overall good agreement between measurements performed by both methods. Conclusions. Using 7T post-mortem MRI for three-dimensional morphometric evaluation of the fetal heart in the second-trimester fetuses with a body weight less than 500 g, the obtained results are comparable to the macroscopic measurements performed during conventional autopsy.