Post-mortem examination of human fetuses: a comparison of whole-body high-field MRI at 9.4 T with conventional MRI and invasive autopsy.

Background: Conventional whole-body MRI at 1.5 T does not provide adequate image quality of small fetuses, thus reducing its potential for use as an alternative to invasive autopsy. High-field whole-body MRI at 9.4 T provides good images of small animals. We therefore compared the diagnostic usefulness of high-field MRI with conventional MRI for post-mortem examination of human fetuses.

Methods: We did whole-body MRI at 9.4 T and 1.5 T on 18 fetuses of less than 22 weeks' gestation, using three-dimensional T(2)-weighted fast-spin echo sequences, before doing invasive autopsy. Images obtained with MRI for each system were compared with the findings of invasive autopsy in a blinded manner. Tissue contrast of 14 different regions was compared on 1.5 T and 9.4 T images that were provided by paediatric radiologists separately and in a random order, and image quality was scored on a four-point scale. The primary endpoint was diagnostic accuracy.

Findings: Spatial resolution, tissue contrast, and image quality of all organ systems were much better with high-field MRI than with conventional MRI. All structural abnormalities that were detected with invasive autopsy and internal examination of visceral organs were also detected with high-field MRI, whereas conventional MRI was not diagnostically useful in 14 (78%) cases.

Interpretation: Whole-body high-field MRI is a feasible option for post-mortem examination of human fetuses, and can provide good tissue characterisation even in small fetuses (5 g). The use of MRI at 9.4 T might be helpful in the development of a minimally invasive perinatal autopsy system.

Funding: Department of Health Policy Research Programme, British Heart Foundation, National Institute of Health Research, Higher Education Funding Council for England, Biotechnology and Biological Sciences Research Council, Engineering and Physical Sciences Research Council, Great Ormond Street Hospital, University College London (UCL) Institute of Child Health, UCL Hospital, and UCL.