Postmortem Examination of Human Fetuses: A Comparison of Whole-Body High-Field MRI at 9.4 Tesla With Conventional MRI and Invasive Autopsy

Abstract

More than 10 years ago, conventional whole-body MRI at 1.5 Tesla (T) was proposed as a more rapid, less invasive alternative to conventional invasive perinatal autopsy. However, there is poor agreement between the perinatal autopsy findings and the postmortem MRI at 1.5 T. Studies in small animals have shown that good images of anatomy can be obtained using high-field MRI at 9.4 T and have led to the present investigation. This prospective blinded study compared the diagnostic accuracy of high-field MRI at 9.4 T and conventional MRI for postmortem examination of small human fetuses. A total of 18 fetuses of less than 22 weeks' gestation were examined using 3-dimensional T2-weighted fast-spin echo sequences for whole-body MRI with 1.5 T and 9.4 T scanners before invasive autopsy. The MRI images for each system were compared to the invasive autopsy findings by investigators who were blinded to the MRI settings. Tissue contrast in 14 different regions for MRI images at 1.5 T and 9.4 T was compared separately and in a random order. The quality of the MRI images was rated on a 4-point scale. For all organ systems, high-field MRI at 9.4 T provided superior image quality scores than conventional MRI at 1.5 T and provided greater spatial resolution, higher tissue contrast, and better diagnostic information. High-field MRI also was able to detect all the structural abnormalities in fetal organs found with invasive autopsy. In contrast, conventional MRI had no diagnostic value in 14 (78%) of the cases. These findings indicate that use of MRI at 9.4 T may be a satisfactory noninvasive alternative to conventional autopsy in both large and small human fetuses.