To compare the diagnostic usefulness of high-field with low-field magnetic resonance imaging (MRI) and stereomicroscopic autopsy for examination of the heart in fetuses at or under 20 weeks' gestation.
Prior to invasive stereomicroscopic autopsy, MRI scans at 9.4, 3.0 and 1.5 T were performed on 24 fetuses between 11 and 20 weeks' gestation, including 10 fetuses with cardiac abnormalities. The ability to visualize different heart structures was evaluated according to the different field strength MRI magnets used and gestational age at examination.
On 1.5- and 3.0-T MRI, only the heart situs and four-chamber view could be visualized consistently (in 75% or more of cases) when the fetus was beyond 16 weeks' gestation, but other heart structures could not be visualized for fetuses at any gestational age. In contrast, using high-field MRI at 9.4 T, the heart situs, four-chamber view and the outflow tracts could be visualized in all fetuses irrespective of gestational age. Using high-field MRI, the sensitivity for detecting an abnormality of the four-chamber view was 66.7% (95% CI, 30.1–92.1%) with a specificity of 80.0% (95% CI, 51.9–95.4%). For abnormalities of the outflow tracts, sensitivity was 75.0% (95% CI, 20.3–95.9%) and specificity 100.0% (95% CI, 83.3–100.0%). Eight fetuses out of 10 with congenital heart disease (CHD) were classified as having major CHD. High-field MRI at 9.4 T was able to identify seven out of the eight cases of major CHD.
High-field MRI at 9.4 T seems to be an acceptable alternative approach to invasive stereomicroscopic autopsy for fetuses with CHD at or below 20 weeks' gestation. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.