Magnetic resonance imaging in the normal fetal heart and in congenital heart disease.

OBJECTIVE: To evaluate prospectively the feasibility of magnetic resonance
imaging (MRI) for assessment of the fetal heart for congenital heart disease
(CHD).
METHODS: This was a cross-sectional study, including 66 fetuses with a normal
heart and 40 with CHD. The fetal heart was examined on MRI using axial
steady-state free precession (SSFP) sequences. Regression analysis was used to
investigate the effect on the ability to visualize cardiac anatomy of gestational
age at examination, maternal body mass index, presence of fetal cardiac
abnormality, fetal movements, fetal lie and twinning. The sensitivity and
specificity of detecting cardiac defects were calculated.
RESULTS: The four-chamber view was visualized in 98.1% of fetuses. The
sensitivity of detecting a cardiac defect on the four-chamber view was 88% and
the specificity 96%. The ability to visualize the left and right outflow tracts
was only influenced by the presence of fetal movements: for the left outflow
tract 94.4 vs. 50.0% visualization and for the right outflow tract 92.6 vs. 53.8%
visualization without and with fetal movements, respectively. The sensitivity of
detecting a cardiac defect of the left outflow tract was 63% and the specificity
100%, while sensitivity and specificity were 59 and 97%, respectively, for the
right outflow tract.
CONCLUSIONS: Despite the use of SSFP sequences, MRI in the fetal heart remains of
limited value. It can only be used as a second-line approach for abnormalities of
the four-chamber view suspected at prenatal ultrasound.