Fetal magnetic resonance imaging (MRI) is a third-level diagnostic tool for the study of fetal
malformations and has been applied in the diagnosis and definition of fetal central nervous system (CNS) and
other fetal, placental and uterine diseases. Recent developments of new realtime sequences during free breathing
without cardiac triggering have established a potential role of MRI in the study of fetal heart: MRI can study the
morphology using steady-state free precession (TrueFISP) sequences on sagittal, coronal and axial planes,
orthogonally oriented to the fetal diaphragm and allows to identify the viscero-atrial situs, the heart and its axis. It
is also possible to perform a dynamic study, through the acquisition of cine-MR sequences with real-time steadystate
free precession (SSFP) oriented according to the standard projections used in fetal echocardiographic
scannings. At the moment, there is no evidence that short-term exposure to electromagnetic fields of 1.5 T or less
harms the fetus. MRI can analyze the normal anatomy by transverse, long axis and angulated views to visualize
the principal cardiac planes. There are recent evidences of a useful role of MRI in the definition of congenital
heart disease (CHD). The study of fetal CHD can be made by direct signs such as volumetric abnormalities of the
heart and of the cardiac chambers, abnormalities of the structure, thickness and signal intensity of the myocardial
walls, anomalies of the cardiac axis orientation, defects of the ventricular and atrial septa and anomalies of the
origin, size and course of the great arteries. The difficulty to recognize a “normal” anatomical structure in the
reference projections, the increase of the vascular size before a vascular stenosis and the presence of
cardiomegaly and pericardial effusion are instead considered as indirect signs of CHD are considered as suspect
for fetal CHD.Despite current limitations, fetal MRI seems to be a promising diagnostic method for the
assessment of the fetal heart.
Keywords: Fetal MRI, Fetal Heart, Congenital Heart Disease.
