Abstract:

Objective To explore the diagnostic value of magnetic resonance imaging (MRI) on fetal cardiac malposition. Methods MRI examinations were performed 24 to 48 h after routine ultrasound examinations on 57 pregnant women with gestation of 20 to 36 weeks. The imaging protocols included 2 dimension fast imaging employing steady-state acquisition (2D FIESTA), single-shot fast spin echo (SSFSE), T1-weighted fast inversion recovery motion insensitive (FIRM) and dynamic FIESTA sequences in the axial, frontal and sagittal planes relative to the fetal brain, thorax, abdomen, especially lung and heart. Prenatal ultrasound and MRI findings were compared with postnatal diagnoses (n=49) or autopsy (n=8). Postnatal evaluation included a variety of imaging and surgery. Results There were 5 cases of primary fetal cardiac malposition (dextrocardia) and 52 cases of secondary fetal cardiac malposition. The causes of secondary cardiac malposition included right pulmonary hypoplasia (n=7), congenital diaphragmatic hernia (CDH, n=18), congenital cystic adenomatoid malformation (CCAM, n=24), bronchopulmonary sequestration (BPS, n=2) and mediastinal mass (n=1). Conclusion Prenatal MRI is effective in the assessment of fetal cardiac malposition and its causes with the integrated application of sequences. The same section of FIESTA sequence can reveal the abnormal position of fetal heart and other chest lesions causing changes in fetal heart position. Dynamic FIESTA sequence can demonstrate obvious abnormal cardiac blood flow. Both SSFSE and FIRM sequences can well display other chest abnormalities causing changes in fetal heart position.

Key words: fetus, heart, malposition, magnetic resonance imaging