Feasibility of MRI of the fetal heart with balanced steady-state free precession sequence along fetal body and cardiac planes.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of imaging the fetal heart with a balanced steady-state free precession MRI sequence along the body and cardiac axes after inadequate echocardiography. SUBJECTS AND METHODS: After technically inadequate echocardiography, MRI was performed on 20 fetuses (mean gestational age, 24 weeks; range, 18-32 weeks) at risk of congenital heart disease. MRI was attempted along the three fetal body planes (n = 20) and cardiac axes (n = 3) without fetal sedation. The images were analyzed with an anatomic segmental approach. Each feature was classified as well visualized or poorly or not visualized. In each group, the Student's t test was used to assess the relation between visibility of fetal cardiac features and gestational age.
RESULTS: Imaging was possible along the fetal body and cardiac axes. In the axial plane, a balanced four-chamber view was obtained in all fetuses, enabling evaluation of heart position, axis, chambers, and interventricular septum. The left and right ventricular outflow tracts were well visualized in 12 (60%) and nine (45%) of the fetuses, respectively; the three-vessel view was obtained in 10 fetuses (50%). With the combination of sagittal and coronal views, both ventricular outflow tracts were assessed in all fetuses. The superior and inferior venae cavae were identified in all fetuses, and at least one pulmonary vein was visualized in 17 fetuses (85%). There were no statistically significant differences between gestational age and lack of visualization of a cardiac feature that was attributed to fetal motion.
CONCLUSION: MRI of the fetal heart with a steady-state free precession sequence in multiple planes and image analysis with an anatomic segmental approach to congenital heart disease are possible in situations that limit echocardiography.