Purpose or Case Report: 1. Review the safety, limitations and advantages of fetal cardiac MR (CMR)
2. Discuss potentialindications of fetal CMR
3. Describe the technique of fetal CMR, including imaging sequences, imaging planes, the method
of overcoming motion artifact
4. Illustrate the appearance of normal fetal cardiac structures and present a modified anatomic
segmental approach of congenital heart disease (CHD) at prenatal CMR
5. Demonstrate examples of fetal CMR in the evaluation of various cardiovascular anomalies
Methods & Materials: 924 pregnant women were referred to a children’s hospital for a fetal CMR from January 2006 to June 2017, 638 due to the finding of a cardiovascular anomaly by echocardiogram (echo) and 286 due to technically limited echo, but thought to likely be normal. Studies were performed after 20 weeks gestation. Fetal CMR was performed at 1.5 T or 3.0 T (Discovery 750; GE Medical
Systems). Sequences included steady-state free-precession (SSFP), non gated SSFP cine, single-shot turbo spin echo (SSTSE) and non-gatedphase contrast (PC) cinesequences. Optimal imaging included transverse view of the fetal thorax, the four-chamber, short-axis, coronal and oblique sagittal planes of the fetal heart. Follow up postnatal diagnoses were confirmed by postnatal imaging, surgery and/or autopsy.
Results: Examples of Fetal cardiac MRI cases will be presented. In 638 cases with anomalies, Obstetric US were correct in 46.9% (299/638), fetal echos were correct in 83.2% (531/638), CMR were correct in 82.1% (524/638) when compared to postnatal findings. Fetal echoes had a higher specificity for evaluating ventricular size, septal defects and valve anomalies. CMR was more useful in evaluating extracardiac aortic arch, superior vena cava and malposition anomalies,heart diverticulum, pericardium cyst. CMR was technically limited in 9 cases due to polyhydramnios.
In 286 cases, CMR performed due to technically inadequateechocardiography (maternal obesity, maternal abdominal wall edema, oligohydramnios, fetal position, twins, et al), had follow up. All of these cases were interpreted as normalby CMR and confirmed at FU.
Key point of scan technique includeSSFP sequence with overlapping slice, improving the artifacts is SSFP with radial k-space sampling.
Conclusions: While Fetal echo is the first choice in the evaluation of fetal cardiovascular anomalies; fetal CMR may be a useful adjunct particularly when echocardiography is limited.