Postmortem 9.4-T MRI for Fetuses With Congenital Heart Defects Diagnosed in the First Trimester

Abstract

Objective: To evaluate the feasibility of 9. 4-T postmortem MRI (pm-MRI) for assessment of major congenital heart defects (CHD) cases terminated in the early stage of gestation.

Methods: Fetuses with CHD detected by the detailed first-trimester ultrasound scan and terminated before 18 gestational weeks were recruited between January 2018 and June 2020. All fetuses were offered 9.4-T pm-MRI examinations and those terminated over 13⁺⁶ weeks were offered conventional autopsies simultaneously. Findings of pm-MRI were compared with those of conventional autopsy and prenatal ultrasound.

Results: A total of 19 fetuses with major CHD were analyzed, including 6 cases of the atrioventricular septal defect, 5 cases of Tetralogy of Fallot, 3 cases of hypoplastic left heart syndrome, 1 case of tricuspid atresia, 1 case of transposition of the great arteries, 1 case of severe tricuspid regurgitation, and 2 cases of complex CHD. Pm-MRI had concordant findings in 73.7% (14/19) cases, discordant findings in 15.8% (3/19) cases, and additional findings in 10.5% (2/19) cases when compared with prenatal ultrasound. Pm-MRI findings were concordant with autopsy in all 8 CHD cases terminated over 13⁺⁶ weeks.

Conclusion: It is feasible to exhibit the structure of fetal heart terminated in the first trimester clearly on 9.4-T pm-MRI with an optimized scanning protocol. High-field pm-MRI could provide medical imaging information of CHD for those terminated in the early stage of gestation, especially for those limited by conventional autopsy.

Keywords: 94-T magnetic resonance images; congenital heart defects; first- trimester ultrasound scan; postmortem magnetic resonance imaging; prenatal ultrasound.

Figure 1

Fetal hearts and lungs in different gestational weeks (17, 15, 13, and 12 weeks, respectively).

Figure 2

T1-weighted magnetic resonance consecutive images at 9.4 T of a fetus with normal cardiac anatomy, following termination of pregnancy at 13+1 weeks of gestation. (a) at the level of four-chamber view, showing a normal situs of the heart surrounded by the lungs, and a normal four-chamber view. (b,c) at the level of the left outflow tract showing the medial aortic wall was continuous with the ventricular septum and aortic valve. (d) at the level of the right outflow tract with a pulmonary artery that originates from the right ventricle with the clear bifurcation of the main pulmonary artery and left pulmonary artery. (e) at the level of the three-vessel view, the main pulmonary artery, ascending aorta, and superior vena cava are arranged in a straight line that extends from the left anterior to the right posterior. (f) at the level of the three-vessel and trachea view showing the transverse aortic arch and isthmus merge into the descending aorta, as does the pulmonary trunk and ductus arteriosus, creating a V-shaped configuration. (g–i) showing the right subclavian artery that branches off the aorta. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; RL, right lung; LL, left lung; TV, tricuspid valve; MV, mitral valve; LLPA, left lung pulmonary vein; DA, descending thoracic aorta; IVS, interventricular septum; LVOT, left ventricle outflow tract; AV, aortic valve; L-Bro, left bronchus; R-Bro, right bronchus; LPA, left pulmonary vein; RVOT, right ventricle outflow tract; Tra, trachea; PA, pulmonary artery; AO, aorta; AA, aortic arch; SVC, superior vena cava; RSA, right subclavian artery.

Figure 3

Prenatal ultrasound, postmortem MRI, and microscopic evaluation in a fetus with hypoplastic left heart syndrome terminated at 15+5 weeks of gestation, showing the left ventricle was smaller than the right ventricle significantly and the arrows showed mitral valve atresia.

Figure 4

Discordant findings of postmortem MRI and autopsy compared with prenatal ultrasound. (a) A fetus presented with severe tricuspid regurgitation on the color Doppler imaging in the first trimester and was terminated at 17+6 weeks of gestation for Trisomy 21 (Case 15 in Table 2); (b) Four-chamber view showed the atrioventricular septal defect (AVSD) (black arrow) on the postmortem MRI; (c) Microscopic evaluation (H&E) assessed the AVSD.

Figure 5

Discordant findings of postmortem MRI and autopsy compared with prenatal ultrasound. A fetus (Case 17 in Table 2) was detected as transposition of the great arteries (a) and was terminated at 17+6 weeks of gestation for Trisomy 18. The postmortem MRI showed both aortic artery and pulmonary artery arose entirely from the right ventricle with the aorta to the right and anterior to the pulmonary artery. (b,c) The autopsy confirmed the diagnosis of double-outlet right ventricle (d,e).

Figure 6

Discordant findings of postmortem MRI compared with prenatal ultrasound. (a) A fetus presented with an AVSD on the four-chamber view and was terminated at 13+0 gestational weeks (Case 1 in Table 2). Postmortem MRI showed intact atrioventricular septal (b) and left ventricle outflow tract showed malalignment ventricular septal defect (c, black arrow).

Figure 7

(a,b) A fetus terminated at 13+5 weeks of gestation and diagnosed as AVSD and suspected of great vessels malformation (Case 2 in Table 2); (c,d) Post-mortem MRI showing the AVSD at the four-chamber view and an overriding aorta at left ventricle outflow tract view.

Figure 8

(a,b) A fetus presented with a smaller left ventricle on the four-chamber view and a larger pulmonary artery diameter than that of the aorta (1.5 vs. 0.7 mm) at the three-vessel view in the first trimester and was terminated at 12+6 weeks of gestation for Turner syndrome (Case 12 in Table 2). (c,d) Postmortem MRI showed a normally connected heart with the crossing of the great vessels and a larger pulmonary artery diameter than that of the aorta (0.65 vs. 0.37 mm).