Foetal 4D flow cardiac magnetic resonance for advanced diagnostics of congenital heart disease: a prospective cohort study

Foetal circulation undergoes complex changes in congenital heart disease (CHD) that are challenging to assess with foetal echocardiography. This study aimed to assess clinical feasibility and diagnostic value of 4D flow cardiovascular magnetic resonance (CMR) in foetal CHD.

Pregnant women in advanced third trimester pregnancy with foetal CHD were prospectively recruited for foetal CMR between August 2021 and November 2024. CMR protocol included cine and 4D time-resolved PC acquisitions. 4D flow data were evaluated for additional diagnostic information beyond cine imaging. Postnatal examination reports were used to confirm CMR findings. Net flow was quantified in the ascending aorta, distal aortic arch, main pulmonary artery, ductus arteriosus, and descending aorta and normalized to combined ventricular output (CVO). Student’s t-test and analysis of variance with Tukey post hoc test were applied. Among 77 participants, 4D flow was of diagnostic quality in 62 (81%) foetuses [11/62 (18%) without CHD, 51/62 (82%) with CHD]. Comparison of net flow distributions revealed significant differences between foetuses without CHD and those with hypoplastic left heart complex (HLHC), dextro-transposition of the great arteries, and coarctation of the aorta. CVO was higher in normal foetal circulation compared with CHD (6.4 ± 1.5 mL vs. 5.1 ± 1.9 mL, P = 0.049). 4D flow provided diagnostic findings beyond cine imaging in 26/51 (51%) foetuses with CHD (e.g. retrograde aortic perfusion in HLHC) that were confirmed postnatally.

Foetal 4D flow CMR characterizes flow patterns and provides relevant diagnostic information beyond cine imaging for prenatal CHD assessment.