OC12.08: Conotruncal anomalies detected at early fetal echocardiography

Abstract

Objectives: To evaluate the feasibility of Doppler-ultrasound (DUS) gated four-dimensional (4D) flow magnetic resonance imaging (MRI) in the human fetus at 3 Tesla. Methods: 4D flow MRI measurements of the thoracic aorta were acquired in six healthy fetuses (gestational week 30-35) at 3T (Philips, Ingenia). Fetal cardiac gating was performed using an MR-compatible Doppler-ultrasound sensor. 4D flow MRI was performed in parasagittal orientation using compressed sensing (sense factor = 4) and free maternal breathing. For each 4D dataset, fetal aortic blood flow was visualised and quantified using dedicated software (GTFlow 3.2, GyroTools LLC, Zurich, Switzerland). Results: 4D flow MRI was successfully performed in 5/6 (83%) fetuses. One dataset could not be analysed due to fetal movements and inadequate image quality. Blood flow of the thoracic aorta was successfully visualised in the remaining five fetuses including foramen ovale and ductus arteriosus. The transverse diameter of the descending aorta was 7.8 mm (± 1.2 mm). Time-velocity curves based on 4D flow measurements demonstrated typical arterial blood flow patterns with early systolic peaks and low positive diastolic flow. Mean blood flow velocity in the descending aorta was 24 ml/s (± 4 ml/s). Conclusions: Direct cardiac Doppler-ultrasound gating allowed successful 4D flow MRI acquisition of the thoracic aorta in the human fetuses at 3 Tesla. DUS-gated 4D flow MRI of the fetal thoracic aorta visualised patterns of hemodynamics and allowed blood flow quantifications. The feasibility of DUS-gated 4D flow MRI could be demonstrated, yet the diagnostic performance of this technique, e.g. regarding congenital cardiovascular disease, is still unclear and requires further investigation. DUS-gated 4D flow MRI of the fetal heart and great thoracic vessels might potentially provide a valuable adjunct to echocardiography in the diagnosis of congenital cardiovascular disease.