OC02.04: Premature obstruction of the foramen ovale detected in fetal life—a single centre experience

Abstract

Objectives: To assess blood flow measurements of the fetal aorta performing cardiac MRI using a newly developed MR compatible Doppler-ultrasound device for triggering of the fetal heart in utero and to compare them with ultrasound studies in a sheep model. Methods: Four pregnant sheep carrying singleton fetuses (123 days gestational age) underwent ultrasound examination for determination of blood flow velocity in the fetal aorta descendens. The ewes were then anesthetized to undergo fetal MRI examination on a 1.5 T imager. A newly developed MR-compatible Doppler-ultrasound sensor was placed on the abdomen of the ewe, above the fetal heart and fixed with a belt. The recorded signal of the fetal heart was transferred to the ECG trigger unit of the MR scanner and used for cardiac triggering. Blood flow velocity measurements of the fetal aorta descendens were performed and compared to ultrasound measurements. Mean values and peak velocities were calculated. Results: Triggering of the fetal heart rate was possible in all examinations. Using the trigger signal excellent MR images of the fetal heart and high quality flow measurements of the fetal aorta were obtained. Comparison of both methods revealed no significant differences with mean peak flow velocities of 60 cm/s (±3.4) and 62 cm/s (±9.2). Conclusions: Blood flow measurements of the fetal aorta were successfully performed using the newly developed MR-compatible Doppler-ultrasound device for fetal cardiac triggering in a sheep model, revealing no significant differences compared to fetal ultrasound examination. The newly developed Doppler-ultrasound device for triggering fetal cardiovascular MRI enables precise intrauterine fetal blood flow measurements and might be an alternative to fetal ultrasound.