Comparison of 2D and 3D oxygen-enhanced MRI of the placenta.

Twelve subjects were recruited from St Mary’s Hospital, Manchester, following written informed consent (ethical approval REC:14/NW/0195 and 19/NW/0177) between 1st January 2018 to 31st December 2019.<br><br>Subjects were scanned using a 1.5T Philips Achieva MRI scanner (Philips Medical Systems Best, NL) whilst supine with a left lateral tilt, to reduce aortocaval compression by the gravid uterus. A cardiac receiver coil was placed on the abdomen, covering the entire uterus. Non-rebreathing masks (Intersurgical, Wokingham, UK) delivered medical air or 100% oxygen at a flow rate of 15 L/min to the subjects and respiratory triggering was used to minimise motion from maternal breathing.<br><br>T2-weighted structural scans were used to determine the position of the placenta and plan the oxygen-enhanced MRI (OE-MRI) slices. Two inversion recovery OE-MRI protocols were performed: a 3D turbo-spin echo with half Fourier acquisition (3D-HASTE) for full placental coverage and a 2D turbo-spin echo (2D-TSE), as used in previous studies. The single 2D slice positioned perpendicular to the placenta at the level of the cord insertion. The orientation of the 3D-HASTE matched that of the 2D-TSE. For both OE-MRI protocols a T1 map was calculated using a set of inversion recovery images, followed by a dynamic series of T1-weighted images during which the gas supply to the subject is switched from medical air (21%) to 100% oxygen in order to determine deltaR1.<br>To request access to data please email: [e-mail]