Purpose To develop and validate a method for accelerated time‐resolved imaging of the fetal heart using a combination of compressed sensing (CS) and metric optimized gating (MOG). Theory and Methods Joint optimization of CS and MOG reconstructions was used to suppress competing artifact from random undersampling and ungated cardiac motion. Retrospectively and prospectively undersampled adult and fetal data were used to validate the proposed reconstruction algorithm qualitatively based on visual assessment, and quantitatively based on reconstruction error, blur, and MOG timing error. Results Excellent agreement was observed between the fully sampled and retrospectively undersampled reconstructions, up to an undersampling factor of four. Visually, differences between ECG and MOG reconstructions of adult data were negligible. This was consistent with quantitative comparisons of reconstruction error (RMSEECG = 0.07–0.13; RMSEMOG = 0.08–0.13), and image blur (BECG = 1.03–1.20; BMOG = 1.03–1.20). The calculated MOG timing error (2–42 ms) was comparable to the acquired temporal resolution (∼60 ms). Quantitative evaluation of retrospectively undersampled (R = 2–8) fetal data (RMSEMOG = 0.06–0.12; BMOG = 1.04–1.27) was comparable to the adult volunteer results. Conclusion CS‐MOG for dynamic imaging of the fetal heart was developed and validated. Using CS‐MOG, images were obtained up to four times faster than conventional acquisitions. Magn Reson Med 77:2125–2135, 2017. © 2016 International Society for Magnetic Resonance in Medicine

Representative Rvent, FVLcc, and QN maps overlaid on the registered GRE image (grayscale) for participant 11 (top) and participant 07 (bottom). Yellow arrows highlight regions of low FVLcc and QN in the left lung. RVent = regional ventilation; FVLcc = flow volume loop cross correlation; QN = normalized perfusion. by Brandon Zanette et al. (1696–1707)

Magnetic resonance imaging (MRI) assessment of fetal blood oxygen saturation (SO 2 ) can transform the clinical management of high-risk pregnancies affected by fetal growth restriction (FGR). Here, a novel MRI method assesses the feasibility of identifying normally grown and FGR fetuses in sheep and is then applied to humans. MRI scans are performed in pregnant ewes at 110 and 140 days (term = 150d) gestation and in pregnant women at 28 +3 ± 2 +5 weeks to measure feto-placental SO 2 . Birth weight is collected and, in sheep, fetal blood SO 2 is measured with a blood gas analyzer (BGA). Fetal arterial SO 2 measured by BGA predicts fetal birth weight in sheep and distinguishes between fetuses that are normally grown, small for gestational age, and FGR. MRI feto-placental SO 2 in late gestation is related to fetal blood SO 2 measured by BGA and body weight. In sheep, MRI feto-placental SO 2 in mid-gestation is related to fetal SO 2 later in gestation. MRI feto-placental SO 2 distinguishes between normally grown and FGR fetuses, as well as distinguishing FGR fetuses with and without normal Doppler in humans. Thus, a multi-compartment placental MRI model detects low placental SO 2 and distinguishes between small hypoxemic fetuses and normally grown fetuses.