Impact of maternal positioning on maternal comfort and fetal magnetic resonance imaging quality in a 75-cm bore system

Objectives To compare maternal comfort between the supine and left lateral positions during fetal MRI and to assess fetal brain image quality with a conventional body array coil vs. a super-flexible coil on a 75-cm bore system. Methods In this prospective study, 50 women with singleton pregnancies (gestational age 25–36 weeks) referred for suspected fetal brain abnormalities underwent MRI on a 75-cm bore 3.0-T system. Each was scanned in both the supine and left lateral positions (order randomized) and rated comfort for each on a five-point Likert scale. Fetal brain images were analysed as three within-subject conditions: supine with conventional coil, supine with super-flexible coil, and left lateral with super-flexible coil. Image quality was assessed subjectively and objectively using repeated-measures analyses. Results Comfort scores were higher in the left lateral position than supine (4.2±0.8 vs. 3.8±0.9; p=0.031), particularly in late pregnancy. Subjective image quality did not differ significantly among conditions. In the primary positional contrast (super-flexible coil held constant), the left lateral position yielded significantly higher SNR in 17 of the 20 brain regions and higher CNR in six of the eight regions (all q <0.05 after false-discovery-rate correction), with differences most pronounced in late pregnancy (15 of 28 metrics remained significant after correction in the late-pregnancy subgroup vs. none in mid-pregnancy). Conclusions On a 75-cm bore system, the left lateral position improves maternal comfort, especially in late pregnancy, without compromising image quality; combined with a super-flexible coil, it may optimize fetal brain image quality.