Devasuda Anblagan

Maternal Smoking during Pregnancy and Fetal Organ Growth: A Magnetic Resonance Imaging Study

Objective To study whether maternal cigarette smoking during pregnancy is associated with alterations in the growth of fetal lungs, kidneys, liver, brain, and placenta. Design A case-control study, with operators performing the image analysis blinded. Setting Study performed on a research-dedicated magnetic resonance imaging (MRI) scanner (1.5 T) with participants recruited from a large teaching hospital in the United Kingdom. Participants A total of 26 pregnant women (13 current smokers, 13 non smokers) were recruited; 18 women (10 current smokers, 8 nonsmokers) returned for the second scan later in their pregnancy. Methods Each fetus was scanned with MRI at 22–27 weeks and 33–38 weeks gestational age (GA). Main outcome measures Images obtained with MRI were used to measure volumes of the fetal brain, kidneys, lungs, liver and overall fetal size, as well as placental volumes. Results Exposed fetuses showed lower brain volumes, kidney volumes, and total fetal volumes, with this effect being greater at visit 2 than at visit 1 for brain and kidney volumes, and greater at visit 1 than at visit 2 for total fetal volume. Exposed fetuses also demonstrated lower lung volume and placental volume, and this effect was similar at both visits. No difference was found between the exposed and nonexposed fetuses with regards to liver volume. Conclusion Magnetic resonance imaging has been used to show that maternal smoking is associated with reduced growth of fetal brain, lung and kidney; this effect persists even when the volumes are corrected for maternal education, gestational age, and fetal sex. As expected, the fetuses exposed to maternal smoking are smaller in size. Similarly, placental volumes are smaller in smoking versus nonsmoking pregnant women.

Measurement of fetal fat in utero in normal and diabetic pregnancies using magnetic resonance imaging

To assess the reliability of magnetic resonance imaging (MRI) to measure fetal fat volume in utero, and to study fetal growth in women with and without diabetes in view of the increased prevalence of macrosomia in the former.

PFM.39 Diagnostic accuracy of antenatal magnetic resonance imaging (MRI) to predict birth weight >90th centile or < 10th centile in the third trimester

Introduction Accurate diagnosis of disturbance in fetal size is needed to manage pregnancies and ensure optimal outcome. Conventionally ultrasound is used to estimate fetal weight (EFW) but diagnostic accuracy is poor. Methods Fetal MRI was performed on a 1.5 Tesla Philips Achieva scanner. Half Fourier Single Shot Turbo Spin-Echo (HASTE) and Balanced Fast Field Echo (bFFE) sequences of the uterine cavity were acquired. Fetal volume was measured by drawing a freehand mask around the fetus in contiguous slices using Analyse 9.0. To convert estimated fetal volume into MR_EFW the formula MR_EFW = 0.12 +1.031 × fetal_volume (1) was used. MR centiles were then calculated using the GROW customised centile calculator. The diagnostic accuracy of MRI in the detection of large (>90th centile: LGA) and small (<10th centile: SGA) for gestational age fetuses was calculated by comparison with actual birth-weight centiles. Results MRI was performed at an average gestational age of 35+0 weeks (SD ± 7 days) in 37 subjects. The average MR_EFW was 2554 (±437) g with a median MR_centile of 42.8. Mean gestational age at delivery was 39+3 weeks (±11 days) with a mean birth-weight of 3349 (±593) g and median birth-weight centile of 34.0. For LGA MRI had sensitivity: 83.3%, specificity: 96.6%, positive predictive value: 83.3% and negative predictive value: 96.6%. Corresponding values for SGA were 57.1%, 100%, 100%, 90.3%, respectively. For birth-weight <5th centile MRI had a sensitivity and specificity of 100%. Conclusion In this small study the diagnostic accuracy of MRI_EFW is superior to those quoted for USS_EFW (2, 3). References Baker PN, Johnson IR, Gowland PA, Hykin J, Harvey PR, Freeman A, et al. Fetal weight estimation by echo-planar magnetic resonance imaging. Lancet. 1994;343(8898):644–5 Chauhan SP, Cole J, Sanderson M, Magann EF, Scardo JA. Suspicion of intrauterine growth restriction: Use of abdominal circumference alone or estimated fetal weight below 10%. J Matern Fetal Neonatal Med. 2006;19(9):557–62 Coomarasamy A, Connock M, Thornton J, Khan KS. Accuracy of ultrasound biometry in the prediction of macrosomia: a systematic quantitative review. BJOG. 2005;112(11):1461–6

MRI for the assessment of placental blood flow in diabetic pregnancies

Introduction Optimal placental blood flow is essential for adequate materno-fetal nutrient exchange and a successful gestation. In maternal diabetes the placenta is often large with abnormal vascular development. To date, it has not been possible to study placental blood flow in detail, but MRI potentially provides such a technique. Aims To compare blood flow within the placenta in diabetic and control pregnancies using MRI. Methods Six women with diabetes and six controls had MRI scans at 24–26 weeks. A 1.5 T Philips Achieva MRI scanner was used. The IVIM sequence was respiratory gated, standard diffusion pulsed spin echo sequence acquired with five transverse slices encompassing the placenta at 12 b values, repeated five times. Analysis was performed to calculate the fractional moving blood volume (f, range 0–1) in each voxel of the entire placenta. Results The mean value of f in the two groups was similar; control (0.37) and diabetic (0.34). The women with diabetes had wider distributions of f with a lower mode (0.26 vs 0.32, p=0.04) and a borderline increased fraction of voxels with very high perfusion (f >0.8) at 4.1% vs 2.5% in controls (p=0.06). Conclusions We have for the first time antenatally demonstrated a difference in the distribution of placental blood flow in women with diabetes using MRI. It is possible that the high velocity blood flow observed in some intervillous spaces is of pathological significance. MRI provides a potentially valuable tool for the investigation of placental blood flow.

OC10.03: MRI assessment of regional fractional moving blood volume within the placenta

R. Deshpande1,2, D. Anblagan4, N. W. Jones1,2, N. Raine-Fenning1, G. Bugg2, P. Mansell3, P. Gowland4, L. Leach3 1School of Clinical Sciences, Division of Human Development, University of Nottingham, Nottingham, United Kingdom; 2Deparment of Obstetrics & Gynecology, Queens Medical Centre, Nottingham, United Kingdom; 3School of Biomedical Sciences, University of Nottingham, Nottingham, United Kingdom; 4Sir Peter Mansfield MRI Centre, University of Nottingham, Nottingham, United Kingdom