B. Deloison

Laser therapy for twin-to-twin transfusion syndrome (TTTS).

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins including twin‐to‐twin transfusion syndrome. The diagnosis is well established in overt clinical forms with the association of polyuric polyhydramnios and oliguric oligohydramnios. The best treatment of cases presenting before 26 weeks of gestion is fetoscopic laser ablation of the intertwin anastomoses on the chorionic plate. Although subjected to subtle variations, the core technique follows robust guidelines which could help understanding and acquiring the required skills and experience to perform this procedure. However appropriate and tailored hands‐on training and appropriate perinatal set‐up are critical not only for surgical management but also for the follow‐up and management of related complications. Copyright

Active management of selective intrauterine growth restriction with abnormal Doppler in monochorionic diamniotic twin pregnancies diagnosed in the second trimester of pregnancy.

This study aims to compare outcomes of active management of monochorionic diamniotic twin pregnancies complicated with severe intrauterine growth restriction (IUGR) of one twin before 24 weeks with continuous or intermittent absent or reversed end‐diastolic flow (AREDF) in the umbilical artery, with or without twin‐to‐twin transfusion syndrome (TTTS).

Fetoplacental Oxygenation in an Intrauterine Growth Restriction Rat Model by Using Blood Oxygen Level–Dependent MR Imaging at 4.7 T

PURPOSE To investigate blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging in an intrauterine growth restriction (IUGR) rat model as a noninvasive in vivo tool to evaluate the response of the fetoplacental units (FPUs) to oxygenation MATERIALS AND METHODS All procedures were approved by the animal care committee. The study was performed between February and July 2010. The IUGR model based on the ligation of the left uterine vascular pedicle at embryonic day 17 of gestation was validated by weighing placentas and fetuses after MR imaging. FPUs in the left and right uterine horns were IUGR cases and controls, respectively. A small-animal 4.7-T MR imager was used. Multiple gradient-echo sequence (repetition time msec/echo time msec, 800/1.8-49.8) was performed at embryonic day 19. T2* relaxation time was measured before and after maternal hyperoxygenation for live FPUs in placenta, fetal liver, and brain. The effect of hyperoxygenation on BOLD MR imaging was analyzed with change in T2* between hyperoxygenation and ambient air. After dissection, live fetuses from both horns were identified and weighed. Changes in T2* were compared based on Student t tests. A mixed model was used to compare BOLD effect among horns and organs. RESULTS Sixteen rats were studied. There was a significant fetal weight decrease in the IUGR FPUs (-21.9%; P < .001). Change in T2* differed significantly between IUGR cases and controls for placenta (5.25 msec vs 11.25 msec; P < .001) and fetal brain (3.7 msec vs 7.17 msec; P = .02), whereas there was no significant difference in the fetal liver (2.72 msec vs 3.18 msec; P = .47). CONCLUSION BOLD MR imaging at 4.7 T can be used to evaluate the response to oxygenation in normal and IUGR FPUs. This technique has a potential role in the assessment of human pregnancy.

Dynamic contrast-enhanced magnetic resonance imaging: definitive imaging of placental function?

The placenta constitutes a complex circulatory interface between the mother and fetus, but the relationship between the maternal and fetal circulation is still very difficult to study in vivo. There is growing evidence that magnetic resonance imaging (MRI) is useful and safe during pregnancy, and MRI is increasingly used for fetal and placental anatomical imaging. MRI functional imaging is now a modern obstetric tool and has the potential to provide new insights into the physiology of the human placenta. Placental perfusion has been studied during the first pass of an MR contrast agent, by arterial spin labeling, diffusion imaging, T1 and T2 relaxation time measurement using echo-planar imaging, and by a combination of magnetization transfer with established stereological methods. The BOLD (blood oxygen level-dependent) effect offers new perspectives for functional MRI evaluation of the placenta.

SPIO-enhanced magnetic resonance imaging study of placental perfusion in a rat model of intrauterine growth restriction

Please cite this paper as: Deloison B, Siauve N, Aimot S, Balvay D, Thiam R, Cuenod C, Ville Y, Clement O, Salomon L. SPIO‐enhanced magnetic resonance imaging study of placental perfusion in a rat model of intrauterine growth restriction. BJOG 2012;119:626–633.

Measurement of placental perfusion by dynamic contrast-enhanced MRI at 4.7 T.

Purpose:The purposes of this study were to develop quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) at 4.7 T for perfusion measurement and to evaluate the ability of this technique to distinguish between low and normal levels of placental perfusion in a controlled rat model. Materials and Methods:This study was approved by the animal care committee. Poor placental perfusion in the left uterine horn was achieved by ligation of the left uterine vascular pedicle on the 17th embryonic day in 12 pregnant rats. High–temporal resolution DCE-MRI (<1 second) was performed on the 19th embryonic day. Single-compartment analysis was used to calculate placental blood flow (F), volume fraction (Vb), and time delay (Dt) for each placenta and its 2 layers in both uterine horns. Mixed regression analysis was used to compare parameters between the ligated and nonligated horn and between placental layers. Results:We examined 53 placentas: 11 on the ligated side and 42 on the control side. On the control side, the mean (SD) values were 115 (72) mL/min per 100 mL for F, 38.6% (11.7%) for Vb, and 5.5 (5.3) seconds for Dt.Placental blood flow was significantly lower on the ligated side (66 [30] mL/min per 100 mL; P = 0.001).Placental blood flow and Vb were significantly higher, whereas Dt was significantly lower in the inner layer than in the outer layer in both horns (P=0.0001). Conclusions:Quantitative analyses of perfusion are feasible with DCE-MRI at 4.7 T.Dynamic contrast-enhanced magnetic resonance imaging can differentiate between low and normal levels of placental perfusion in a rat model. Dynamic contrast-enhanced magnetic resonance imaging at 4.7 T is a promising preclinical tool for quantifying and monitoring microvascularization.

Outcomes of fetuses with small head circumference on second‐trimester ultrasonography

We examined the outcomes of pregnancies in which the fetal head circumference (HC) was below the 5th centile at the routine second‐trimester scan.

Assessment of human placental perfusion by intravoxel incoherent motion MR imaging

Abstract Purpose: To provide functional information on the human placenta, including perfusion, and diffusion, with no contrast agent injection, and to study correlations between intravoxel incoherent motion (IVIM) placental parameters and fetal growth. Materials and methods: MRI was performed in women undergoing legal termination of pregnancy at 17–34 weeks, including a 4-b-value and 11-b-value DW sequences. The apparent diffusion coefficient (ADC), the restricted diffusion coefficient (D), the pseudoperfusion coefficient (D*), and the perfusion fraction (f) were calculated. Their relationships with gestational age, Z-scores for fetal and placental weight were evaluated by means of regression analysis. Logistic regression analysis was used to assess the ability of IVIM parameters to predict/detect intrauterine growth retardation (SGA). Results: Fifty-five pregnant women, including nine cases of SGA (16%), were included in the study. The ADC (n = 55) showed a quadratic correlation with gestational age (p < .001) and a linear correlation with the fetal weight Z-score (p = .02). Mean ADC values were significantly different between normally growing and SGA fetuses (2.37 ± 0.25 versus 2.29 ± 0.33 10−3.mm2.s−1, p=.048). The perfusion fraction f (n = 23) showed a quadratic correlation with gestational age (p = .017) and a linear correlation with the fetal weight Z − score (p = .008). Mean f values differed significantly between normally growing and SGA fetuses (42.55 ± 9.30% versus 27.94 ± 8.76%, p = .002). The receiver operating characteristics (ROC) curve for f to predict SGA was produced (area under the ROC curve = 0.9). Conclusions: The observed association between f and fetal weight suggests that fMRI could be suitable for studying placental insufficiency and for identifying risk of SGA.

IRM placentaire : physiologie et pathologie

The placenta is essential for fetal development but its in vivo study, including the study of placental perfusion is still very limited to date. MRI is a safe examination that offers new perspectives for the study of placental function that is altered in many conditions (IUGR, preeclampsia…) and placental anatomy (placenta accreta…). The different MRI sequences (DCE, IVIM, BOLD, ASL…) are new tools that may soon allow us to assess precisely placental function and anatomy, in vivo and non-invasively.

P13.01: Prenatal corpus callosum measurement: biometry 2nd and 3rd trimester

Objectives: We compared morphological parameters of urogenital hiatus in women after acute and elective Caesarean Section (CS). Methods: This is an open, prospective and non randomised study. All patients undergo 3D/4D ultrasound of the pelvic floor 6 weeks post partum, women are examined in supine position, after voiding. Patients are examined at rest, during pelvic muscle contraction and upon Valsava. Volumes are analyzed offline. Following parameters are measured: size of the urogenital hiatus (UGH, cm2) and parameter H (cm, measured as distance between the urethrovesical junction – UVJ and horizontal line going through the lower edge of the symphysis pubis). Results: We obtained data from 130 patients. 31 patients (23.8%) underwent elective CS, 99 patients (76.2%) delivered by acute CS. There was no statistically significant difference in measured parameters between patients after acute or elective surgery and there also wasn’t any difference when comparing acute CS in the first or second stage of labour. In patients after elective CS, mean UGH at rest was 11.92 (min. 7.67, ma. 17.68), H at rest was 3.2 (min. 2.4, max. 4.6), during contraction mean UGH was 10.56 (min. 6.92, max. 15.22), mean H was 3.56 (min. 2.72, max. 4.68) and upon Valsava mean UGH was 13.89 (min. 9.1, max. 18.74), mean H was 2.52 (min. 0.79, max. 3.51). In patients after acute CS mean UGH at rest was 12.3 (min. 7.79, max. 19.79), mean H was 3.26 (min. 2.1, max. 5), during contraction mean UGH was 10.5 (min. 6.98, max. 16.98), mean H was 3.58 (min. 2.28, max. 5.71) and upon Valsava mean UGH was 15.53 (min. 8.,22, max. 27.07) and mean H was 2.46 (min. 0, max. 4.18). Conclusions: There is no statistically significant difference in urogenital hiatus parameters measured by 4D ultrasound when comparing data from patients after elective and acute CS. We found no avulsion of the levator in women after CS.