Aris T. Papageorghiou

Uterine artery Doppler in the prediction of adverse pregnancy outcome.

Purpose of review To review publications, published during the past year, that have examined uterine artery Doppler findings in women with adverse pregnancy outcome. Recent findings Almost two-thirds of stillbirths that occur in the early preterm period (up to 32 weeks) can be predicted by uterine artery Doppler at 23 weeks. First trimester screening studies have shown that an abnormal result increases the risk of subsequent fetal growth restriction, and such women are at particularly high risk when indices remain abnormal in the second trimester. Studies combining uterine artery Doppler with maternal serum markers have demonstrated that measurement of first-trimester maternal serum pregnancy-associated plasma protein A and free β human chorionic gonadotrophin improve sensitivities of second-trimester Doppler. As these are frequently measured in Down syndrome screening and they lend themselves in screening for pre-eclampsia. Women with abnormal first and second-trimester serum markers constitute a high-risk group. Maternal serum placental protein 13 remains a promising method for early screening, although a recent study suggests lower sensitivities than initially reported. Summary Uterine artery Doppler screening identifies women at high risk for developing adverse pregnancy outcomes. Detection rates may be increased and false positive rates reduced by combination with maternal characteristics or serum markers.

The Effect of Maternal Vitamin D Concentration on Fetal Bone

CONTEXTnVitamin D deficiency during pregnancy may be associated with suboptimal fetal growth, but direct evidence is lacking.nnnOBJECTIVESnThe aim of the study was to validate a method for fetal femur volume (FV) measurement using three-dimensional ultrasound and to detect correlations between FV and maternal vitamin D concentration.nnnDESIGN, SETTING, AND PARTICIPANTSnA novel method for assessing FV consists of three ultrasound measurements-femur length, proximal metaphyseal diameter (PMD), and midshaft diameter-and a volume equation; this was validated by comparing ultrasound to computed tomography measurements in six pregnancies after mid-trimester termination. This method was then applied in a cohort of healthy pregnant women participating in the Southampton Women Survey. Fetal three-dimensional ultrasound and maternal 25-hydroxyvitamin D [25(OH)D] levels were performed at 34 wk; dual-energy x-ray absorptiometry of the newborn was performed shortly after birth. Univariate and multiple linear regression analyses were performed between maternal characteristics and fetal outcomes.nnnMAIN OUTCOME MEASURESnWe performed ultrasound measurements of the fetal femur.nnnRESULTSnIn 357 pregnant participants, serum 25(OH)D correlated significantly with FV (P = 0.006; r = 0.147) and PMD (P = 0.001; r = 0.176); FV also demonstrated positive univariate correlations with maternal height (P < 0.001; r = 0.246), weight (P = 0.003; r = 0.160), triceps skinfold thickness (P = 0.013; r = 0.134), and a borderline negative effect from smoking (P = 0.061). On multiple regression, independent predictors of FV were the maternal height and triceps skinfold thickness; the effect of 25(OH)D on FV was attenuated, but it remained significant for PMD.nnnCONCLUSIONnUsing a novel method for assessing FV, independent predictors of femoral size were maternal height, adiposity, and serum vitamin D. Future trials should establish whether pregnancy supplementation with vitamin D is beneficial for the fetal skeleton, using FV and PMD as fetal outcome measures.

First trimester screening for preeclampsia.

Purpose of review Aspirin therapy from the first trimester of pregnancy may benefit women at high risk for preeclampsia. We review publications from the past year that examine first-trimester screening studies for preeclampsia. Recent findings For a false positive rate of 5%, first-trimester uterine artery Doppler studies will detect 50–65% of women who will develop severe preeclampsia (i.e. needing delivery before 35 weeks). Measurement of placental volume with three-dimensional ultrasound at 11–14 weeks detected 20% for a false positive rate of 10% in one study and further evaluation of this technique is needed. Maternal serum placental growth factor, vascular endothelial growth factor and soluble fms-like tyrosine kinase-1 have shown initial promise, but recent studies have shown no improvement in screening compared with using uterine artery Doppler alone. Placental protein 13 is the most promising serum marker and in combination with uterine Doppler may predict up to 90% of cases of severe preeclampsia for a false positive rate of 9%. Summary First-trimester uterine artery Doppler can identify over half of women who will develop preeclampsia. Detection rates may be increased by a combination of uterine artery Doppler with first-trimester maternal serum markers, especially placental protein 13. Such high-risk women may be the most likely to benefit from pharmacological intervention in future trials.

Integration of Local and Global Features for Anatomical Object Detection in Ultrasound

The use of classifier-based object detection has found to be a promising approach in medical anatomy detection. In ultrasound images, the detection task is very challenging due to speckle, shadows and low contrast characteristic features. Typical detection algorithms that use purely intensity-based image features with an exhaustive scan of the image (sliding window approach) tend not to perform very well and incur a very high computational cost. The proposed approach in this paper achieves a significant improvement in detection rates while avoiding exhaustive scanning, thereby gaining a large increase in speed. Our approach uses the combination of local features from an intensity image and global features derived from a local phase-based image known as feature symmetry. The proposed approach has been applied to 2384 two-dimensional (2D) fetal ultrasound abdominal images for the detection of the stomach and the umbilical vein. The results presented show that it outperforms prior related work that uses only local or only global features.

Effect of malaria on placental volume measured using three-dimensional ultrasound: a pilot study

BackgroundThe presence of malaria parasites and histopathological changes in the placenta are associated with a reduction in birth weight, principally due to intrauterine growth restriction. The aim of this study was to examine the feasibility of studying early pregnancy placental volumes using three-dimensional (3D) ultrasound in a malaria endemic area, as a small volume in the second trimester may be an indicator of intra-uterine growth restriction and placental insufficiency.MethodsPlacenta volumes were acquired using a portable ultrasound machine and a 3D ultrasound transducer and estimated using the Virtual Organ Computer-aided AnaLysis (VOCAL) image analysis software package. Intra-observer reliability and limits of agreement of the placenta volume measurements were calculated. Polynomial regression models for the mean and standard deviation as a function of gestational age for the placental volumes of uninfected women were created and tested. Based on these equations each measurement was converted into a z -score. The z-scores of the placental volumes of malaria infected and uninfected women were then compared.ResultsEighty-four women (uninfected = 65; infected = 19) with a posterior placenta delivered congenitally normal, live born, single babies. The mean placental volumes in the uninfected women were modeled to fit 5th, 10th, 50th, 90th and 95th centiles for 14-24 weeks gestation. Most placenta volumes in the infected women were below the 50th centile for gestational age; most of those with Plasmodium falciparum were below the 10th centile. The 95% intra-observer limits of agreement for first and second measurements were ± 37.0 mL and ± 25.4 mL at 30 degrees and 15 degrees rotation respectively.ConclusionThe new technique of 3D ultrasound volumetry of the placenta may be useful to improve our understanding of the pathophysiological constraints on foetal growth caused by malaria infection in early pregnancy.

Registration of 3d fetal brain US and MRI

We propose a novel method for registration of 3D fetal brain ultrasound and a reconstructed magnetic resonance fetal brain volumes. The reconstructed MR volume is first segmented using a probabilistic atlas and an ultrasound-like image volume is simulated from the segmentation of the MR image. This ultrasound-like image volume is then affinely aligned with real ultrasound volumes of 27 fetal brains using a robust block-matching approach which can deal with intensity artefacts and missing features in ultrasound images. We show that this approach results in good overlap of four small structures. The average of the co-aligned US images shows good correlation with anatomy of the fetal brain as seen in the MR reconstruction.

Where is my baby? A fast fetal head auto-alignment in 3D-ultrasound

Ultrasonography is the main modality for prenatal screening examination of the fetal central nervous system. Due to the variability of the position of the fetal brain relatively to the probe, getting through structures of interest requires both time and a high level of expertise. The method presented in this paper aims at helping the clinician navigate through the brain by automatically aligning the head in near real time (<; 1 s) in a 3D ultrasound volume. The alignment is obtained by defining a frame of reference based on the skull, the mid-sagittal plan and the orbits of the eyes; their signals remain strong and stable across acquisitions. They are detected by combining state-of-the-art techniques (random forests and template deformation). Our method has proven fast and accurate on a dataset of 78 volumes (19-24 gestational weeks): maximal alignment errors medians range from 5.1 to 5.8mm for the transcerebellar, transventricular and transthalamic planes.

Oriented feature-based coupled ellipse fitting for soft tissue quantification in ultrasound images

Soft tissue quantification from ultrasound (US) images is a challenging task due to signal dropouts, missing boundaries, and presence of speckle. Typically, intensity and intensity gradient-based methods do not suffice to obtain a good representation of the object of interest. Prior work has shown that local phase, derived from the monogenic signal, extracts structural information from US images, being contrast invariant. An oriented edge map can be derived from feature asymmetry, resulting from combining different scales of the local phase, and local orientation. This paper proposes a novel feature-based approach, based on a modified Hough transform framework, for the detection of coupled ellipses for soft tissue quantification in US images using oriented edge maps, derived from the monogenic signal. Quantitative and qualitative results are illustrated on US images of the fetal arm across gestation, the object of interest being the adipose tissue layer, which is an indicator of fetal nutrition.