Prenatal detection of fetal growth restriction by fetal femur volume: efficacy assessment using three-dimensional ultrasound

A computer-aided method based on geometrical texture features for a precocious detection of fetal Hydrocephalus in ultrasound images

BACKGROUD

Hydrocephalus is the most common anomaly of the fetal head characterized by an excessive accumulation of fluid in the brain processing. The diagnostic process of fetal heads using traditional evaluation techniques are generally time consuming and error prone. Usually, fetal head size is computed using an ultrasound (US) image around 20-22 weeks, which is the gestational age (GA). Biometrical measurements are extracted and compared with ground truth charts to identify normal or abnormal growth.

METHODS

In this paper, an attempt has been made to enhance the Hydrocephalus characterization process by extracting other geometrical and textural features to design an efficient recognition system. The superiority of this work consists of the reduced time processing and the complexity of standard automatic approaches for routine examination. This proposed method requires practical insidiousness of the precocious discovery of fetuses' malformation to alert the experts about the existence of abnormal outcome. The first task is devoted to a proposed pre-processing model using a standard filtering and a segmentation scheme using a modified Hough transform (MHT) to detect the region of interest. Indeed, the obtained clinical parameters are presented to the principal component analysis (PCA) model in order to obtain a reduced number of measures which are employed in the classification stage.

RESULTS

Thanks to the combination of geometrical and statistical features, the classification process provided an important ability and an interesting performance achieving more than 96% of accuracy to detect pathological subjects in premature ages.

CONCLUSIONS

The experimental results illustrate the success and the accuracy of the proposed classification method for a factual diagnostic of fetal head malformation.

Continuous objective recording of fetal heart rate and fetal movements could reliably identify fetal compromise, which could reduce stillbirth rates by facilitating timely management

Stillbirth currently affects approximately 1 in every 200 pregnancies in the United Kingdom. Fetuses may exhibit signs of compromise as part of a stress response before stillbirth, including reduced fetal movements (RFM) and fetal heart rate (FHR) alterations. At present, and despite widespread use, current fetal monitoring is not associated with a reduction in perinatal mortality rate (PMR) as signs of fetal compromise are not adequately detected. This may be attributed to inaccuracies resulting from manual interpretation of results or subjective assessment of fetal activity. In addition, signs of compromise often occur only hours or days before fetal death, so may be missed by current monitoring methods, which are performed intermittently. A significant consideration is that correct identification of these signs and consequent intervention can result in the delivery of a healthy baby, thus preventing stillbirth. A hypothesis is presented, proposing prompt detection of fetal compromise with the use of 24-hour continuous objective fetal monitoring. With focus placed on obtaining long-term FHR and fetal movement data, prior interest has been found in developing devices for this purpose. However, introduction into clinical practice has not been achieved. Investigation of the hypothesis will begin with the design of a device to record the mentioned parameters, followed by an appropriate validation process. Should development and testing be successful, an eventual comparison in PMR with the use of continuous fetal monitoring vs current monitoring would address the hypothesis. It is suggested that a timely yet reliable indication of fetal wellbeing obtained via long-term monitoring would allow prompt and appropriate obstetric intervention and consequently reduce PMR.

Evaluation and comparison of current fetal ultrasound image segmentation methods for biometric measurements: a grand challenge

This paper presents the evaluation results of the methods submitted to Challenge US: Biometric Measurements from Fetal Ultrasound Images, a segmentation challenge held at the IEEE International Symposium on Biomedical Imaging 2012. The challenge was set to compare and evaluate current fetal ultrasound image segmentation methods. It consisted of automatically segmenting fetal anatomical structures to measure standard obstetric biometric parameters, from 2D fetal ultrasound images taken on fetuses at different gestational ages (21 weeks, 28 weeks, and 33 weeks) and with varying image quality to reflect data encountered in real clinical environments. Four independent sub-challenges were proposed, according to the objects of interest measured in clinical practice: abdomen, head, femur, and whole fetus. Five teams participated in the head sub-challenge and two teams in the femur sub-challenge, including one team who tackled both. Nobody attempted the abdomen and whole fetus sub-challenges. The challenge goals were two-fold and the participants were asked to submit the segmentation results as well as the measurements derived from the segmented objects. Extensive quantitative (region-based, distance-based, and Bland-Altman measurements) and qualitative evaluation was performed to compare the results from a representative selection of current methods submitted to the challenge. Several experts (three for the head sub-challenge and two for the femur sub-challenge), with different degrees of expertise, manually delineated the objects of interest to define the ground truth used within the evaluation framework. For the head sub-challenge, several groups produced results that could be potentially used in clinical settings, with comparable performance to manual delineations. The femur sub-challenge had inferior performance to the head sub-challenge due to the fact that it is a harder segmentation problem and that the techniques presented relied more on the femur's appearance.

Fusion of 3D ultrasound images of the fetal femur improves boundary definition and volume measurement

OBJECTIVE

To combine multiple 3D volumes of the same fetal femur into one composite image data set using image registration and wavelet-based fusion. Fused and single data sets were compared in terms of image quality and femur volume (FV) measurement repeatability.

METHOD

In healthy pregnant volunteers, six volumes of the same femur were acquired and fused into a composite data set. Image quality scores were given to the fused and single data sets by an independent assessor in a blinded fashion; repeatability of FV measurement was assessed using coefficients of variation (CV), intraclass correlation coefficients (ICC) and Bland-Altman plots.

RESULTS

Fusion was successful in 24 out of 25 cases. Median image quality score was 7/10 in fused data sets, compared to 6/10 in single data sets (p = 0.096). Repeatability of FV measurement was better in fused data sets (intraobserver CV 4.6% and ICC 0.987; interobserver CV 4.9%, ICC 0.985) compared to single ones (intraobserver CV 5.8%, ICC 0.977; interobserver CV 10.0%, ICC 0.931). The measured FV was significantly higher in fused data sets (mean FV 1.7 vs. 1.3 ml, p < 0.001).

CONCLUSION

Image registration and wavelet-based fusion can improve image quality and FV repeatability; it also results in an increased FV measurement.

The effect of maternal vitamin D concentration on fetal bone

CONTEXT

Vitamin D deficiency during pregnancy may be associated with suboptimal fetal growth, but direct evidence is lacking.

OBJECTIVES

The 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.

DESIGN, SETTING, AND PARTICIPANTS

A 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.

MAIN OUTCOME MEASURES

We performed ultrasound measurements of the fetal femur.

RESULTS

In 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.

CONCLUSION

Using 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.

Discordant twins: diagnosis, evaluation and management

Approximately 16% of twin gestations have discordance of at least 20%. We identified 14 risk factors for divergent growth that can be categorized as maternal, fetal, or placental. Determination of chorionicity and serial ultrasound evaluation with a high index of suspicion for divergent growth is required for the diagnosis and stratification of risk. The highest reported likelihood ratio for detection of discordance was 5.9 during the first trimester examination and 6.0 for the second trimester. Although our ability to identify discordant twins is limited, once suspected and at viable gestational age, these pregnancies should have antepartum testing. Discordant growth alone is not an indication for preterm birth. Although there are multiple publications on the increased morbidity and mortality rates with discordant growth, there is a paucity of reports on how to manage them optimally and deliver them in a timely manner.

A review of fetal volumetry: the need for standardization and definitions in measurement methodology

Volume charts of fetal organs and structures vary considerably among studies. This review identified 42 studies reporting normal volumes, namely for fetal brain (n = 3), cerebellum (n = 4), liver (n = 6), femur (n = 2), lungs (n = 15), kidneys (n = 3) and first-trimester embryo (n = 9). The differences among median volumes were expressed both in percentage form and as standard deviation scores. Wide discrepancies in reported normal volumes make it extremely difficult to diagnose pathological organ growth reliably. Given its magnitude, this variation is likely to be due to inconsistencies in volumetric methodology, rather than population differences. Complicating factors include the absence of clearly defined anatomical landmarks for measurement; inadequate assessment and reporting of method repeatability; the inherent difficulty in validating fetal measurements in vivo against a reference standard; and a multitude of mutually incompatible three-dimensional (3D) imaging formats and software measuring tools. An attempt to standardize these factors would improve intra- and inter-researcher agreement concerning reported volumetric measures, would allow generalization of reference data across different populations and different ultrasound systems, and would allow quality assurance in 3D fetal biometry. Failure to ensure a quality control process may hamper the wide use of 3D ultrasound.

Soft tissue volume of upper arm in predicting small-for-gestational-age fetuses using three-dimensional ultrasound

PURPOSE

To assess the value of fetal soft tissue volume (STV) of the upper arm in predicting small-for-gestational-age (SGA) fetuses using three-dimensional (3D) ultrasound (US).

METHODS

We used 3D US to test the accuracy of fetal STV of the upper arm measurement in predicting SGA in a prospective cross-sectional study.

RESULTS

Fetal STV of the upper arm assessed by 3D US can differentiate SGA fetuses from appropriate-for-gestational-age (AGA) fetuses. Using the 5th percentile as the cutoff, the sensitivity of fetal upper arm STV in predicting SGA fetuses was 84.1%, specificity, 93.4%, positive predictive value, 71.1%, negative predictive value, 96.8%, and overall accuracy, 91.9%. In addition, the diagnostic accuracy of fetal arm STV was better than that of the biparietal diameter, abdominal circumference, and femur length.

CONCLUSION

Fetal STV of upper arm assessment by 3D US is a novel method to predict SGA fetuses.

Predicting fetal growth restriction with renal volume using 3-D ultrasound: efficacy evaluation

Early detection and management of fetal growth restriction (FGR) is very important in prenatal care and daily practice, because FGR fetuses may suffer increased risk of perinatal morbidity and mortality. Renal volume (RV) might be one of the important parameters of fetal growth. Yet, no prenatal assessment of fetal RV in FGR fetuses by 3-D ultrasound (US) has been reported. We undertook a prospective and cross-sectional study using quantitative 3-D US to assess the efficacy of fetal RV in predicting FGR. All fetuses were singletons and were followed-up to delivery to determine whether they had FGR complications. In total, 221 fetuses without FGR and 28 fetuses with FGR were included. Our results showed fetal RV assessed by 3-D US can differentiate fetuses with FGR from fetuses without FGR. The best predicting threshold for FGR is at the tenth percentile of fetal RV. Using the tenth percentile as the cutoff, the efficacy of fetal RV in predicting FGR was sensitivity 96.4%, specificity 95.9%, positive predictive value 75.0%, negative predictive value 99.5% and accuracy 96.0%, respectively. Fetal RV assessed by 3-D US can be applied to detect FGR prenatally. We believe fetal RV assessment using 3-D US is a useful test in detecting fetuses with FGR.