Birth weight prediction by Lee formula based on fractional thigh volume in term pregnancies – is it helpful?

IntroductionUltrasonographic estimation of fetal weight (EFW) is a standard obstetrical procedure in daily clinical practice. Formulas for calculating EFW most commonly are a combination of two-dimensional measurements. A relatively new approach is the use of three-dimensional measurements such as fractional thigh volume (TVol) incorporated into specific regression equations. The objective of this study was to compare the Lee formula based on three-dimensional ultrasonographic TVol in the estimation of fetal weight before delivery in term pregnancies to the Hadlock I formula.Material and methods2D/3D abdominal ultrasonography was performed in 104 women, 37–41 gestational weeks, and measurements of biparietal diameter, head circumference, abdomen circumference, and femur length, TVol were taken. Using these measurements, we compared the Lee to the Hadlock formulas in EFW. The timing of procedures was measured in 20 randomly chosen patients by an independent observer.ResultsMean percentage errors of formulas, Lee vs. Hadlock, were 2.13 ±9.31% vs. –2.02 ±8.79%, (p = 0.001). There was no statistically significant difference in median absolute percentage errors between the two formulas (6.09% vs. 6.10%, p = 0.56). The proportion of newborns with estimated birth weights (BW) within ±10% of actual BW was not significantly different between the two formulas (73% vs. 71%, p = 0.11). There was a significant difference in the proportion of the newborns with estimated BW within ±5% (33% vs. 42%, p = 0.000006). Statistical measurements for test performance in detecting fetuses with BW ≥ 4000 g were sensitivity 85% vs. 60%, specificity 88% vs. 96%, and accuracy 88% vs. 89%. There was no significant difference in the time to perform the measurements (69 s for Lee formula vs. 58 s for Hadlock formula, p = 0.16).ConclusionsThigh volume measurement incorporated into the Lee single parameter formula is comparable to the Hadlock I formula in terms of accuracy in predicting fetal weight before delivery. There was no significant difference in the time needed for taking necessary measurements between the two groups.Key words: fetal weight, biometry, ultrasonography, three-dimensional models     

Application of obstetric ultrasound to determine the most suitable parameters for the aging of formalin-fixed human fetuses using manual measurements

The aim of this study was to find the most suitable manual measurements to estimate the age of preserved fetuses. A new technique was used to make successful ultrasonic measurements on 86 out of 100 preserved fetuses under conditions simulating the intrauterine environment. The ultrasonographic images of the preserved specimens were very similar to those of live fetuses. Ultrasonic measurements of standard parameters, and the ages derived from them, were computed directly by the ultrasound scanning machine. Manual measurements were made of the same parameters using established techniques and standard tables for estimating fetal age. The measurements and the ages obtained for each parameter by the two techniques were statistically compared using the limits of agreement (Bland and Altman, 1986). Of the manual measurements used in the estimation of fetal age, foot length was found to be the most suitable parameter for practical use. Biparietal diameter was equally good, but the head circumference was the most precise, especially when used in conjunction with the formulae developed for ultrasonic measurements. Crown-rump length was found to be unsuitable to age fetuses beyond the first trimester due to distortion of the spine caused by compression in storage.     

Application of reinforcement learning for segmentation of transrectal ultrasound images

Background  

Among different medical image modalities, ultrasound imaging has a very widespread clinical use. But, due to some factors, such as poor image contrast, noise and missing or diffuse boundaries, the ultrasound images are inherently difficult to segment. An important application is estimation of the location and volume of the prostate in transrectal ultrasound (TRUS) images. For this purpose, manual segmentation is a tedious and time consuming procedure.     

基于Mask R-CNN的超声图像中胎儿头围测量方法

胎儿头围是产前超声检查中评价胎儿生长发育最重要的生物特征之一,但手工测量耗时费力且存在操作者的误差.对此,根据超声图像中胎儿头部接近椭圆形状的特征,提出头围测量损失函数.在Mask R-CNN的分割分支后,利用ElliFit算法对分割掩膜进行椭圆拟合,用Ramanujan公式计算拟合椭圆周长作为头围测量值,将头围真实值...     

Intrauterine diagnosis and pathology of fetal choroid plexus carcinoma – A case study

This is a case report of a 39-year-old pregnant woman whose fetus was found to have a large hydrocephalus on routine prenatal ultrasound at the 29th gestational week. A 56 mm × 73 mm mass was detected in the fetal brain arising from the brainstem and invading the third cerebral ventricle. On the subsequent fetal cranial MRI, T2-weighted image the tumor measured 55 mm × 50 mm × 48 mm and had a non-homogeneous consistency and irregular contours. Elective cesarean section was performed during gestational week 32, delivering a male fetus with a cranial circumference of 46 cm (normal circumference, 30 cm) and a birth weight of 2920 g. The infant expired 4 h following delivery. Autopsy revealed a carcinoma of the choroid plexus. Our case, like others, suggests that MRI is more accurate than prenatal ultrasound in prenatal brain tumor diagnosis. More precise morphological detail is provided by MRI, which improves surgical planning and survival.     

An informative probability model enhancing real time echobiometry to improve fetal weight estimation accuracy

A multinormal probability model is proposed to correct human errors in fetal echobiometry and improve the estimation of fetal weight (EFW). Model parameters were designed to depend on major pregnancy data and were estimated through feed-forward artificial neural networks (ANNs). Data from 4075 women in labour were used for training and testing ANNs. The model was implemented numerically to provide EFW together with probabilities of congruence among measured echobiometric parameters. It enabled ultrasound measurement errors to be real-time checked and corrected interactively. The software was useful for training medical staff and standardizing measurement procedures. It provided multiple statistical data on fetal morphometry and aid for clinical decisions. A clinical protocol for testing the system ability to detect measurement errors was conducted with 61 women in the last week of pregnancy. It led to decisive improvements in EFW accuracy.     

Fetal biometry in the Brachmann-de Lange syndrome

The Brachmann-de Lange syndrome (BDLS) is diagnosed in children on the basis of a distinctive clinical phenotype which includes retarded physical growth. Because there are no genetic or biochemical tests at present, the antenatal detection of the syndrome may depend upon identification of some aspect of the phenotype in the fetus using ultrasound imaging. We studied the growth of 23 subsequently diagnosed fetuses with the BDLS using standard biometric parameters defined by prenatal ultrasound imaging. Sonographic studies were obtained through a national parents' group, the Cornelia de Lange Syndrome Foundation. Assessment of fetal growth was made using four standardized measurements: the biparietal diameter, head circumference, femur length, and abdominal circumference. These values were compared to established tables of normal fetal growth and established rations of fetal body proportions. The cross-sectional growth curve derived using all measurements collected as a composite group indicates that growth retardation would be first detected as early as 25 weeks. In five fetuses with measurements both before and after 25 weeks of gestation, longitudinal growth curves indicated that the diagnosis of “small for gestational age” would have been suggested between 20 and 25 weeks. The mean fetal weight estimates closely followed the fifth centile curve of normal fetuses both before and after 25 weeks. Cephalic indices in BDLS fetuses indicated either frank brachycephaly (25%), or were at the upper portion of the normal range. Femur lengths were relatively short (less than 90% of their expected length ) in 4 of the 11 fetuses where such information could be obtained. BDLS fetuses demonstrate early and symmetric intrauterine growth retardation. We conclude that fetal biometry can provide a valuable index in the assessment of a pregnancy suspected to be at risk for a severely affected BDLS child. © 1993 Wiley-Liss, Inc.     

Fetal Ultrasound Image Segmentation for Automatic Head Circumference Biometry Using Deeply Supervised Attention-Gated V-Net

Automatic computerized segmentation of fetal head from ultrasound images and head circumference (HC) biometric measurement is still challenging, due to the inherent characteristics of fetal ultrasound images at different semesters of pregnancy. In this paper, we proposed a new deep learning method for automatic fetal ultrasound image segmentation and HC biometry: deeply supervised attention-gated (DAG) V-Net, which incorporated the attention mechanism and deep supervision strategy into V-Net models. In addition, multi-scale loss function was introduced for deep supervision. The training set of the HC18 Challenge was expanded with data augmentation to train the DAG V-Net deep learning models. The trained models were used to automatically segment fetal head from two-dimensional ultrasound images, followed by morphological processing, edge detection, and ellipse fitting. The fitted ellipses were then used for HC biometric measurement. The proposed DAG V-Net method was evaluated on the testing set of HC18 (n = 355), in terms of four performance indices: Dice similarity coefficient (DSC), Hausdorff distance (HD), HC difference (DF), and HC absolute difference (ADF). Experimental results showed that DAG V-Net had a DSC of 97.93%, a DF of 0.09 ± 2.45 mm, an AD of 1.77 ± 1.69 mm, and an HD of 1.29 ± 0.79 mm. The proposed DAG V-Net method ranks fifth among the participants in the HC18 Challenge. By incorporating the attention mechanism and deep supervision, the proposed method yielded better segmentation performance than conventional U-Net and V-Net methods. Compared with published state-of-the-art methods, the proposed DAG V-Net had better or comparable segmentation performance. The proposed DAG V-Net may be used as a new method for fetal ultrasound image segmentation and HC biometry. The code of DAG V-Net will be made available publicly on https://github.com/xiaojinmao-code/.     

Development of the fetal uterus between 19 and 38 weeks of gestation: in-utero ultrasonographic measurements.

In-utero assessment of the internal female genitalia is important for determination of fetal gender in fetuses with suspected genital tract anomalies. We therefore measured fetal uterine transverse width and circumference from 19 weeks of gestation until term, using transvaginal and transabdominal high-resolution ultrasound techniques in order to establish nomograms. A prospective, cross-sectional study on 180 normal singleton pregnancies was performed. Data were obtained for 140 normal fetuses. The mean +/- SD uterine width and circumference were 12.9 +/- 4.1 mm (95% confidence interval 12.1-13.7), and 40.2 +/- 12.5 mm (95% confidence interval 37.9-42.5) respectively. Uterine size as a function of gestational age was expressed by the regression equations: uterine width (mm) = 12.9 + 0.7 x gestational age (weeks), and uterine circumference (mm) = 40.2 + 2.1 x gestational age. The correlation coefficients, r = 0.885 and r = 0.888, for uterine width and circumference, by gestational age respectively, were highly statistically significant (P < 0.001). A nomogram of uterine width and circumference per gestational week, and the 95% prediction limits were defined. The present data offer baseline measurements of the fetal uterus that may allow intrauterine assessment of the female genital tract and associated fetal gender.     

基于人工神经网络的足月胎儿体重预测方法

对胎儿体重的预测在产科临床上具有非常重要的意义,传统上采用回归分析方法预测胎儿体重,存在可靠性差等缺点。本研究采用反向传播(BP)人工神经网络方法预测胎儿体重,实验中采用双顶径、小脑横径、腹围、肝脏长度、股骨长度、股骨皮下脂肪厚度、孕龄等参数作为BP神经网络的输入参数,网络由输入层、隐含层和输出层三部分组成。对109例临床资料进行预测,结果为:训练组预测符合率达89.77%,平均绝对误差104.22g,平均相对误差3.24%;验证组预测符合率达76.19%,平均绝对误差190.84g,平均相对误差5.60%。表明人工神经网络预测胎儿体重方法十分有效,准确性高于回归方程。     

Computer Vision Approach for Ultrasound Doppler Angle Estimation

Doppler ultrasound is an important noninvasive diagnostic tool for cardiovascular diseases. Modern ultrasound imaging systems utilize spectral Doppler techniques for quantitative evaluation of blood flow velocities, and these measurements play a crucial rule in the diagnosis and grading of arterial stenosis. One drawback of Doppler-based blood flow quantification is that the operator has to manually specify the angle between the Doppler ultrasound beam and the vessel orientation, which is called the Doppler angle, in order to calculate flow velocities. In this paper, we will describe a computer vision approach to automate the Doppler angle estimation. Our approach starts with the segmentation of blood vessels in ultrasound color Doppler images. The segmentation step is followed by an estimation technique for the Doppler angle based on a skeleton representation of the segmented vessel. We conducted preliminary clinical experiments to evaluate the agreement between the expert operator’s angle specification and the new automated method. Statistical regression analysis showed strong agreement between the manual and automated methods. We hypothesize that the automation of the Doppler angle will enhance the workflow of the ultrasound Doppler exam and achieve more standardized clinical outcome.     

超声不同数学公式评估中国胎儿体重的准确性分析

目的：针对中国人种,在不同孕周,比较12种超声估计胎儿体重的公式来预测新生儿体重的准确性。并同时比较经验丰富与新手之间评估准确性的差异。方法：回顾性分析对488例单胎中国人得胎儿体重用12种公式分别评估胎儿体重。胎儿生物学测量的径线在分娩前7天测量。结果：488例孕妇中,31例（6．4％）为小于胎龄儿（SGA）,36例（7．3％）为大于胎龄儿。对于所有的病例,Aoki和HadlockI有最好的组内相关效率。对于SGA而言,Combs的预测效率最高。对于体重在2501g至3999g之间的胎儿,Aoki的预测效率最高。对于LGA,Merz公式有最强的预测准确率。在经验丰富与新手预测胎儿体重的准确性方面,经过系统训练的熟练操作人员的准确性明显高于新手的评估准确率。结论：在决定分娩时机和分娩方式,尤其是在需要催产或期待妊娠时,临床上必须要考虑到胎儿体重的情况。在不同种族,不同体重范围时应该运用不同的超声胎儿体重的公式。超声工作者应该在上岗前系统的培训超声测量胎儿体重的标准平面及操作技巧以提高评估的准确性。     

Longitudinal reference ranges for fetal ultrasound biometry in twin pregnancies

OBJECTIVE:

The purpose of this study was to establish longitudinal reference ranges for fetal ultrasound biometry measurements and growth parameters in twin pregnancies.

METHOD:

A total of 200 uncomplicated twin pregnancies before 21 weeks of gestation were recruited for this prospective, longitudinal study. Women who abandoned follow-up, pregnancies with unknown outcomes or pregnancies with complications were excluded. Ultrasound scans were performed every three weeks, and biparietal and occipitofrontal diameters, head and abdominal circumferences, and femur diaphysis length measurements were obtained for each fetus at each visit. Estimated fetal weight, biparietal/occipitofrontal diameter, head circumference/abdominal circumference, and femur diaphysis length/abdominal circumference ratios were also calculated. Multilevel regression analysis was performed on normalized data.

RESULTS:

A total of 807 ultrasound examinations were performed in 125 twin pregnancies between 14 and 38 weeks of gestation (6.5±1.4 scans/pregnancy). Regression analysis demonstrated significant correlations for all variables with gestational age, namely log of the biparietal diameter (r = 0.98), log of the occipitofrontal diameter (r = 0.98), log of the head circumference (r = 0.99), log of the abdominal circumference (r = 0.98), square root of the femur length (r = 0.99), log of the estimated fetal weight (r = 0.99), biparietal/occipitofrontal ratio (r = -0.11), head/abdomen circumference ratio (r = -0.56), and log of the femur length/abdominal circumference ratio (r = 0.61). Values corresponding to the 10^th, 50^th, and 90^th percentiles for estimated fetal weight at 28, 32, and 36 weeks, respectively, were as follows: 937, 1,096, 1,284 g; 1,462, 1,720, 2,025 g; and 2,020, 2,399, 2,849 g.

CONCLUSION:

In twin pregnancies, fetal ultrasound biometry measurements and growth parameters show a significant correlation with gestational age.     

Snakes based segmentation of the common carotid artery intima media

Ultrasound measurements of the human carotid artery walls are conventionally obtained by manually tracing interfaces between tissue layers. In this study we present a snakes segmentation technique for detecting the intima-media layer of the far wall of the common carotid artery (CCA) in longitudinal ultrasound images, by applying snakes, after normalization, speckle reduction, and normalization and speckle reduction. The proposed technique utilizes an improved snake initialization method, and an improved validation of the segmentation method. We have tested and clinically validated the segmentation technique on 100 longitudinal ultrasound images of the carotid artery based on manual measurements by two vascular experts, and a set of different evaluation criteria based on statistical measures and univariate statistical analysis. The results showed that there was no significant difference between all the snakes segmentation measurements and the manual measurements. For the normalized despeckled images, better snakes segmentation results with an intra-observer error of 0.08, a coefficient of variation of 12.5%, best Bland–Altman plot with smaller differences between experts (0.01, 0.09 for Expert1 and Expert 2, respectively), and a Hausdorff distance of 5.2, were obtained. Therefore, the pre-processing of ultrasound images of the carotid artery with normalization and speckle reduction, followed by the snakes segmentation algorithm can be used successfully in the measurement of IMT complementing the manual measurements. The present results are an expansion of data published earlier as an extended abstract in IFMBE Proceedings (Loizou et al. IEEE Int X Mediterr Conf Medicon Med Biol Eng POS-03 499:1–4, 2004).     

基于改进图割的超声瞳孔图像分割与直径测量

传统的瞳孔直径测量是通过医生手工标定,对于眼外伤和丧失意识的患者测量不方便。针对瞳孔直径测量的人工交互量大且测量鲁棒性不强的问题,采用图割算法分割瞳孔超声图像并测量瞳孔直径。对传统图割算法进行两个方面的改进,采用自适应阈值的区域生长代替人为种子点选取,在保证分割效果的基础上减少了图割的交互量;在能量函数的数据项部分增加图像的梯度信息,减少了原始算法分割结果中出现的小区域,增强了对弱边缘的分割。最后,对采集到的超声瞳孔图像进行自动分割、自动测量瞳孔直径,可以得到患者瞳孔的直径动态变化,给临床诊断提供依据。为了验证算法的有效性,对10位患者的动态瞳孔超声图像进行基于改进图割的瞳孔直径测量,并与医生的手动测量结果对比。结果表明,本方法的结果与医生手动测量结果的绝对误差小于0.2 mm,相关系数不小于0.83。通过改进图割算法,改善了分割效果,实现了超声瞳孔动态图像的自动直径测量,并可有效代替瞳孔直径的人工测量,减少人工交互量。     

Fetal size at the 32nd gestational week is associated with the risk of breech presentation at term birth

Objectives

The association patterns between breech presentation at birth and fetal biometry at the first, second, and third trimesters, newborn size but also maternal age, body height, prepregnancy weight status as well as gestational weight gain, were analyzed using a dataset of 4501 singleton term birth in Vienna, Austria.

Methods

In this medical record-based study, fetal biometry was reconstructed based on the results of three ultrasound examinations conducted at the 11th/12th, 20th, and 32nd gestational weeks. Head dimensions, abdominal dimensions, and femur length were determined by sonography. Birth weight, birth length, and head circumference were measured immediately after birth.

Results

The total breech presentation rate at birth was 6.2%. Breech newborns were significantly (p < 0.001) shorter and lighter at the time of birth, their head circumferences, however, were significantly larger (p = 0.001). At the 32nd week, breech fetuses showed significantly smaller biparietal breadths, but highly significantly longer heads. Their abdominal dimensions were significantly smaller, and their femora were shorter. Higher maternal age, and a longer, but narrower fetal head as well as smaller abdominal dimensions at the 32nd gestational week were independently related to a higher risk of breech presentation at the time of birth.

Conclusions

Fetuses who remain in a breech presentation until term birth (≥37 gestational weeks) differed significantly in head and abdominal dimensions from cephalic fetuses from the 32nd gestational week onwards.     

Maternal fat mass at mid-pregnancy and birth weight in Brazilian women

Abstract

Background: The relationship between maternal body composition and foetal development is unclear.

Aim: To determine the relationship between maternal body composition [fat mass (FM) and fat-free mass (FFM)] and foetal growth and birth weight, independent of potential confounding factors.

Subjects and methods: This study consisted of 92 women, normal and overweight/obese, recruited from the Instituto Fernandes Figueira in Rio de Janeiro, Brazil. Body composition (FM and FFM) was estimated using bioelectrical impedance. Foetal growth was assessed using serial ultrasound measurements at the second and third trimester and infant's weight and length were measured at birth. Multiple linear regression analyses were used to determine the association between maternal FM and FFM and birth weight adjusted for gestational age (BWt) and change in estimated foetal weight (ΔEFW), controlling for infant gender, maternal serum glucose, energy intake, parity, height and income.

Results: Maternal FM, but not FFM, was positively associated with BWt (p?=?0.02) and borderline with ΔEFW (p?=?0.05). FM expressed as a percentage of body weight (%FM) showed a significant positive association with BWt (p?<?0.001) and ΔEFW (p?<?0.01). Using backward linear regression analysis, FM was a significant predictor of BWt (p?<?0.001) and ΔEFW (p?=?0.03), but not change in femur length.

Conclusion: In this small sample of normal and overweight/obese women, maternal FM at mid-pregnancy is associated with neonatal BW and foetal growth.     

Antepartum non-invasive evaluation of opening and closing timings of the cardiac valves in fetal cardiac cycle

In this study, we propose a non-invasive algorithm to recognize the timings of fetal cardiac events on the basis of analysis of fetal ECG (FECG) and Doppler ultrasound signals. Multiresolution wavelet analysis enabled the frequency contents of the Doppler signals to be linked to the opening (o) and closing (c) of the heart’s valves (Aortic (A) and Mitral (M)). M-mode, B-mode and pulsed Doppler ultrasound were used to verify the timings of opening and closure of these valves. In normal fetuses, the time intervals from Q-wave of QRS complex of FECG to opening and closing of aortic valve, i.e., Q-Ao and Q-Ac were found to be 79.3 ± 17.4 and 224.7 ± 13.3 ms, respectively. For the mitral valve, Q-Mc and Q-Mo were found to be 27.7 ± 9.4 and 294.6 ± 21.3 ms, respectively. Correlations among the timings in opening and closing of cardiac valves were found to be higher in abnormal fetuses than that in normal ones.     

Analysis of semi-automated method for femur length measurement from foetal ultrasound

The motivation of this paper is to analyse the efficiency and reliability of our proposed algorithm of femur length (FL) measurement for the estimation of gestational age. The automated methods are divided into the following components: threshold, segmentation and extraction. Each component is examined, and improvements are made with the objective of finding the optimal result for FL measurement. The methods are tested with a total of 200 different digitized ultrasound images from our database collection. Overall, the study shows that the watershed-based segmentation method combined with enhanced femur extraction algorithm and a 12 × 12 block averaging seed-point threshold method perform identically well with the expert measurements for every image tested and superior as compared to a previous method.     

Nomograms of the fetal thymus for clinical practice

IntroductionThe fetal thymus may be visualized using ultrasonography (USG) and is typically located in the mediastinum. In the past years, the size of the fetal thymus has served not only as a marker of genetic or heart defects but also as a predictive factor for intrauterine growth restriction, premature birth, preeclampsia, chorioamnionitis or even neonatal sepsis.Material and methodsA total of 410 fetuses were qualified for the study. Fetuses with heart defects were excluded from the study. The fetal thymus was evaluated with ultrasonography between the 14^th and 40^th week of gestation. After obtaining a standard transverse view encompassing the three great vessels, thymus measurements were attempted, i.e. maximal transverse diameter, circumference and surface area. Linear regression was used for statistical analysis, yielding 3 models, each with a different dependent variable. The confidence interval for each model was set at 80% to aid the comparison with centile grid growth charts for neonates and children. The test was regarded as statistically significant when p < 0.05.ResultsFrom a total of 410 fetuses the thymus transverse diameter, circumference and area were successfully measured in 410, 320 and 330 cases, respectively. The probabilities are lower than 0.0005 for each model, which means that each model is quite statistically significant.ConclusionsThe coverage of healthy thymus nomograms in the fetal population may be the basis for the identification of fetuses at risk of hypoplasia or thymic hyperplasia, which seems particularly important from the point of view of the detection of potential inborn immunological disorders