Ultrasound Estimation Research Articles

Amniotic Fluid Volume Assessment: Eight Lessons Learned.

Actual AFV can be determined by a dye-dilution technique or be directly measured at cesarean. This allows investigators to correlate estimated and actual AFVs. Lessons learned by assessing the relationship of estimated to actual AFVs. 1) Ultrasound estimates normal actual AFVs well, but abnormal AFVs poorly. 2) Quantile regression is a better statistical methodology to create a normal AFV curve across pregnancy. 3) There is no difference in the accuracy of the subjective (visualization without measurements) compared with the objective (visualization with measurements) technique in identifying normal and abnormal AFVs. 4) Color Doppler use leads to the over-diagnosis of oligohydramnios. 5) Intravenous hydration increases actual AFVs. 6) The estimation of AFV can be done with the transducer held perpendicular to the floor or perpendicular to the uterine contour. 7) The single deepest pocket should be used for identifying low AFVs. 8) The AFI should be used for identifying high AFVs.

Ultrasonographic Estimation of Total Brain Volume: 3D Reliability and 2D Estimation. Enabling Routine Estimation During NICU Admission in the Preterm Infant.

Objectives: The aim of this study is to explore if manually segmented total brain volume (TBV) from 3D ultrasonography (US) is comparable to TBV estimated by magnetic resonance imaging (MRI). We then wanted to test 2D based TBV estimation obtained through three linear axes which would enable monitoring brain growth in the preterm infant during admission.Methods: We included very low birth weight preterm infants admitted to our neonatal intensive care unit (NICU) with normal neuroimaging findings. We measured biparietal diameter, anteroposterior axis, vertical axis from US and MRI and TBV from both MRI and 3D US. We calculated intra- and interobserver agreement within and between techniques using the intraclass correlation coefficient and Bland-Altman methodology. We then developed a multilevel prediction model of TBV based on linear measurements from both US and MRI, compared them and explored how they changed with increasing age. The multilevel prediction model for TBV from linear measures was tested for internal and external validity and we developed a reference table for ease of prediction of TBV.Results: We used measurements obtained from 426 US and 93 MRI scans from 118 patients. We found good intra- and interobserver agreement for all the measurements. US measurements were reliable when compared to MRI, including TBV which achieved excellent agreement with that of MRI [ICC of 0.98 (95% CI 0.96–0.99)]. TBV estimated through 2D measurements of biparietal diameter, anteroposterior axis, and vertical axis was comparable among both techniques. We estimated the population 95% confidence interval for the mean values of biparietal diameter, anteroposterior axis, vertical axis, and total brain volume by post-menstrual age. A TBV prediction table based on the three axes is proposed to enable easy implementation of TBV estimation in routine 2D US during admission in the NICU.Conclusions: US measurements of biparietal diameter, vertical axis, and anteroposterior axis are reliable. TBV segmented through 3D US is comparable to MRI estimated TBV. 2D US accurate estimation of TBV is possible through biparietal diameter, vertical, and anteroposterior axes.

Network Meta-Analysis: Noninvasive Imaging Modalities for Identifying Clinically Significant Portal Hypertension.

Although measurement of the hepatic venous pressure gradient (HVPG) is the current reference standard for obtaining portal venous pressures, several noninvasive imaging-based modalities have been proposed as alternatives. We performed a systematic review and meta-analysis to compare the diagnostic accuracy of noninvasive imaging approaches for identifying clinically significant portal hypertension (CSPH). Two independent reviewers conducted a literature search of PubMed, SCOPUS, and the Cochrane Library from inception until January 5, 2021. The following imaging modalities were compared to HVPG: computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance elastography, ultrasound, transient elastography (TE), shear wave elastography (SWE), acoustic radiation force impulse (ARFI) imaging, contrast-enhanced ultrasound (CEUS), and subharmonic-aided pressure estimation (SHAPE). Sensitivity, specificity, diagnostic odds ratio (DOR), and area under the curve (AUC) for summary receiver operating characteristic were calculated using both frequentist random effects and Bayesian network meta-analytic approaches. We analyzed 45 studies of 5678 patients. A broad overlapping confidence interval (CI) of DOR was observed among different imaging modalities: ARFI (30.5; 95% CI 12.7-73.3), CEUS and SHAPE (21.1; 95% CI 6.4-69.8), TE of liver stiffness (21.1; 95% CI 13.3-33.5), CT and MRI (13.7; 95% CI 7.40-25.4), SWE of liver stiffness (10.5; 95% CI 5.2-21.1), and ultrasound (9.5; 95% CI 4.9-18.4). The AUC of all imaging methods exceeded 0.8, indicating very good performance. At a cutoff of 80% specificity, TE, CEUS, and SHAPE exceeded 80% sensitivity. Overall, noninvasive imaging modalities perform well for identifying CSPH. Clinicians should consider these noninvasive and cost-efficient tests when diagnosing CSPH.

Use of Handheld Ultrasound to Estimate Right Atrial Pressure in a Pulmonary Hypertension Clinic

Rationale: Point-of-care ultrasonography is an invaluable asset for inpatient decision-making. Whether handheld ultrasound can be used in the outpatient management of pulmonary hypertension is unknown. Objectives: We investigated whether a handheld ultrasound estimate of right atrial pressure correlates with B-type natriuretic peptide (BNP) and clinical outcome over time in outpatients with pulmonary hypertension. Methods: This prospective study included outpatients in a Pulmonary Hypertension Comprehensive Care Center clinic who had a same-day BNP concentration. We used a handheld ultrasound to measure inferior vena cava size and collapsibility, which were used to estimate right atrial pressure (eRAP) and categorize it as normal, intermediate, or high. Correlation analysis was used to compare these ultrasound measurements with BNP at baseline and over time. Cox regression was used to determine whether these measurements were associated with time to clinical worsening. Results: Ninety patients (60% Group 1 pulmonary hypertension) were enrolled. Patients with an intermediate or high eRAP category at baseline had higher BNP concentrations than patients with normal eRAP. For every transition in eRAP category (e.g., from normal to intermediate) between clinic visits, BNP changed by an average of 155 pg/ml (95% confidence interval [CI], 84-227). Higher baseline eRAP category was independently associated with more than twofold increased risk for clinical worsening (hazard ratio, 2.44; 95% CI, 1.47-4.07). Conclusions: Right atrial pressure estimated by portable handheld ultrasound correlates with BNP at baseline and serially over time. Furthermore, eRAP is independently associated with clinical worsening. The use of portable handheld ultrasound to estimate right atrial pressure should be considered in pulmonary hypertension clinics. Clinical trial registered at clinicaltrials.gov (NCT02873039).

POSITION OF IN-THE-BAG POSTERIOR CHAMBER INTRAOCULAR LENSES RELATIVE TO THE LIMBUS: Applications to Scleral-Sutured Lenses.

To characterize the true position of in-the-bag intraocular lenses (IOLs) relative to the limbus using ultrasound biomicroscopy and estimate scleral-sutured IOL positioning. This prospective single-center study included 70 eyes of 41 patients with in-the-bag posterior chamber IOLs. Four vertical ultrasound biomicroscopy captures were performed in each eye in the superior, inferior, nasal, and temporal quadrants. Postoperative biometric data were collected. The primary outcome was the vertical distance of the in-the-bag IOL from the sclerocorneal limbus. Secondary outcomes included anterior shift and refractive change of a theoretical scleral-sutured IOL using sclerotomies at 2.5 mm and 3 mm posterior to the limbus. A total of 265 ultrasound biomicroscopy images were analyzed, including 64 superior, 69 inferior, 66 nasal, and 66 temporal. The true in-the-bag IOL position measured as distance posterior to the sclerocorneal limbus was 4.23 ± 0.56 mm superiorly, 4.22 ± 0.46 mm inferiorly, 3.95 ± 0.48 mm nasally, and 3.86 ± 0.52 mm temporally. The anterior shift of a theoretical scleral-sutured IOL was 0.60 mm for a 3-mm sclerotomy and 0.93 mm for a 2.5-mm sclerotomy, resulting in a theoretical myopic shift of 0.45 diopter (D) and 0.79 D, respectively, assuming a 15-D IOL. Larger biometric measurements correlated with a more posterior in-the-bag position. True in-the-bag IOL position was found to be more posterior than estimates of scleral-sutured IOLs. Additional corrections in scleral-sutured IOL calculations may improve refractive outcomes.

Fast linear least-squares method for ultrasound attenuation and backscatter estimation

The ultrasonic attenuation and backscatter coefficients of tissues are relevant acoustic parameters due to their wide range of clinical applications. In this paper, a linear least-squares method for the estimation of these coefficients in a homogeneous region of interest based on pulse-echo measurements is proposed. The method efficiently fits an ultrasound backscattered signal model to the measurements in both the frequency and depth dimension simultaneously at a low computational cost. It is demonstrated that the inclusion of depth information has a positive effect particularly on the accuracy of the estimated attenuation. The sensitivity of the attenuation and backscatter coefficients’ estimates to several predefined parameters such as the window length, window overlap and usable bandwidth of the spectrum is also studied. Comparison of the proposed method with a benchmark approach based on dynamic programming highlights better performance of our method in estimating these coefficients, both in terms of accuracy and computation time. Further analysis of the computation time as a function of the predefined parameters indicates our method’s potential to be used in real-time clinical settings.

Ultrasound Measurements of Subcutaneous Fat Thickness Are Robust Against Hydration Changes.

Ultrasound is an appealing tool to assess body composition, combining the portability of a field method with the accuracy of a laboratory method. However, unlike other body composition methods, the effect of hydration status on validity is unknown. This study evaluated the impact of acute hydration changes on ultrasound measurements of subcutaneous fat thickness and estimates of body fat percentage. In a crossover design, 11 adults (27.1 ± 10.5years) completed dehydration and hyperhydration trials to alter body mass by approximately ±2%. Dehydration was achieved via humid heat (40 °C, 60% relative humidity) with exercise, whereas hyperhydration was via ingestion of lightly salted water. Ultrasound measurements were taken at 11 body sites before and after each treatment. Participants lost 1.56 ± 0.58kg (-2.0 ± 0.6%) during the dehydration trial and gained 0.90 ± 0.21kg (1.2 ± 0.2%) during the hyperhydration trial even after urination. The sum of fat thicknesses as measured by ultrasound differed by <0.90mm across trials (p = .588), and ultrasound estimates of body fat percentage differed by <0.5% body fat. Ultrasound measures of subcutaneous adipose tissue were unaffected by acute changes in hydration status by extents beyond which are rare and overtly self-correcting, suggesting that this method provides reliable and robust body composition results even when subjects are not euhydrated.

Noise Suppression for Ultrasound Attenuation Coefficient Estimation Based on Spectrum Normalization.

Ultrasound attenuation coefficient estimation (ACE) has great diagnostic potential for fatty liver detection and assessment. In a previous study, we proposed a reference phantom-free ACE method, called reference frequency method (RFM), which does not require a calibrated phantom for normalization. The power of each frequency component can be normalized by the power of an adjacent frequency component in the spectrum to cancel system-dependent effects such as focusing and time gain compensation (TGC). RFM demonstrated accurate ACE in both phantom and in in-vivo liver studies. However, our study also showed that the robustness and penetration of RFM were affected by noise in the ACE signals. Here we propose a noise suppression (NS) and a signal-to-noise ratio (SNR) quality control method to reduce the influence of noise on ACE-RFM performance. The proposed methods were tested in harmonic ACE because harmonic imaging is a more frequently used mode than fundamental imaging for abdominal applications. After applying the NS and SNR control methods, the noise-induced bias for attenuation estimation in harmonic ACE was effectively reduced, leading to significantly improved effective penetration depth. The proposed methods directly measure the noise spectrum of the ultrasound system, which can also be adapted to other spectrum-based ACE methods, such as the reference phantom method and the spectra shift method.

Diagnostic accuracy of modified Hadlock formula for fetal macrosomia in women with gestational diabetes and pregnancy weight gain above recommended.

Women with gestational diabetes (GDM) and weight gain during pregnancy above recommended more often give birth to macrosomic children. The goal of this study was to evaluate the diagnostic accuracy of the modified formula for ultrasound assessment of fetal weight created in a pilot study using a similar specimen in comparison to the Hadlock-2 formula. This is a prospective, cohort, applicative, observational, quantitative, and analytical study, which included 213 pregnant women with a singleton pregnancy, GDM, and pregnancy weight gain above recommended. Participants were consecutively followed in the time period between July 1st, 2016, and August 31st, 2020. Ultrasound estimations were made within three days before the delivery. Fetal weights estimated using both formulas were compared to the newborns' weights. A total of 133 fetal weight estimations were made. In comparison to the newborns' weight modified formula had significantly smaller deviation in weight estimation compared to the Hadlock-2 formula, higher frequency of deviation within 5% of newborns weights (78.2% [95% CI=0.74-0.83] vs. 60.2%), smaller frequency of deviations from 5 to 10% (19.5 vs. 33.8%) and above 10%, which was even more significant among macrosomic children. There were 36/50 (72%) correctly diagnosed cases of macrosomia by modified and 33/50 (66%) by Hadlock-2 formula. Area under the curve (AUC) for the modified formula was 0.854 (95% CI=0.776-0.932), and for the Hadlock-2 formula 0.824 (95% CI=0.740-0.908). The positive predictive value of the modified formula was 81.81%, the negative 97.91%. In cases of greater fetal weights, the modified formula showed greater precision.

Factors Affecting Ultrasonographic Fetal Weight Estimation Accuracy in Low Birth Weight Newborns

Objective: To investigate the accuracy of fetal weight estimation made by the last prenatal ultrasound measurement in low birth weight newborns (&lt;2500 g). Study Design: A total of 1082 women were evaluated in this retrospective cohort study. Demographic and clinical information of the mother and newborn and obstetric ultrasonography measurements and findings performed in the last week before birth were recorded. Accuracy of fetal weight estimation and parameters affecting it was investigated. Results: Accurate estimation rates were lower in the term compared to the preterm delivery group; and in the SGA group compared to the AGA group (respectively, p=0.016, p=0.032). Accurate estimation rates (p=0.182) were comparable between the 500-1500 g and 1501-2500 g subgroups. The multiple linear regression analysis showed that gestational age at birth, birth weight, examination during labor, and duration between examination to delivery were statistically significant for the accurate estimation(p=0.001) Conclusions: Accurate estimation rates were lower in the term compared to the preterm delivery group, and in the SGA group compared to the AGA group. The factors affecting accurate estimation were found to be gestational age at birth, birth weight, examination during labor, and duration between examination to delivery.Keywords: Accurate estimation rate, Duration between examination to delivery, Examination during

COMPARATIVE STUDY OF DIFFERENT FORMULAE OF ULTRASONOGRAPHIC QUANTIFICATION OF THE AMOUNT OF PLEURAL EFFUSION

Background: Pleural effusion may be a result of a primary pulmonary illness. It also can be the pleural manifestation of numerous of diseases that primarily affect other organs. Quantification of pleural effusion is of great value in clinical practice, as it usually guides the plan of management. Chest ultrasound (U/S) is one of the helpful non-invasive means in estimating pleural fluid volume. Objective: To correlate the U/S estimated volumes of pleural fluid calculated by studied formulae, with the actual effusion volume, and to identify the most accurate formula in quantifying the pleural fluid volume. Patients and Methods: This prospective cross-sectional study was carried out in the department of Chest, Bab Al-sha'reia University Hospital, during the period from October 2019 to September 2020, and included forty patients with clinical and radiological diagnosis of pleural effusion. Ultrasound estimation of the amount of pleural effusion was done using 4 different formulae, followed by full pleural drainage through either simple aspiration or tube thoracostomy. Lastly, the ultrasonographically estimated fluid volumes were then compared to the actually drained fluid volume. Results: The supine formulae showed excellent correlation with the drained pleural fluid volume, with Pearson correlation coefficient(r) = 0.9607 and 0.9602 for Eibenberger and Balik formulae respectively (p-value <0.0001). On the other side, the erect formulae were found to have reasonable correlations with the drained volume, with r= 0.4017 (p-value= 0.0102) and 0.5729 (p-value <0.0001) for Goecke1 and Goecke 2 respectively. All studied formulae failed to quantify the pleural effusion volume accurately when comparing its estimated volume to the actually drained fluid volume. Conclusion: The 4 studied formulae had good correlations with the actually drained volume. However, supine formulae were better than erect formulae.

Deep Convolutional Neural Networks for Displacement Estimation in ARFI Imaging.

Ultrasound elasticity imaging in soft tissue with acoustic radiation force requires the estimation of displacements, typically on the order of several microns, from serially acquired raw data A-lines. In this work, we implement a fully convolutional neural network (CNN) for ultrasound displacement estimation. We present a novel method for generating ultrasound training data, in which synthetic 3-D displacement volumes with a combination of randomly seeded ellipsoids are created and used to displace scatterers, from which simulated ultrasonic imaging is performed using Field II. Network performance was tested on these virtual displacement volumes, as well as an experimental ARFI phantom data set and a human in vivo prostate ARFI data set. In the simulated data, the proposed neural network performed comparably to Loupas's algorithm, a conventional phase-based displacement estimation algorithm; the rms error was [Formula: see text] for the CNN and 0.73 [Formula: see text] for Loupas. Similarly, in the phantom data, the contrast-to-noise ratio (CNR) of a stiff inclusion was 2.27 for the CNN-estimated image and 2.21 for the Loupas-estimated image. Applying the trained network to in vivo data enabled the visualization of prostate cancer and prostate anatomy. The proposed training method provided 26 000 training cases, which allowed robust network training. The CNN had a computation time that was comparable to Loupas's algorithm; further refinements to the network architecture may provide an improvement in the computation time. We conclude that deep neural network-based displacement estimation from ultrasonic data is feasible, providing comparable performance with respect to both accuracy and speed compared to current standard time-delay estimation approaches.

Ultrasonographic measurement of the transcerebellar diameter for gestational age estimation in the third trimester.

Ultrasonographic estimation of gestational age is done routinely by using fetal biometric parameters, such as the biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and head circumference (HC). Gestational dating by ultrasound is reliable in the 1st trimester, but discrepancies increase to more than 3weeks in the 3rd trimester. To study the accuracy of gestational age estimation by the transcerebellar diameter (TCD) in the 3rd trimester of singleton pregnancies whose gestational age is known. A prospective study was carried out in the Department of Obstetrics and Gynecology at NDMC Medical College and Hindu Rao Hospital, Delhi, India, from October 2017 to May 2019 after obtaining clearance from the ethical committee. The study included 100 women aged 18-35years with singleton pregnancies in the 3rd trimester with a gestational age ≥ 28weeks; the women provided informed consent and filled in an F-form to rule out any sex determination of the baby. Only those women who had regular menstrual cycles 6months before conception, who were sure of their last menstrual period (LMP), who had a gestational dating scan done up to 14weeks, and for whom congenital malformation of the fetus had been ruled out by mid-trimester ultrasound were included. Gestational age was obtained for the measured BPD, HC, AC, FL, and TCD. A paired t-test was used for the comparison between the period of gestation (POG) by the 1st ultrasonography (USG) and that by the AC, BPD, FL, HC, and TCD. The estimation of gestational age by the BPD becomes gradually less reliable after 32weeks of pregnancy, that by the HC and FL after 36weeks, and that by the AC after 28weeks. Regression analysis was used to find a correlation of the various parameters, such as the POG by the 1st USG, BPD, HC, AC, FL, and TCD, with the POG by LMP. The correlation coefficient (r), coefficient of determination (R2), and p values were calculated. Of all the sonographic parameters for the estimation of gestational age, the TCD showed the highest correlation (r = 0.979; p < 0.0001) and the AC the lowest correlation. The mean difference between the estimate of gestational age by the TCD and that by the 1st trimester USG increased from ± 1day at weeks 28-32 to ± 1-2days at weeks 32-36 and further increased to ± 6days after 36weeks of pregnancy, which was statistically significant. This indicated that the TCD could estimate gestational age within 6days of near-term pregnancy. Thus, the TCD was a reliable parameter for the estimation of gestational age within 6days of near-term pregnancy along with routine biometry and an alternative parameter for the evaluation of gestational age when the LMP is not known.

English

BACKGROUND Early pregnancy failure is stated as noncompatible, intrauterine pregnancy with either an empty gestational sac or a gestational sac that contains an embryo or fetus which does not have any fetal cardiac activity in the initial 12 weeks of the pregnancy. In the assessment of early pregnancy, ultrasound plays a significant role. METHODS A prospective observational study was conducted in a tertiary care hospital between May 2019 and April 2020 among 500 pregnant females fulfilling the inclusion and exclusion criteria. Patient follow up was done by weekly telephonic calls until completing 12 weeks gestation or reporting miscarriage. Also, all patients were followed by the recommended routine ultrasound (US) scanning with or without emergency visits. RESULTS In our study period, 500 women fulfilling the inclusion criteria were included in our study. Out of whom, 85 (17.5 %) women had an early pregnancy failure (before 12 weeks). There was significantly lower mean gestational sac diameter (GSD), crown to rump length (CRL), fetal heart rate (FHR), and P-value &lt; 0.001 in women who experienced early pregnancy failure. In pregnancies where the GSD, CRL, and FHR were below the 5th percentile, early pregnancy failure was a more prone outcome. All pregnancies with FHR below 75 beats per minute ended in failure in the present study. When FHR was less than 128 beats per minute, there was enormous rise in the frequency of pregnancy failure. By comparison, yolk sac diameter (YSD) was a less significant predictor of early pregnancy failure. CONCLUSIONS First-trimester ultrasonographic estimations help in predicting early abortion. Risk appraisal tables dependent on combinations of abnormal parameters could significantly help in identifying abnormal pregnancy from normal pregnancy and could improve prediction rates. KEYWORDS Early Pregnancy Failure, Prediction, Transvaginal Ultrasonography, Ultrasonography

Ultrasound-guided fetometry in Egyptian sheep and she-goats

The aim of the present study was to buildup equation (s) for an intra-uterine fetal aging in Egyptian local sheep and she-goats breed using ultrasound. This study was carried out on a total number of 110 Baladi sheep and 74 she-goats under the field condition of Qalyubia governorate, Egypt. Ultrasound examination was conducted through trans-rectal and/or trans-abdominal routes. Throughout the gestation cycle between Day 26 and 112, Crown rump length (CRL) and biparietal diameter (BPD) were measured at least three times per test for each animal for accurate judgment. The correlation coefficient (R2) of BPD was higher than CRL in sheep and she-goats (0.9601 and 0.9598 vs. 0.898 and 0.903, respectively) at 39 to 112 days. Statistical analysis showed that no differences (P=0.258) between the BPD slopes represent ovine and caprine fetal growth rate. In conclusion, the use of ultrasound estimation in fetal biometry is useful to estimate the gestational age in sheep and she-goats with particular focus on BPD at all stages of pregnancy after breeding beyond Day 39.

Observer Influence with Other Variables on the Accuracy of Ultrasound Estimation of Fetal Weight at Term.

Background and Objectives: The accuracy with which the estimation of fetal weight (EFW) at term is determined is useful in order to address obstetric complications, since it is a parameter that represents an important prognostic factor for perinatal and maternal morbidity and mortality. The aim of this study was to determine the role of the experienced observers with other variables that could influence the accuracy of the ultrasound used to calculate EFW at term, carried out within a period of seven days prior to delivery, in order to assess interobserver variability. Materials and Methods: A cross-sectional study was performed including 1144 pregnancies at term. The validity of the ultrasound used to calculate EFW at term was analyzed using simple error, absolute error, percentage error and absolute percentage error, as well as the percentage of predictions with an error less than 10 and 15% in relation to maternal, obstetric and ultrasound variables. Results: Valid predictions with an error less than 10 and 15% were 74.7 and 89.7% respectively, with such precision decreasing according to the observer as well as in extreme fetal weights. The remaining variables were not significant in ultrasound EFW at term. The simple error, absolute error, percentage error and absolute percentage error were greater in cases of extreme fetal weights, with a tendency to overestimate the low weights and underestimate the high weights. Conclusions: The accuracy of EFW with ultrasound carried out within seven days prior to birth is not affected by maternal or obstetric variables, or by the time interval between the ultrasound and delivery. However, accuracy was reduced by the observers and in extreme fetal weights.

Preterm disparities between foreign and Swedish born mothers depend on the method used to estimate gestational age. A Swedish population-based register study.

This study aims to examine whether disparities in gestational age outcomes between foreign and Swedish-born mothers are contingent on the measure used to estimate gestational age and, if so, to identify which maternal factors are associated with the discrepancy. Using population register data, we studied all singleton live births in Sweden from 1992-2012 (n = 1,317,265). Multinomial logistic regression was performed to compare gestational age outcomes classified into very (<32 weeks) and late preterm (32-36 weeks), term and post-term derived from the last menstrual period (LMP) and ultrasound estimates in foreign- and Swedish-born women. Compared to Swedish-born women, foreign-born women had similar odds of very preterm birth (OR: 0.98 [95% CI: 0.98, 1.01]) and lower odds of moderately preterm birth (OR: 0.95 [95% CI: 0.92, 0.98]) based on ultrasound, while higher risks based on LMP (respectively, OR: 1.10 [95% CI: 1.07, 1.14] and 1.09 [95% CI: 1.06, 1.13]). Conclusions on disparities in gestational age-related outcomes by mother's country of origin depend on the method used to estimate gestational age. Except for very preterm, foreign-born women had a health advantage when gestational age is based on ultrasound, but a health disadvantage when based on LMP. Studies assessing disparities in very preterm birth by migration status are not affected by the estimation method but caution should be taken when interpreting disparities in moderately preterm and preterm birth rates.

Assessment of an ultrasound bladder scanner in prostate radiotherapy: A validation study and analysis of bladder filling variability.

During prostate radiotherapy treatment, it is important to ensure the position of the bladder and prostate is consistent between treatments. The aim of this study was to provide a quantitative basis for incorporating ultrasound bladder volume estimates into local practice for prostate radiotherapy. Agreement between bladder volume estimates obtained using computed tomography (CT) and ultrasound was assessed. Analysis of bladder volumes between planning and treatment scans was used to quantify expected variations in bladder volume over the course of radiotherapy. Dose-volume statistics were estimated and compared to planned dose constraints to propose a target bladder volume and tolerance. Bladder volume measurements were obtained from 19 radiotherapy patients using ultrasound and CT. Ultrasound underestimated bladder volume compared to CT with a mean bias of -28 ± 30 ml. Pre-treatment (planning) bladder volumes varied from 71 to 383 ml with a mean of 200 ml. Treatment bladder volumes reduced by more than half in 9% of patients during the course of their treatment, potentially leading to a 30% increase in mean bladder dose. Patients with pre-treatment bladder volumes < 200 ml were most likely to exhibit differences in bladder volume, resulting in 'out of tolerance' increases in dose. A pragmatic individualised drinking protocol, aimed at achieving a minimum ultrasound bladder volume of 200 ml at planning CT, may be beneficial to reproducibility in radiotherapy treatment. Ultrasound measurements prior to treatment should ideally confirm that bladder volume is at least half the volume measured at planning.

751 Longitudinal ultrasound versus gestation-adjusted projection of birth weight in pregnancies complicated by diabetes

The aim of this study was to compare two methods of estimating fetal weight at delivery in women with diabetes in pregnancy; the longitudinal method and the gestation-adjusted prediction (GAP) of birthweight. We conducted a retrospective cohort study of all pregnancies complicated by either pregestational (PDM) or gestational diabetes (GDM) from 2010-2019 with delivery weight and serial third trimester sonographic data available for analysis. Ultrasound estimates were documented at two time points between 28 0/7-31 6/7 and 32 0/7-35 6/7 weeks’ gestation. Fetal weight at birth was predicted using the longitudinal and GAP methods (Figure 1). A Pearson correlation coefficient for each projection measure was calculated compared to birthweight. Test statistics were calculated for prediction of birth weight >4500g. Factors associated with under- and overestimation (±500g) of birthweight were investigated. 1,057 patients were included in the study. Relatively high correlation was seen for both methods (longitudinal: r=.818; p<.001, GAP: r=.812; p<.001). Both the absolute difference (p<.830) and absolute percent error (p=.758) were not different between methods (Table 1). Underestimation using the GAP method was more likely in PDM (61.8% vs 43.9%; p<.001), higher fetal abdominal circumference percentile (AC, 91% vs 77%; P<.001), and EFW percentile (71% vs 59%; p<.005). Neither AC nor EFW was significant with underestimation of longitudinal projection. For both measures’ overestimation was associated with higher EFW, higher AC, and greater gestational age at delivery. The longitudinal method had a higher sensitivity for birthweight >4500g (43.9% [28.5-60.3%] vs 31.7% [18.1-48.1%]). While the longitudinal and GAP methods have similar overall levels of agreement with birthweight. The longitudinal method may perform better in women with pregestational diabetes and in fetuses at higher extremes of weight with better prediction of birthweight >4500g.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Application Of A Real-time Linear Array Ultrasound System To The Evaluation Of Live Cattle

A real time linear array ultrasound machine was assessed for bias accuracy and precision. A total of 51 heifers, and steers were scanned for fat thickness over the longissimus muscle, the shoulder and rump; for M. longissimus area between the 12th and 13th ribs; and marbling was subjectively evaluated from M. longissimus scans. Ultrasound data were compared with a live judging committee estimates and with carcass values obtained during USDA grading. Data adjusted for live weight were analysed by correlation and regression techniques. Ultrasound estimates of fat thickness were lower (P&lt;.01) than carcass measurements. Shoulder fat thickness estimation was the lowest in precision and accuracy. The residual standard deviations of ultrasound estimates of fat thickness were not (P&gt;.05) influenced by fat thickness and sex. Ultrasound estimates of M. longissimus area were not different (P&gt;.05) from carcass values and were high in precision (RSD: 2.6 to 6.5cm2). The precision and accuracy of data collected by real time linear array ultrasound system indicate a potential for the application of the ultrasound technique to grading of livestock and carcasses.