Z-score reference ranges for pulsed-wave Doppler indices of the cardiac outflow tracts in normal fetuses

Analysis of automatic fetal intracranial volume (ICV) measurement based on the optimized ultrasound Smart ICV method at 16-34 weeks of gestation

BACKGROUND

Fetal intracranial volume (ICV) can help evaluate the development of the prenatal central nervous system (CNS) from the three-dimensional (3D) attributes of the cranial structure. Accurate and rapid segmentation and calculation of the ICV are clinically significant. Virtual organ computer-aided analysis (VOCAL) is a commonly used method for measuring fetal ICV. However, its operation is highly complex and time-consuming. This study aimed to optimize the fetal Smart ICV method at 16-19 gestational weeks, verify the consistency of automatic and manual measurement of ICV, and assess an automatic and efficient method for evaluating fetal ICV growth in the second and third trimester of pregnancy.

METHODS

The ultrasound data of 950 healthy fetuses at 16-34 weeks of gestation were collected. First, the Smart ICV algorithm was optimized at 16-19 weeks. Second, the optimized Smart ICV was compared with the manual VOCAL method. Finally, growth curve and Z-score estimations for fetuses were established for growth assessment via optimized Smart ICV.

RESULTS

Compared with the nonoptimized version, the optimized Smart ICV yielded a lower Hausdorff distance (1.15±0.25 vs. 1.31±0.93 mm, P<0.05). Both intra- and inter-observer agreements were at a high level for ICV measurement based optimized Smart ICV [intra-observer intraclass correlation coefficient (ICC) =0.998, 95% confidence interval (CI): 0.996-0.999; inter-observer ICC =0.991, 95% CI: 0.988-0.996] and the 18 plane-VOCAL (intra-observer ICC =0.997, 95% CI: 0.995-0.998; inter-observer ICC =0.981, 95% CI: 0.979-0.991). Additionally, Bland-Altman analysis showed that the ICV data for the above two models had good agreement. Nevertheless, compared with the 18 plane-VOCAL, the optimized Smart ICV consumed less time (3.7±0.7 vs. 153.1±29.5 s, P<0.05). The best fitting model of gestational week for the Smart ICV was a cubic function, expressed as follows: y = -44.2445 + 0.1427x 2 + 0.0052x 3, where y is ICV and x is the gestational week. In addition, fetal ICV showed an accelerated growth trend in the second trimester.

CONCLUSIONS

The optimized Smart ICV showed excellent accuracy and efficiency in ICV measurements at 16-34 gestational weeks. Our results may help to establish a best-fit growth curve for ICV. Our findings suggest that the optimized Smart ICV method has the potential to be a reliable tool for fetal growth assessment during the second and third trimesters.

Reference Values for Fetal Cardiac Dimensions, Volumes, Ventricular Function and Left Ventricular Longitudinal Strain Using Doppler Ultrasound Gated Cardiac Magnetic Resonance Imaging in Healthy Third Trimester Fetuses

BACKGROUND

Recent advances in hardware and software permit the use of cardiac MRI of late gestation fetuses, however there is a paucity of MRI-based reference values.

PURPOSE

To provide initial data on fetal cardiac MRI-derived cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain in healthy developing fetuses >30 weeks gestational age.

STUDY TYPE

Prospective.

POPULATION

Twenty-five third trimester (34 ± 1 weeks, range of 32-37 weeks gestation) women with healthy developing fetuses.

FIELD STRENGTH/SEQUENCE

Studies were performed at 1.5 T and 3 T. Cardiac synchronization was achieved with a Doppler ultrasound device. The protocol included T2 single shot turbo spin echo stacks for fetal weight and ultrasound probe positioning, and multiplanar multi-slice cine balanced steady state free precession gradient echo sequences.

ASSESSMENT

Primary analyses were performed by a single observer. Weight indexed right ventricular (RV) and left ventricular (LV) volumes and function were calculated from short axis (SAX) stacks. Cardiac dimensions were calculated from the four-chamber and SAX stacks. Single plane LV longitudinal strain was calculated from the four-chamber stack. Interobserver variability was assessed in 10 participants. Cardiac MRI values were compared against available published normative fetal echocardiogram data using z-scores.

STATISTICAL TESTS

Mean and SDs were calculated for baseline maternal/fetal demographics, cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain. Bland-Altman and intraclass correlation coefficient analysis was performed to test interobserver variability.

RESULTS

The mean gestational age was 34 ± 1.4 weeks. The mean RV and LV end diastolic volumes were 3.1 ± 0.6 mL/kg and 2.4 ± 0.5 mL/kg respectively. The mean RV cardiac output was 198 ± 49 mL/min/kg while the mean LV cardiac output was 173 ± 43 mL/min/kg.

DATA CONCLUSION

This paper reports initial reference values obtained by cardiac MRI in healthy developing third trimester fetuses. MRI generally resulted in slightly larger indexed values (by z-score) compared to reports in literature using fetal echocardiography.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Assessment of fetal cardiac function in early fetal life: feasibility, reproducibility, and early fetal nomograms

BACKGROUND

Fetal cardiology has shown a rapid development in the past decades. Fetal echocardiography is not only used for the detection of structural anomalies but also to assess fetal cardiac function. Assessment of the fetal cardiac function is performed mostly in the second and third trimesters. The study of fetal cardiac function at the end of first trimester has not been investigated properly, and there is a lack of reference values at early gestational weeks.

OBJECTIVE

This study aimed to assess if the measurement of time-related parameters of cardiac function in the left ventricle of the fetal heart is feasible and reproducible at the end of the first trimester. If possible, we provide nomograms of these parameters from 11 to 13+6 gestational weeks.

STUDY DESIGN

We conducted a prospective observational study from March to September 2022. The study was carried out in 2 hospitals (Hospital Universitari Dexeus, Barcelona, and Hospital VITAHS 9 Octubre, Valencia, Spain). The scans were performed by 3 specialists in fetal medicine. The exclusion criteria were fetal cardiac rhythm abnormalities, abnormal nuchal translucency, abnormal ductus venosus, fetal malformations, stillbirth, estimated fetal weight <10 percentile, diabetes, and gestational hypertensive disorders. The cardiac function parameters studied in the left ventricle were isovolumetric contraction time, isovolumetric relaxation time, ejection time, filling time, cycle time, myocardial performance index, ejection time fraction, and filling time fraction. We study the feasibility and intra- and interobserver reproducibility of these parameters using the interclass correlation coefficient. Nomograms were created and the percentiles of the values of the different parameters were calculated.

RESULTS

A total of 409 cases were recruited but only 296 could be included in the statistical analysis once the exclusion criteria were applied. The intraobserver reproducibility study was excellent (interclass correlation coefficient >0.900), and the interobserver reproducibility study was good (interclass correlation coefficient >0.700). The data regression analysis showed that cycle time, filling time, isovolumetric contraction time, and filling time fraction increased with gestational age, whereas ejection time fraction decreased with gestational age and myocardial performance index (mean, 0.43±0.08), isovolumetric relaxation time (mean, 0.04±0.01), and ejection time (mean, 0.16±0.01) remained constant from 11 to 13 weeks.

CONCLUSION

The study of fetal cardiac function is feasible and reproducible at 11 to 13+6 gestational weeks. Nomograms of the studied parameters are provided.

Evaluation of Fetal Cardiac Output and Modified Myocardial Performance Index in Pregnant Women with Idiopathic Polyhydramnios: A Case Control Study from a Tertiary Hospital

PURPOSE

This study aimed to investigate fetal cardiac output and myocardial performance index in pregnant women with idiopathic polyhydramnios and compare them to healthy pregnant women.

METHODS

Thirty patients admitted to Ankara City Hospital at 24-39 weeks of gestation with idiopathic polyhydramnios were included as the study group. Clinical characteristics, fetal cardiac output, and fetal modified myocardial performance index (Mod-MPI) were compared between the groups.

RESULTS

The combined cardiac output (CCO), left cardiac output (LCO), right cardiac output (RCO), pulmonary artery velocity time integral (PA-VTI), and aortic VTI were statistically significantly higher in the study group (p=0.003, p=0.028, p=0.002, p=0.000, and p=0.017, respectively).The idiopathic polyhydramnios group had a significantly higher Mod-MPI and isovolumetric contraction time (ICT) and a significantly lower ejection time (ET) compared to the controls (p=000, p=0.003, and p=0.023, respectively). In the idiopathic polyhydramnios group, the aortic max (p=0.009) and aortic VTI (p=0.047) values were significantly lower and the left ventricular outflow tract isovolumetric relaxation time (LVOT-IRT) (p=0.021) was significantly higher in cases where the NICU was required. According to the ROC analysis performed in the idiopathic polyhydramnios group, the optimal cut-off values of aortic max, aortic VTI, and LVOT-IRT in the prediction of the NICU requirement were (57.5, 0.089 and 41.5, respective cut-off value) (p=0.010, p=0.048, p=0.021, respectively).

CONCLUSIONS

Both fetal cardiac output and Mod-MPI values were altered in fetuses with idiopathic polyhydramnios.

Decreased fetal cardiac output in pregnant women with severe SARS-Cov-2 infection

AIM

We aimed to examine fetal cardiac output (CO) in patients who recovered from severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection.

MATERIALS

This prospective study included 48 pregnant women recovered from SARS-CoV-2 infection and 50 control cases. SARS-CoV-2 infection was diagnosed by polymerase chain reaction (PCR) test in patients. Fetal echocardiographic evaluations were performed at 24-37 weeks of gestation in pregnant women who recovered from the infection and control group.

RESULTS

The median value of ultrasound evaluation was 34 (2.6) weeks of gestation in the recovery from the SARS-CoV-2 infection (RSI) group, and 32 (7.6) weeks in the control group (p = .565). Left cardiac output (LCO) z score was significantly lower in the RSI group than the control group (p = .041). LCO and combine cardiac output (CCO) z score were significantly lower in the severe disease group than mild, moderate disease groups, and controls (p = .019 and p = .013). CCO (ml/min/kg) was decreased in the severe disease group when compared with control and mild disease groups (p = .044).

CONCLUSION

In the present study, fetal cardiac output in pregnant women who recovered from SARS-CoV-2 infection was found to be significantly reduced in those with severe disease, while there was no significant difference in mild and moderate cases. Placental dysfunction and inflammatory cytokines might cause fetal cardiac changes. Further studies could be clarified on the impact of SARS-CoV-2 infection on fetal cardiac function.

Z-score of some pulsed-wave Doppler indices of right pulmonary artery segments of normal fetuses in the second and third trimestries

OBJECTIVE

To establish the Z-score equation of right pulmonary artery (RPA) segments for some valuable pulse-wave Doppler parameters (PWD) and estimate their reference ranges in normal fetuses.

METHODS

Two hundred and seventy-three normal singleton fetuses at 18-38 weeks were enrolled in this fetal echocardiography of a prospective cross-sectional study. The proximal, middle, and distal segments of RPA of pulsed-wave Doppler parameters, such as peak systolic velocity (PSV) and pulsation index (PI) were obtained by using fetal Doppler echocardiography. The mean and standard deviation (SD) of each parameter and gestational age (GA) were analyzed by regression, and the optimal model of Z-score was established.

RESULTS

There was a significant correlation between fetal pulmonary artery Doppler parameters and gestational age, during the whole pregnancy, PI showed a downward trend with the progress of gestational week, while PSV showed an upward trend. Whether it was the original data or the data converted for the normal distribution of Z-score, the model that best described the mean value of parameters was quadratic regression. The SDs for PSV of the middle segment was a linear equation, others were constants. From proximal to distal of RPA, PSV showed a decreasing trend while PI showed an increasing trend.

CONCLUSION

Z-score models and reference values for some PWD parameters of three segments of RPA were proposed against GA, which may quantitatively assess the flow dynamics of fetal RPA and quantitatively assess fetal lung circulation development and hemodynamic changes.

Fetal cardiac filling and ejection time fractions by pulsed-wave Doppler: reference ranges and potential clinical application

OBJECTIVES

Fetal cardiac function can be evaluated using a variety of parameters. Among these, cardiac cycle time-related parameters, such as filling time fraction (FTF) and ejection time fraction (ETF), are promising but rarely studied. We aimed to report the feasibility and reproducibility of fetal FTF and ETF measurements using pulsed-wave Doppler, to provide reference ranges for fetal FTF and ETF, after evaluating their relationship with heart rate (HR), gestational age (GA) and estimated fetal weight (EFW), and to evaluate their potential clinical utility in selected fetal conditions.

METHODS

This study included a low-risk prospective cohort of singleton pregnancies and a high-risk population of fetuses with severe twin-twin transfusion syndrome (TTTS), aortic stenosis (AoS) or aortic coarctation (CoA), from 18 to 41 weeks' gestation. Left ventricular (LV) and right ventricular inflow and outflow pulsed-wave Doppler signals were analyzed, using valve clicks as landmarks. FTF was calculated as: (filling time/cycle time) × 100. ETF was calculated as: (ejection time/cycle time) × 100. Intraclass correlation coefficients (ICC) were used to evaluate the intra- and interobserver reproducibility of FTF and ETF measurements in low-risk fetuses. The relationships of FTF and ETF with HR, GA and EFW were evaluated using multivariate regression analysis. Reference ranges for FTF and ETF were then constructed using the low-risk population. Z-scores of FTF and ETF in the high-risk fetuses were calculated and analyzed.

RESULTS

In total, 602 low-risk singleton pregnancies and 54 high-risk fetuses (nine pairs of monochorionic twins with severe TTTS, 16 fetuses with AoS and 20 fetuses with CoA) were included. Adequate Doppler traces for FTF and ETF could be obtained in 95% of low-risk cases. Intraobserver reproducibility was good to excellent (ICC, 0.831-0.905) and interobserver reproducibility was good (ICC, 0.801-0.837) for measurements of all timing parameters analyzed. Multivariate analysis of FTF and ETF in relation to HR, GA and EFW in low-risk fetuses identified HR as the only variable predictive of FTF, while ETF was dependent on both HR and GA. FTF increased with decreasing HR in low-risk fetuses, while ETF showed the opposite behavior, decreasing with decreasing HR. Most recipient twins with severe TTTS showed reduced FTF and preserved ETF. AoS was associated with decreased FTF and increased ETF in the LV, with seemingly different patterns associated with univentricular vs biventricular postnatal outcome. The majority of fetuses with CoA had FTF and ETF within the normal range in both ventricles.

CONCLUSIONS

Measurement of FTF and ETF using pulsed-wave Doppler is feasible and reproducible in the fetus. The presented reference ranges account for associations of FTF with HR and of ETF with HR and GA. These time fractions are potentially useful for clinical monitoring of cardiac function in severe TTTS, AoS and other fetal conditions overloading the heart. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Reference Ranges for Pulsed-Wave Doppler of the Fetal Cardiac Inflow and Outflow Tracts from 13 to 36 Weeks' Gestation

BACKGROUND

Doppler assessment of ventricular filling and outflow tract velocities is an integral part of fetal echocardiography, to assess diastolic function, systolic function, and outflow tract obstruction. There is a paucity of prospective data from a large sample of normal fetuses in the published literature. The authors report reference ranges for pulsed-wave Doppler flow of the mitral valve, tricuspid valve, aortic valve, and pulmonary valve, as well as heart rate, in a large number of fetuses prospectively examined at a single tertiary fetal cardiology center.

METHODS

The study population comprised 7,885 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective pulsed-wave Doppler blood flow measurements were taken of the mitral, tricuspid, aortic, and pulmonary valves. The fetal heart rate was recorded at the time of each assessment. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age.

RESULTS

The measurement for each cardiac Doppler measurement was expressed as a Z score (difference between observed and expected values divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac inflow and outflow tracts.

CONCLUSIONS

This study establishes reference ranges for fetal cardiac Doppler measurements and heart rate between 13 to 36 weeks' gestation that may be useful in clinical practice.

Referential Values of Testicular Volume Measured by Ultrasonography in Normal Children and Adolescents: Z-Score Establishment

Objective: To establish Z-score regression equation derived from age for testicular volume measured by ultrasonography in normal boys aged 0 to 18 years old. Method: The length (L), width (W), and height (H) of 3,328 testicles from 1,664 Chinese boys were measured by ultrasonography. Lambert's formula: L × W × H × 0.71 was used to calculate testicular volume. Z-score regression equation derived from age was established by regression analysis of predicted values of testicular volume and standard deviations. Result: There was no significant difference between left and right testicular volumes. Testicular volume was positively correlated with age, and logarithmic transformation of testicular volume can show a fine curve fit with age. To establish Z-score regression equation derived from age, the predicted values of testicular volume used cubic regression equations, and the standard deviation used square regression equations. The Z-score regression equation derived from age was calculated by the formula: z = [lg (L × W × H × 0.71) - (-0.3524-0.01759 × x+0.009417 × x2-0.0001840 × x3)]/(0.1059+0.01434 × x-0.0005324 × x2). Conclusion: The current study provided a reference value for testicular volume of boys aged 0 to 18 years old. Z-score regression equation derived from age for testicular volume can be established. Z-score will be of great value for the testicular development assessment and disease diagnosis and follow-up.

Development of the Z-score for the measurement of myocardial thickness by two-dimensional echocardiography in normal fetuses

BACKGROUND

In the current literature, there is a tendency to describe normal values of echocardiographic measurements by means of the Z-score. In fetal cardiology, these Z-score equations are still being established. Measurement of myocardial thickness is an important assessment, especially in fetuses of diabetic mothers, because of the risk of developing myocardial hypertrophy secondary to elevated maternal blood glucose levels.

OBJECTIVE

To determine the percentiles and to develop the Z-score equations of right and left ventricular lateral walls and interventricular septum measurements using two-dimensional echocardiography in normal fetuses between 24 and 34 weeks of gestation.

METHODS

This is a prospective cross-sectional study that was performed in single fetuses with normal heart from nondiabetic pregnant women. Measurements of the lateral walls of the right and left ventricles and the interventricular septum were made.

RESULTS

Eight hundred and seventy three pregnant women were included. We determined the percentiles of the measurements for each gestational age. The Z-score equation was developed for each of the measurements: right ventricular lateral wall measurement [RVLW = x-(-1 + 0.109 * GA)/0.4], left ventricle lateral wall measurement [LVLW = x-(-1.366 + 0.12 * GA)/0.43], and interventricular septum, both at the four-chamber view [IVS_4ch = (x-(-1.113 + 0.107 * GA)/0.4] and at the left ventricular outflow tract plane [IVS_LVOT = (x-(-0.581 + 0.084 * GA)/0.35].

CONCLUSION

The present study allowed the demonstration of the percentiles and the Z-score equations for each of the measurements studied.

Fetal cardiac function by three-dimensional ultrasound using 4D-STIC and VOCAL - an update

Three- and four-dimensional (3D/4D) ultrasonography with spatio-temporal image correlation (4D-STIC) allows obtaining fetal cardiac volumes and their static and real-time analysis in multiplanar and rendering modes. Cardiac biometrics and Doppler-echocardiographic parameters for evaluation of fetal heart function, including cardiac output and stroke volume, can be analyzed using M-mode, two-dimensional (2D), and 3D/4D cardiac ultrasound. In recent years, functional echocardiography has been used to study fetuses without a structurally cardiac defect but who are at risk of heart failure due to the presence of extra-cardiac conditions, such as, fetal growth restriction, tumors/masses, twin-to-twin transfusion syndrome, fetal anemia (Rh alloimmunization), congenital infections, or maternal diabetes mellitus. The assessment of cardiac function provides important information on hemodynamic status and can help optimize the best time for delivery and reduce perinatal morbidity and mortality. Since 2003, with the advent of the 4D-STIC software, it is possible to evaluate the fetal heart in multiplanar, and rendering modes. This technology associated with virtual organ computer-aided analysis (VOCAL) enables determining the ventricular volume (end-diastole, end-systole), the stroke-volume, the ejection fraction, and the cardiac output of each ventricle. Since 2004, several studies demonstrated that the 4D-STIC and VOCAL had good reproducibility to measure cardiac volumes This study reviews published studies that evaluated the fetal cardiac function by 3D ultrasound using 4D-STIC and VOCAL software.

Medical Diagnostic Tests: A Review of Test Anatomy, Phases, and Statistical Treatment of Data

Diagnostic tests are approaches used in clinical practice to identify with high accuracy the disease of a particular patient and thus to provide early and proper treatment. Reporting high-quality results of diagnostic tests, for both basic and advanced methods, is solely the responsibility of the authors. Despite the existence of recommendation and standards regarding the content or format of statistical aspects, the quality of what and how the statistic is reported when a diagnostic test is assessed varied from excellent to very poor. This article briefly reviews the steps in the evaluation of a diagnostic test from the anatomy, to the role in clinical practice, and to the statistical methods used to show their performances. The statistical approaches are linked with the phase, clinical question, and objective and are accompanied by examples. More details are provided for phase I and II studies while the statistical treatment of phase III and IV is just briefly presented. Several free online resources useful in the calculation of some statistics are also given.