Normal fetal lung volume measured with three-dimensional ultrasound.

OBJECTIVES: To construct reference intervals for fetal lung volumes measured longitudinally using three-dimensional (3D) ultrasound, and to evaluate the effect of gender on lung size. METHODS: This was a prospective, longitudinal study in the obstetric outpatient department of the VU University Medical Center, Amsterdam. Seventy-eight women with uncomplicated pregnancies were scanned three to four times at gestational ages of 18-34 weeks. 3D models of the lung were constructed using the ultrasound machine's software. After the infants were delivered the entire group was reanalyzed with regard to fetal gender. Centiles for the lung volumes of the entire group and for each gender separately were estimated using multilevel modeling. RESULTS: Charts and tables of right and left fetal lung volumes, using gestational age and estimated fetal weight as the independent variables, are presented. There was a significant difference in lung volume between male and female fetuses at each gestational age. Charts and tables of right and left fetal lung volumes for each gender at gestational ages of 18-34 weeks are also presented. CONCLUSIONS: We present valid references for volumetric measurements of the right and left fetal lungs in male and female fetuses. The feasibility and reliability of fetal lung volume measurements using 3D ultrasound is good.     

Relationship between lung area at ultrasound examination and lung volume assessment with magnetic resonance imaging in isolated congenital diaphragmatic hernia.

OBJECTIVES: To prospectively examine the relationship between contralateral lung area measured by two-dimensional (2D) ultrasound examination and contralateral and total fetal lung volume (FLV) estimated by magnetic resonance imaging (MRI) in the assessment of fetuses with congenital diaphragmatic hernia (CDH). METHODS: Sixty-six fetuses with isolated CDH were entered in this prospective study. Contralateral fetal lung area was measured by 2D ultrasonography using the longest axis method. Ipsilateral, contralateral and total FLV were measured using multiplanar axial T2-weighted MRI. Regression analysis was used to determine the significance of associations between contralateral lung area and contralateral and total FLV, and the predicted total FLV was subsequently calculated using the regression equation. Univariate regression analysis was used to investigate the effect on the proportionate difference between the predicted and the observed total FLV of gestational age, proportionate volume of ipsilateral vs. total FLV, side of CDH, intrathoracic herniation of the liver and intratracheal presence of a balloon. RESULTS: The 66 fetuses underwent a total of 191 paired 2D ultrasound and MRI examinations at a median gestational age of 30 (range, 18-38) weeks. It was possible to visualize and measure the contralateral lung area by 2D ultrasound, as well as both the ipsilateral and contralateral lung volumes by MRI, in all instances. There was a significant association between contralateral lung area and contralateral lung volume (r = 0.86; P < 0.001) and with total FLV (r = 0.84; P < 0.001). Univariate regression analysis showed that the proportionate difference between the predicted and the observed total FLV was significantly associated with the proportionate volume of ipsilateral vs. total FLV but not with gestational age, side of CDH, intrathoracic herniation of the liver or intratracheal presence of the balloon. CONCLUSIONS: In CDH, contralateral lung area measurement by 2D ultrasound correlates well with the total FLV estimated by MRI, irrespective of gestational age, liver herniation or side of herniation. Inconsistencies between the two measurements are attributable to the contribution of the ipsilateral lung to the total lung volume.     

Fetal lung volume estimated by 3-dimensional ultrasonography and magnetic resonance imaging in cases with isolated congenital diaphragmatic hernia.

OBJECTIVE: To assess the agreement of 3-dimensional ultrasonography and magnetic resonance imaging in estimating fetal lung volume in cases with isolated congenital diaphragmatic hernia. METHODS: Fetal lung volume was measured in 11 cases of congenital diaphragmatic hernia (10 left and 1 right) by 3-dimensional ultrasonography and magnetic resonance imaging. These examinations were performed during the same week. The operators were blinded to each other's results. Intraclass correlation was used to evaluate the agreement between 3-dimensional ultrasonography and magnetic resonance imaging estimations of the ipsilateral, contralateral, and total fetal lung volume. A Bland-Altman graph was plotted to detect possible discordant observations. RESULTS: The global intraclass correlation coefficient between magnetic resonance imaging and 3-dimensional ultrasonographic measurement of fetal lung volume was 0.94 (95% confidence interval, 0.78-0.98) with no outliers observed on the Bland-Altman plot. CONCLUSIONS: There is a good agreement between 3-dimensional ultrasonography and magnetic resonance imaging for fetal lung volume estimation in cases with congenital diaphragmatic hernia.     

Lung and heart volumes by three-dimensional ultrasound in normal fetuses at 12-32 weeks' gestation.

OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.     

The use of inversion mode and 3D manual segmentation in volume measurement of fetal fluid-filled structures: comparison with Virtual Organ Computer-aided AnaLysis (VOCAL)

OBJECTIVE: Volume measurements by three-dimensional (3D) ultrasonography are considered more accurate than those performed by two-dimensional (2D) ultrasonography. The purpose of this study was to compare the agreement of three techniques, as well as the inter- and intraobserver agreements for volume measurements of fetal fluid-filled structures. METHODS: Fifty 3D volume datasets of fetal stomachs and bladders were explored. Volume measurements were performed independently by two observers using: (1) Virtual Organ Computer-aided AnaLysis (VOCAL); (2) inversion mode; and (3) 'manual segmentation'. Reliability was evaluated using intraclass correlation coefficient (ICC), and Bland-Altman plots were generated to examine bias and agreement. The time required to complete the measurements was compared using Student's t-test or the Wilcoxon Signed Rank Test, and P-values < 0.025 or < 0.05 were considered statistically significant. RESULTS: All volume datasets could be measured using the three techniques. A high degree of reliability was observed between: (1) VOCAL and inversion mode (ICC, 0.995; 95% CI, 0.992-0.997); (2) VOCAL and manual segmentation (ICC, 0.997; 95% CI, 0.995-0.998); and (3) inversion mode and manual segmentation (ICC, 0.995; 95% CI, 0.992-0.997). There was good agreement between VOCAL and inversion mode (mean, - 2.4%; 95% limits of agreement, - 20.1 to 15.3%), VOCAL and manual segmentation (mean, - 8.3%; 95% limits of agreement, - 28.8 to 12.2%) as well as between inversion mode and manual segmentation (mean, 5.9%, 95% limits of agreement: - 14.3 to 26%). Manual segmentation and inversion mode measurements were obtained significantly faster than those by VOCAL. CONCLUSIONS: Volume measurements of fetal fluid-filled structures of relatively regular shape with inversion mode and manual segmentation are feasible. Both techniques have good agreement with VOCAL and are significantly faster than VOCAL. Inversion mode is a reliable method for volume calculations of fluid-filled organs, whereas manual segmentation can be used when volume measurements by VOCAL or inversion mode are technically difficult to obtain, such as solid structures with poorly defined borders as the volume dataset is rotated, like the uterine cervix.     

Prenatal ultrasonographic prediction of the umbilical coiling index at birth and adverse pregnancy outcome.

OBJECTIVES: To evaluate whether the antenatal umbilical coiling index (aUCI) as measured by ultrasonography predicts the postnatal umbilical coiling index (pUCI) and adverse pregnancy outcome. METHODS: In a prospective study in 117 pregnancies, the aUCI was measured between 28 weeks and term by ultrasonography. The aUCI was calculated as the reciprocal value of the mean pitch of one complete coil. The pUCI was calculated as the number of coils divided by the cord length in cm. The correlation between aUCI and pUCI was assessed and likelihood ratios for adverse pregnancy outcome were calculated. RESULTS: We had complete data on 81 subjects. Mean aUCI +/- SD was 0.30 +/- 0.09 and mean pUCI +/- SD was 0.17 +/- 0.08. The correlation coefficient between aUCI and pUCI was 0.66, P < 0.001. Limits of agreement were 0-0.28 coils/cm. The positive likelihood ratio for small-for-gestational-age infants was 2.6 (95% confidence interval (CI) 0.6-11.6) for ultrasound hypocoiling, and 5.7 (95% CI 1.3-24.8) for ultrasound hypercoiling. The positive likelihood ratio for interventional delivery for non-reassuring fetal status was 1.2 (95% CI 0.2-9.0) for ultrasound hypocoiling, and 10.3 (95% CI 2.1-50.2) for ultrasound hypercoiling. CONCLUSIONS: Strong correlation coefficients comparing the aUCI and pUCI do not reflect agreement. Since the limits of agreement were almost as wide as the full range for the pUCI, the aUCI does not predict the pUCI with sufficient precision. Larger prospective studies are required to confirm the predictive potential of the aUCI for adverse pregnancy outcome.     

Measurement of fetal nuchal translucency thickness by three-dimensional ultrasound.

OBJECTIVE: To investigate the feasibility and repeatability of nuchal translucency thickness measurement using three-dimensional ultrasound. METHODS: Forty consecutive women with uncomplicated singleton pregnancies attending for Down syndrome screening at 11-14 weeks' gestation were included in this prospective crossover trial. Nuchal translucency thickness was measured using both two-dimensional and three-dimensional ultrasound. In each case two three-dimensional volumes were recorded and then examined by using the technique of planar reformatted sections. The initial plane of the first volume always contained a clear image of the nuchal region ('sagittal volume'), whilst the initial plane of the second volume was selected randomly regardless of fetal position ('random volume'). The repeatability of nuchal translucency measurement was examined by constructing a scatter diagram of the difference between the measurements plotted against the mean of two readings. RESULTS: Nuchal translucency measurements could be repeated in 38/40 (95%) sagittal volumes and 24/40 (60%) random volumes. The mean difference between two-dimensional measurements and those obtained by reslicing of sagittal three-dimensional volumes was -0.097 mm (95% limits of agreement from -0.481 to 0.675) and 0.225 mm (95% limits of agreement from -0.369 to 0.819) when random volumes were examined. CONCLUSIONS: Reslicing of stored three-dimensional volumes can be used to replicate nuchal translucency measurements only when nuchal skin can also be clearly seen on two-dimensional ultrasound.     

三维超声对胎儿肺体积的研究

目的 应用三维超声建立不同孕周胎儿左肺、右肺及总肺体积的正常参考值范围.方法 对正常单胎妊娠16～37周324例胎儿进行肺三维超声体积扫查,采用VOCAL分析软件30°旋转法分别测定左肺及右肺体积,应用相关回归分析拟合左肺、右肺及总肺体积随孕周增长的回归方程.结果 正常妊娠胎儿左肺、右肺及总肺体积三维超声测量值均与孕周高度相关(左肺:r=0.966,P＜0.001;右肺:r=0.973,P＜0.001;总肺:r=0.990,P＜0.001).左肺、右肺及总肺体积随孕周增长的最适方程均为指数曲线回归方程(左肺:y=0.207exp~(0.143X),右肺:y=0.301exp~(0.14X),总肺:y=0.508exp~(0.142X)).结论 三维超声测量16～37周胎儿肺体积的正常参考值为产前诊断肺发育不良提供有价值的参考指标.     

A nomogram of fetal lung volumes estimated by 3-dimensional ultrasonography using the rotational technique (virtual organ computer-aided analysis).

OBJECTIVE: The purpose of this study was to build a nomogram of normal fetal lung volumes throughout gestational age estimated by 3-dimensional ultrasonography using the rotational technique (Virtual Organ Computer-Aided Analysis [VOCAL]; GE Healthcare, Kretztechnik, Zipf, Austria). METHODS: Fetal lung volume was assessed in 146 healthy fetuses by 3-dimensional ultrasonography using the technique of rotation of the multiplanar imaging (VOCAL). Inclusion criteria were healthy women with singleton normal pregnancies, normal fetal morphologic ultrasonographic findings, reliable dating established by dates and by ultrasonographic measurement of the crown-lump length in the first trimester, and gestational age from 20 to 37 weeks. Exclusion criteria were discordance between clinical and ultrasonographic dating, patients lost to follow-up, and birth weight disorders. Each patient was scanned once during pregnancy. RESULTS: The right, left, and total mean pulmonary volumes ranged, respectively, from 5.37, 4.66, and 9.95 cm3 at 20 weeks to 46.06, 37.34, and 84.35 cm3 at 37 weeks. The logistic transformation analysis yielded the following formulas: right lung volume = exp(4.07/[1 + exp(21.90 - gestational age/5.44)]); left lung volume = exp(3.82/(1 + exp[22.03 - gestational age/5.17)]); and, total lung volume = exp(4.72/[1 + exp(20.30 - gestational age/6.05)]). CONCLUSIONS: A new nomogram of fetal lung (right, left, and total) volumes throughout gestational age using the rotational technique (VOCAL) is described, and reference values have been generated.     

Repeatability and Reproducibility of Fetal Cardiac Ventricular Volume Calculations Using Spatiotemporal Image Correlation and Virtual Organ Computer‐Aided Analysis

Objective. The objective of this study was to quantify the repeatability and reproducibility of fetal cardiac ventricular volumes obtained using spatiotemporal image correlation (STIC) and Virtual Organ Computer‐Aided Analysis (VOCAL; GE Healthcare, Kretztechnik, Zipf, Austria). Methods. A technique was developed to compute ventricular volumes using the subfeature Contour Finder: Trace. Twenty‐five normal pregnancies were evaluated for the following: (1) to compare the coefficient of variation (CV) of ventricular volumes obtained using 15° and 30° rotation; (2) to compare the CV between 3 methods of quantifying ventricular volumes: (a) Manual Trace, (b) Inversion Mode, and (c) Contour Finder: Trace; and (3) to determine repeatability by calculating agreement and reliability of ventricular volumes when each STIC was measured twice by 3 observers. Reproducibility was assessed by obtaining 2 STICs from each of 44 normal pregnancies. For each STIC, 2 ventricular volume calculations were performed, and agreement and reliability were evaluated. Additionally, measurement error was examined. Results. (1) Agreement was better with 15° rotation than 30° (15°: 3.6%; 95% confidence interval [CI], 3.0%–4.2%; versus 30°: 7.1%; 95% CI, 5.8%–8.6%; P < .001); (2) ventricular volumes obtained with Contour Finder: Trace had better agreement than those obtained using either Inversion Mode (Contour Finder: Trace: 3.6%; 95% CI, 3.0%–4.2%; versus Inversion Mode: 6.0%; 95% CI, 4.9%–7.2%; P < .001) or Manual Trace (10.5%; 95% CI, 8.7%–12.5%; P < .001); (3) ventricular volumes were repeatable with good agreement and excellent reliability for both intraobserver and interobserver measurements; and (4) ventricular volumes were reproducible with negligible differences in agreement and good reliability. In addition, bias between STIC acquisitions was minimal (<1%; mean percent difference, ?0.4%; 95% limits of agreement, ?5.4%–5.9%). Conclusions. Fetal echocardiography using STIC and VOCAL allows repeatable and reproducible calculation of ventricular volumes with the subfeature Contour Finder: Trace.     

Right-sided cardiac function in healthy volunteers measured by first-pass radionuclide ventriculography and gated blood-pool SPECT: comparison with cine MRI

BACKGROUND: Right ventricular (RV) function is of interest in an array of cardiopulmonary diseases. First-pass radionuclide ventriculography (FP), gated blood-pool single photon emission tomography (GBPS) and cardiac magnetic resonance imaging (MRI) are three currently used non-invasive methods for evaluation of right-sided cardiac function. The aim of our study was to compare the agreement between these methods when measuring right-sided cardiac function. METHODS: Twenty-four healthy volunteers were included. Mean age was 44 years (range: 25-60) and 29% were females. All participants had FP, GBPS and breath-hold cine MRI performed according to standard protocols. RESULTS: Normal ranges for RV ejection fraction (RVEF) defined as mean +/- 2SD were 0.49-0.72, 0.44-0.66 and 0.40-0.69 when measured by MRI, FP and GBPS respectively. Bland-Altman analysis showed a mean difference (bias) between MRI and FP of 0.05 (95% CI: 0.03-0.08) and of 0.06 (95% CI: 0.02-0.10) between MRI and GBPS. No systematic bias was found between FP and GBPS. Normal values for RV end-diastolic volume index (RVEDVI) were 37-95 and 29-91 ml m(-2) when measured by MRI and GBPS respectively. The mean difference between RVEDVI was 6 ml m(-2) (95% CI: 0-11). CONCLUSIONS: (i) Normal values of RVEF differ between MRI, FP and GBPS with wide limits of agreement, accordingly it is difficult to evaluate changes over time if measured by different methods, (ii) RV volumes are in the same range when measured by MRI or GBPS but with wide limits of agreement, and (iii) if MRI is considered gold standard then FP is more accurate than GBPS for RVEF measurements.     

Reproducibility of fetal lung volume measurements with 3-dimensional ultrasonography.

OBJECTIVE: To build a nomogram of normal fetal lung volumes and to assess the reproducibility of measurements using 3-dimensional ultrasonography. METHODS: Inclusion criteria were healthy women, singleton normal pregnancies, reliable dating, and 20 to 30 weeks' gestation. Exclusion criteria were discordance between clinical and ultrasonographic dating, patients lost to follow-up, and birth weight disorders. Patients were scanned at intervals longer than 2 weeks. Three volumes were acquired for each patient; only data from the volume with the best image quality was used for analysis. Volumes were rated and measured by the manual tracing method. We recorded whether the clavicle was visualized. Only good-quality volumes were included in analysis. The best volume was chosen, and each lung was measured. RESULTS: A total of 75 patients were studied over a 9-month period, from which 182 volumes were analyzed. Of the 182 volumes, 15 (8.2%) were excluded for poor quality. The remaining 167 volumes were included in the final analysis. In 83 volumes (50%), the clavicle was not visualized. The best fit for total lung volume was a second-degree polynomial regression curve. Lung volume was 10.28 mL at 20 weeks and 51.49 mL at 30 weeks. Assessment of agreement was studied by selection of 40 volumes. Intraobserver variability was 5.48 mL (10.6%) and 3.07 mL (5.96%). Interobserver variability was 7 mL. CONCLUSIONS: Our findings suggest that 3-dimensional ultrasonographically derived measurements are reliable and reproducible up to 30 weeks if a standard measurement technique is used.     

Role of Sonographic Automatic Volume Calculation in Measuring Fetal Cardiac Ventricular Volumes Using 4‐Dimensional Sonography

Objective. The purpose of this study was to compare the agreement and reliability of virtual organ computer‐aided analysis (VOCAL) and sonographic automatic volume calculation (sonoAVC) for measurements of ventricular volume from fetal heart data sets acquired by 4‐dimensional sonography with spatiotemporal image correlation (STIC). Methods. We studied 45 volumes from fetuses with normal (n = 30) and abnormal (n = 15) hearts. Spatiotemporal image correlation data sets were frozen in end systole and end diastole, and ventricular volumes were measured with VOCAL and sonoAVC. The stroke volume was calculated from these measurements. Reliability and agreement of the two techniques were evaluated with intraclass correlation coefficients (ICCs), and proportionate Bland‐Altman plots were constructed. The time necessary to complete the measurements with either technique was compared. Intraobserver and interobserver agreement of measurements was calculated. Results. All data sets could be measured with both techniques. A high degree of reliability was observed between VOCAL and sonoAVC (left ventricular stroke volume ICC, 0.978; 95% confidence interval [CI], 0.957–0.989; right ventricular stroke volume ICC, 0.985; 95% CI, 0.972–0.992). The time necessary to measure the stroke volume was significantly shorter with sonoAVC (2.8 versus 11.7 minutes; P < .0001) than with VOCAL. Bland‐Altman tests showed no clinically significant mean percent differences between stroke volume measurements obtained from each ventricle by the same observer or by 2 independent observers using either VOCAL or sonoAVC. Conclusions. There was good agreement between cardiac volumes measured with VOCAL and sonoAVC. Sonographic automatic volume calculation represents a rapid technique for estimating fetal stroke volume and promises to become the method of choice.     

Accuracy of fetal lung volume assessed by three-dimensional sonography.

OBJECTIVE: To determine the accuracy and precision of prenatal three-dimensional (3D) ultrasound in estimating fetal lung volume using the rotational multiplanar technique (VOCAL) by comparing it to postmortem volume measurements. METHODS: Fetal lung volume was measured during 3D ultrasound examination using a rotational multiplanar technique in eight cases of congenital diaphragmatic hernia (CDH) (six left and two right-sided) and in 25 controls without pulmonary malformation, immediately before termination. Prenatal 3D sonographic estimates of fetal lung volume were compared with postmortem measurement of fetal lung volume achieved by water displacement. RESULTS: The intraclass correlation coefficient of fetal lung volume estimated by 3D ultrasound and measured at postmortem examination was 0.95 in CDH cases and 0.99 in controls. Based on Bland-Altman analysis, the bias, precision and limits of agreement were, respectively, 0.35 cm(3), 1.46 cm(3) and between -2.51 and + 3.21 cm(3) in cases with CDH and 0.08 cm(3), 2.80 cm(3) and between -5.41 and + 5.57 cm(3) in controls. The mean relative error of 3D ultrasound fetal lung volume measurement was -7.19% (from -42.70% to + 18.11%) in CDH cases and -0.72% (from -30.25% to + 19.22%) in controls, while the mean absolute error of 3D ultrasound fetal lung volume measurement was 1.40 (range, 0.71-2.52) cm(3) and 2.12 (range, 0.05-4.98) cm(3), respectively. Accuracy of 3D ultrasound for measuring fetal lung volumes was 84.86 (range, 57.30-99.48)% in cases with CDH and 91.38 (range, 69.75-99.45)% in controls. The mean intraobserver variability for lung volume estimated by 3D ultrasound was 0.28 cm(3) in controls and 0.17 cm(3) in CDH cases. CONCLUSION: Prenatal 3D ultrasound can estimate accurately fetal lung volume using the rotational multiplanar technique for volume measurements (VOCAL), even in fetuses with very small lungs, such as cases with isolated CDH.     

Three-dimensional ultrasound fetal lung volume measurement: a systematic study comparing the multiplanar method with the rotational (VOCAL) technique.

OBJECTIVES: This study was designed to compare a conventional multiplanar technique for three-dimensional (3D) ultrasound measurement of fetal lung volume with a rotational method using VOCAL trade mark (Virtual Organ Computer-aided AnaLysis). METHODS: Thirty-two fetuses with a variety of conditions at risk for pulmonary hypoplasia were studied. 3D volume data sets of the fetal lungs were acquired using a commercially available ultrasound system. The right and left lung volumes were calculated separately using VOCAL and the multiplanar technique. The level of agreement between two independent observers in categorizing the 3D volume data set as measurable or non-measurable was determined. The interobserver and intermethod variabilities were also evaluated for both methods. RESULTS: The intermethod variability was excellent (correlation r = 0.93 and r = 0.96 for the left and right lung, respectively), and there was substantial agreement between the results of both approaches (limits of agreement - 4.4 to 8.9 and - 3.4 to 4.8 mL for the right and left lung, respectively). Fetal lung estimation with VOCAL had a significantly higher interobserver variability than the multiplanar technique. Interobserver agreement in categorizing lung volume data sets as measurable or non-measurable was lower when VOCAL was used. CONCLUSION: Fetal lung volume measurements can be undertaken interchangeably using the multiplanar technique or the rotational method with VOCAL. However, the latter was less reproducible (lower degree of agreement and significantly higher interobserver variability) than the former.     

比较超声和MRI评估正常胎儿胸廓发育

目的 比较超声和MRI评估正常胎儿胸廓发育的可重复性和一致性。方法 选取30胎正常胎儿,分别以超声和MRI测量胎儿胸廓横径、前后径、面积、胸围、胸廓体积和肺体积,采用组内相关系数（ICC）及Bland-Altman图分析同一医师及不同医师间测量结果的可重复性和一致性,以Pearson相关分析观察超声测量胎儿肺体积、胸廓体积与MRI测量值的相关性。结果 同一医师及不同医师以超声测量胎儿胸廓二维指标的可重复性和一致性均高于MRI,而以MRI测量胎儿胸廓体积和肺体积的可重复性和一致性均高于超声;同一医师以超声测量胎儿胸廓横径的可重复性最高[ICC=0.996 4,95%CI（0.992 5,0.998 3）],且一致性最高[界限宽度－0.004 7±0.057 3,95%CI（－0.026 1,0.016 7）]。超声与MRI测量胎儿肺体积和胸廓体积高度相关（r=0.915、0.957,P均<0.001）。结论 超声和MR均可评估正常胎儿胸廓发育,胎儿胸廓发育的二维指标测量超声优于MRI;三维指标测量MRI优于超声,但两者相关性高。     

Objective evaluation of sylvian fissure development by multiplanar 3-dimensional ultrasonography.

OBJECTIVE: Evaluation of fetal cerebral cortex sulcation is important for the pre-natal diagnosis of neuronal migration disorders. Although abnormal sylvian fissure morphologic features are frequently observed in these conditions, the diagnosis of an abnormal sylvian fissure relies on subjective interpretation of ultrasonographic images. This study was performed to develop an objective ultrasonographic parameter for sylvian fissure evaluation. METHODS: This cross-sectional study included 202 normal singleton pregnancies without fetal anomalies. Using multiplanar, 3-dimensional ultrasonography, the sylvian fissure midpoint was identified. The sylvian fissure-to-parietal bone distance (SPB) was measured from the midpoint to the inner surface of the parietal bone, perpendicular to the falx cerebri. Bland-Altman plots were used to determine intraobserver and interobserver agreement. Regression analysis was used to evaluate the correlation between SPB measurements and gestational age. RESULTS: Two hundred (99%) of 202 pregnancies had a visible sylvian fissure, identifiable as early as 12 weeks of gestation. The mean SPB values at 12 and 41 weeks were 2.1 and 14.3 mm, respectively. Intraobserver and interobserver mean differences between paired measurements were 0.01 mm (95% limits of agreement, -0.41 to 0.43 mm) and 0.05 mm (95% limits of agreement, -1.79 to 1.90 mm), respectively. A linear correlation was observed between the SPB and gestational age (multiple R=0.91; R2=0.82 [SPB = -2.85 + 0.42 x gestational age]). CONCLUSIONS: (1) The SPB can be reproducibly measured from 12 weeks of gestation to term; and (2) a strong positive correlation was observed between the SPB and gestational age.     

Fractional moving blood volume estimation in the fetal lung using power Doppler ultrasound: a reproducibility study.

OBJECTIVE: To evaluate the reproducibility of fractional moving blood volume (FMBV) estimation in the fetal lung using power Doppler ultrasound (PDU). METHODS: The lung blood perfusion of 20 normally grown singleton fetuses at 32-35 weeks of gestation was evaluated by two experienced observers using PDU. Each observer recorded two consecutive sequences of images from the posterior part of the fetal lung and calculated FMBV offline. FMBV expresses the percentage of blood movement within a defined region of interest (ROI). Repeatability and agreement were evaluated by means of the intraclass (intraCC) and interclass (interCC) correlation coefficients. RESULTS: FMBV was successfully evaluated in 17/20 fetuses by both observers (kappa index 0.82; 95% CI 0.51-0.93). The intraCC for repeatability for Observer A was 0.92 (95% CI 0.78-0.96), and for Observer B 0.90 (95% CI 0.74-0.96). The mean difference between the first and the second measurement was 0.7% (SD 4.5%). The interCC for repeatability over time and between the operators was 0.70 (95% CI 0.56-0.76) and the mean difference between the observers was 0.6% (SD 4.65%). The interCC for agreement was 0.92 (95% CI 0.84-0.95) and the mean difference in FMBV results when both observers analyzed the same sequences offline was 0.6% (SD 3.85%). CONCLUSION: In the hands of experienced operators, using a well-defined ROI and standard settings, FMBV estimation is a reproducible method of quantifying power Doppler signals recorded from fetal lung blood perfusion.     

Postmortem fetal organ volumetry using magnetic resonance imaging and comparison to organ weights at conventional autopsy.

OBJECTIVES: Following perinatal death, organ weights at autopsy may provide evidence of growth restriction and pulmonary hypoplasia. Whilst postmortem magnetic resonance imaging (MRI) may provide comparable information to autopsy about structural abnormalities, its ability to provide reproducible data about organ size has yet to be determined. We examined the feasibility of using postmortem MRI to provide estimates of organ size and weight. METHODS: Twenty-five fetuses of gestational age from 16 to 40 weeks underwent postmortem MRI prior to autopsy. Fetal lung, brain and liver volume estimations were performed by two observers using the stereology technique on postmortem MRI slices. Fetal lung, brain and liver weights were recorded at autopsy. Organ volume estimates and autopsy organ weights were compared using regression analysis, and estimates of fetal organ densities made. Interobserver variability was assessed using a Bland-Altman plot. Receiver-operating characteristics curve (ROC) analysis compared MRI brain : liver volume ratios to autopsy brain : liver weight ratios. RESULTS: A linear relationship between organ volume estimates and organ weight was observed. Estimated densities for the fetal brain, liver and lung were 1.08 g/cm(3), 1.15 g/cm(3) and 1.15 g/cm(3), respectively. Interobserver 5th and 95th percentile limits of agreement for fetal brain, liver and lung were - 5.4% to + 7.9%, - 11.8% to + 8.3% and - 14.3% to + 8.7%, respectively. For MRI organ volumes to detect a brain weight : liver weight ratio > or = 4, ROC analysis demonstrated an area under the curve of 0.61, with an optimal cut-off of 4.1. CONCLUSION: Postmortem MRI organ volumetry can be used to estimate weights of major fetal organs. This may increase the information obtained from a minimally-invasive perinatal autopsy, particularly in the context of pulmonary hypoplasia and intrauterine growth restriction, where differential organ growth plays a major part in assessment of the underlying pathology.     

Frontomaxillary facial angle in chromosomally normal fetuses at 11 + 0 to 13 + 6 weeks.

OBJECTIVE: To establish the normal range of the frontomaxillary facial (FMF) angle at 11 + 0 to 13 + 6 weeks of gestation. METHODS: In this prospective study, three-dimensional (3D) volumes of the fetal head were obtained from 500 pregnancies before fetal karyotyping by chorionic villus sampling (CVS), after screening by fetal nuchal translucency (NT) thickness and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks. Only cases with a normal karyotype were included in this study. The FMF angle was measured off-line. In a subgroup of 150 cases the FMF angle was measured using 2D ultrasound before obtaining a 3D volume. In 50 cases the 3D volumes were used to measure the FMF angle by the same examiner twice and by another examiner once. RESULTS: The mean FMF angle decreased with crown-rump length (CRL) from 84.3 degrees at CRL 45 mm to 76.5 degrees at CRL 84 mm. There was no significant association between the FMF angle and fetal NT or serum PAPP-A or beta-hCG. In the volumes with paired measurements, the difference between two measurements by the same or two sonographers was < 5% in 95% of the cases. In the cases with paired 3D and 2D ultrasound measurements, the difference in FMF angles was < 8% in 95% of the cases. CONCLUSIONS: At 11 + 0 to 13 + 6 weeks the FMF angle decreases with fetal CRL but is not related to fetal NT or serum biochemistry. The measurement is reproducible and the results obtained by 3D and 2D ultrasound are similar.