The interobserver reliability and validity of volume calculation from three-dimensional ultrasound datasets in the in vitro setting

The predictive value of first trimester fetal volume measurements, a prospective cohort study

OBJECTIVES

To determine if fetal volume (FV) measurements with three-dimensional ultrasound in the first trimester of pregnancy can detect the fetus at risk for preterm birth and/or low birth weight.

METHODS

In this prospective cohort study, 538 participants were included during the routine first trimester ultrasound examination. Volume measurements were performed with VOCAL (9°). Firstly, the relation between FV and gestational age for a set of participants with normal pregnancies (training set), was assessed using multiple linear regression analysis, which was then used to determine the expected normal values. Secondly, for a new set of participants with normal pregnancies and a set of participants with complicated pregnancies (preterm birth and/or low birth weight), i.e. the validation set, the observed fetal volumes (FVobserved) were compared with their expected normal values (FVexpected) and expressed as a percentage of the expected normal value. The difference in mean percentage was then assessed with independent-samples t-test. Finally, logistic regression analysis was applied to the validation set to analyze the ability to predict the pregnancy outcome with FV calculation.

RESULTS

Linear regression analysis of FV as a predictor of preterm birth and/or low birth weight did not result in significant (p=0.630 and 0.290, respectively) or clinical relevant results (standardized effect sizes of 0.061 and 0.179, respectively). The predicting quality was also very low (AUC=0.508 and 0.545 respectively).

CONCLUSIONS

Fetal volume measurements in the first trimester of pregnancy are not useful as a prognostic tool for predicting pregnancies of high risk for preterm birth or a low birth weight.

Reproducibility of fetal renal pelvis volume assessed by three-dimensional ultrasonography with two different measurement techniques

PURPOSE

To evaluate reproducibility of fetal renal pelvis volume as assessed by the Virtual Organ Computer Aided AnaLysis (VOCAL) imaging program and by Automatic Volume Calculation (SonoAVC). In addition, the intra- and interobserver reliability of fetal renal pelvis volume measurements with SonoAVC were established.

METHODS

In this study, the fetal renal pelvis volume was measured using 3D ultrasonography in 76 kidneys of 66 fetuses with renal pelvis dilatation in the second or third trimester of pregnancy. After volume acquisition by one observer, the reproducibility of volume calculation was assessed using VOCAL imaging program and SonoAVC by two observers. Intra- and interobserver reproducibility was evaluated by calculating intraclass correlation coefficients (ICC), coefficient of variation (CV) and repeatability coefficient (r). Bland-Altman plots were generated to explore agreement.

RESULTS

A high degree of reproducibility was observed between VOCAL and SonoAVC, ICC of 0.989; 95% CI 0.983-0.993, respectively. Intraobserver reproducibility of volume measurements performed by SonoAVC demonstrated a high degree of reliability with ICC of 0.995 (95% CI 0.993-0.997), CV 6.05% and r of 0.75. The interobserver reproducibility with ICC of 0.995 (95% CI 0.992-0.997), CV 10.14% and r 1.21 was also indicative of good reliability.

CONCLUSION

Volume measurements of fetal renal pelvis performed by SonoAVC renders reproducible measurements in comparison with the VOCAL imaging program. There is no significant difference between VOCAL imaging program and SonoAVC. The intra- and interobserver reliability of the fetal renal pelvis measurements made by SonoAVC were considered to be very good. SonoAVC, however, needs post processing in the majority of cases but is less time consuming than VOCAL.

Appropriate cone dimensions to achieve negative excision margins after large loop excision of transformation zone in the uterine cervix for cervical intraepithelial neoplasia

AIMS

To determine appropriate cone dimensions for predicting margin status after large loop excision of transformation zone (LLETZ) treatment.

METHODS

An observational study performed at the Colposcopy Unit of a university hospital setting involving patients who underwent LLETZ conisation within a 1-year period. Data concerning the characteristics, cone dimensions, lesion grade and excision margins of the patients were recorded.

RESULTS

The median age of the women (n = 61) was 38 years (18-53). LLETZ cone specimens had 36.1% of cervical intraepithelial neoplasia (CIN)2/3 lesion and 13.1% positive margins. Mean cone depth and volume were 10.9 mm and 2.3 cm(3), respectively. Multiple logistic regression for main predictors and after adjustment for age, parity and CIN severity showed that cone volume and length, cone base surface and proportion of excised volume had a significant effect on margin positivity. ROC analysis showed that optimal cut-off for cone volume was 2.1 cm(3) (87.5% sensitivity - 54.7% specificity) or 8.6% of initial cervical volume (75% sensitivity - 75.5% specificity), and for cone length it was 10 mm (100% sensitivity - 52.8% specificity). Optimal cut-off for cone base surface as percentage of ectocervical surface was 32.7% (75% sensitivity - 69.8% specificity).

CONCLUSIONS

These findings should be taken into consideration when planning the outer boundaries of excision and cervical tissue to be removed so as to achieve oncologically safe limits.

Assessment of renal volume by three-dimensional ultrasonography in pregnant bitches: an experimental study using virtual organ computer-aided analysis

Background

To assess and to compare the renal volume evolution in bitches during pregnancy by two-dimensional (2D) ultrasonography using the ellipsoid technique (volume = length x width x depth x 0.523) and three-dimensional (3D) ultrasonography using the Virtual Organ Computer-aided AnaLysis (VOCAL) method. A longitudinal prospective study was performed with 17 normal Golden Retrievers bitches during pregnancy from heat to the last third of gestation. The ultrasound scans were performed by two veterinarians. The left and right kidneys were assessed in three moments (day 0 = non-pregnant bitches; days 1^st to 20^th of pregnancy and days 21^st to 40^th of pregnancy) by three techniques (ellipsoid; VOCAL 12° and VOCAL 30°). For reproducibility calculations, we used the intraclass correlation coefficient (ICC).

Results

The inferential result of the volumes in ANOVA revealed the interaction effect between side and moment (p = 0.009). The 3D techniques showed, in average, the same renal volumes (p = 0.137) regardless of the side and moment. Considering the right side, the renal volume in the day 0 was smaller than the day 21^st to 40^th (p = 0.029). Considering the left side, the renal volume at day 0 was smaller than the day 1^st to 20^th (p = 0.020) and day 21^st to 40^th (p = 0.007). It was found good intra observer reproducibility (ICC > 0.9) and none of the three techniques showed a good inter observer reproducibility (ICC < 0.7).

Conclusion

The renal volume bitches by 3D ultrasonography using the VOCAL method (12° and 30°) had good correlation with the volume obtained by 2D ultrasonography method.

Fetal volume measurements with three dimensional ultrasound in the first trimester of pregnancy, related to pregnancy outcome, a prospective cohort study

Background

First trimester growth restriction is associated with an increased risk of adverse birth outcomes (preterm birth, low birth weight and small for gestational age at birth). The differences between normal and abnormal growth in early pregnancy are small if the fetal size is measured by the crown-rump-length. Three-dimensional ultrasound volume measurements might give more information about fetal development than two-dimensional ultrasound measurements. Detection of the fetus with a small fetal volume might result in earlier detection of high risk pregnancies and a better selection of high risk pregnancies.

Methods

A prospective cohort study, performed at the Máxima Medical Centre, in Eindhoven-Veldhoven, the Netherlands. During the routine first trimester scan with nuchal translucency measurement 500 fetal volumes will be obtained. The gestational age is based on the first day of the last menstrual period in a regular menstrual cycle and by the crown-rump-length. The acquired datasets are collected and stored on a hard disk for offline processing and volume calculation. The investigator who performs the volume measurements is blinded for the results of the first trimester scan. The manual mode will be used to outline the Region Of Interest, the fetal head and rump, in all cross sections. The fetal volumes are calculated with a rotational step of 9°.

First, the relation between fetal volume and gestational age, for a set of participants with normal pregnancies (training set), will be assessed. This model will then be used to determine expected values of fetal volume for a normal pregnancy, which will be referred to as expected normal values. Secondly, for a new set of participants with normal pregnancies and a set of participants with complicated pregnancies (together defined as validation set), the observed fetal volumes (FV_observed) are compared with their expected normal values (FV_expected) and expressed as a percentage of the expected normal value. The mean difference in percentage error between the set of normal versus complicated pregnancies will then be compared using the independent-samples t-test. Finally, logistic regression analysis will be applied to the validation set of participants to analyze the possibility of predicting the pregnancy outcome after fetal volume calculation in the first trimester, using this percentage error.

Discussion

After this study it is clear whether FV measurement in the first trimester can detect high risk pregnancies. If it is possible to detect these pregnancies, more intensive follow up in these pregnancies might result in fewer complicated pregnancies and fewer fetal morbidities.

A new semi-automated method for fetal volume measurements with three-dimensional ultrasound: preliminary results

OBJECTIVE

Complications in pregnancy are suggested to be the result of intrauterine conditions in the first trimester of pregnancy. Three-dimensional ultrasound volume measurements might give more information, compared with two-dimensional measurements. Commonly available methods for volume measurements are not suited for daily practice. This is a report of preliminary results of a promising, more practical semi-automated method for volume calculations with three-dimensional ultrasound.

METHOD

Volume datasets of 16 objects (10.2-41.5 cm(3) ) were obtained. Euclidean shortening flow and Perona and Malik were used as image enhancement techniques. The image gradient was calculated. The points of interest were detected by the iso-intensity and the edge-detection technique. Volume measurements with Volume Computer-aided AnaLysis (VOCAL) are used as a reference. A volume dataset of a first trimester fetus was acquired to test this method in vivo.

RESULTS

The mathematical calculations with iso-intensity (Perona and Malik: average= -1.57 cm(3) , SD=4.05; and Euclidean shortening flow: average= -1.38 cm(3) , SD=2.47) showed results comparable with the VOCAL method (average= +1.28 cm(3) , SD=2.07). We also succeeded in detecting all voxels in the whole contour of a 12-week fetus.

CONCLUSION

Mathematical volume calculations are possible with the semi-automated method. We were able to apply this new method on a first trimester fetus. This new method is promising for future use in the daily practice.

Evaluation of two-dimensional and three-dimensional ultrasound in the assessment of thyroid volume of the Indo-Pacific bottlenose dolphin (Tursiops aduncus)

The assessment of thyroid volume plays an indispensable role in the diagnosis and management of different thyroid diseases. The present study evaluates the accuracy of dolphin thyroid volume measurement as determined by four two-dimensional (2D) ultrasound methods (A-D), with a standard of reference using three-dimensional (3D) ultrasound. The measurement accuracy for different recognized thyroid configuration is also evaluated. Inter- and intraoperator variability of the measurement methods was determined. Thyroid ultrasound examinations were conducted in 16 apparently healthy Indo-Pacific bottlenose dolphins (Tursiops aduncus) with 2D and 3D ultrasound under identical scanning conditions. All 2D ultrasound measurement methods yielded high accuracies (79.9-81.3%) when compared with the 3D ultrasound measurement, and had high measurement reproducibility (77.6-86.2%) and repeatability (78.1-99.7%). For 2D ultrasound measurements, Methods A and B were more accurate and reliable than Methods C and D, regardless of thyroid configuration. Ultrasound is useful in the measurement of thyroid volume in bottlenose dolphins. For the first time, a reliable ultrasound scanning protocol for measuring dolphin thyroid volume was developed, which provides a means to establish a normative reference for the diagnosis of thyroid pathologies and to monitor the thyroid volume during the course of treatment in living dolphins. Key words: 3D ultrasound, Indo-Pacific bottlenose dolphin, thyroid volume measurement, Tursiops aduncus.

Reference intervals for fetal heart volume from 3-dimensional sonography using the extended imaging virtual organ computer-aided analysis method at gestational ages of 20 to 34 weeks

OBJECTIVES

The purpose of this study was to establish the reference range for fetal heart volume from 3-dimensional (3D) sonography using the extended imaging virtual organ computer-aided analysis method.

METHODS

The fetal heart volume was measured in 303 normal singleton pregnancies at gestational ages of 20 to 34 weeks using 3D sonography. The extended imaging virtual organ computer-aided analysis method was used to obtain a sequence of 10 parallel symmetric sections through the heart, according to examiner-determined limits (the apex at one extremity and the connection to the great vessels at the other). Heart contours were drawn manually in all sections to obtain the 3D volume measurement, which was provided automatically by the software. Normal z scores and percentile reference ranges for each gestational age were constructed.

RESULTS

The fetal heart volume increased with gestational age. The mean values were 3.09 mL at 20 weeks, 9.18 mL at 26 weeks, and 24.89 mL at 34 weeks, according to the following formulas: fetal heart volume (mL) = 18.0076 - 2.1005 × gestational age + 0.0677 × gestational age2 (R(2) = 0.922); and SD (mL) = (4.5038 - 0.4281 × gestational age + 0.0114 × gestational age2) × √1.495808 (R(2) = 0.922).

CONCLUSIONS

A reference range for fetal heart volume using the 3D sonographic extended imaging virtual organ computer-aided analysis method at gestational ages of 20 to 34 weeks was established.

Preoperative assessment of endometrial carcinoma by three-dimensional power Doppler angiography

OBJECTIVE

Preoperative evaluation of the depth of myometrial invasion in endometrial carcinoma is challenging. The objective of this study was to evaluate the usefulness of three-dimensional power Doppler angiography (3D-PDA) in this setting.

METHODS

Sonographic and histological data on 100 consecutive cases of endometrial carcinoma were analyzed. The endometrial and myometrial vascular indices VI (vascularization index), FI (flow index) and VFI (vascularization flow index) were calculated by 3D-PDA. The results were compared with a complete surgical staging.

RESULTS

The mean ( ± SD) age of patients was 67.1 ± 8.8 (range, 33-87) years. Forty-six patients had deep (≥ 50%) myometrial invasion. Eight patients had metastases, seven of them with deep invasion. Three patients were found to have carcinomas of non-uterine origin on histology, and these were excluded from further statistical analysis. The median endometrial and myometrial vascular indices were higher in the group with deep invasion than in the group without. Following multivariable analysis of the indices only the endometrial FI was independently associated with deep invasion (OR, 1.061; 95% CI, 1.023-1.099; P = 0.001). However, a greater endometrial volume was also an independent predictor of deep invasion (OR, 1.109; 95% CI, 1.011-1.215; P = 0.028).

CONCLUSION

Our study suggests that endometrial and, to a lesser degree, myometrial vascular indices and endometrial volume correlate with the depth of myometrial invasion in endometrial carcinoma.

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

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

Assessment of lung volume by 3-dimensional sonography and magnetic resonance imaging in fetuses with congenital diaphragmatic hernias

OBJECTIVES

The purpose of this study was to evaluate the influence of different rotation angles in assessment of the contralateral lung volume by 3-dimensional (3D) sonography in comparison to magnetic resonance imaging (MRI) in fetuses with congenital diaphragmatic hernias.

METHODS

A total of 126 measurements by 3D sonography and MRI were conducted in 81 patients between 18 and 39 weeks' gestation. The 3D sonographic volumes of the contralateral fetal lung were calculated by the rotational technique (virtual organ computer-aided analysis) with rotation angles of 6°, 15°, and 30°. Transverse multiplanar T2-weighted MRI was performed for the MRI measurements. To compare the accuracy of 3D sonographic volumetry using different rotation angles, MRI assessment was taken as the reference method, and percentage errors and limits of agreement were calculated for each angle.

RESULTS

Three-dimensional sonographic volume measurements showed a high correlation with MRI (6° angle, R(2) = 0.86; 15° angle, R(2) = 0.78; 30° angle, R(2) = 0.68). The mean percentage error showed no systematic error. With regard to random error, the 6° step had significantly lower values than the larger angles 30° step (R = 0.472) and the narrowest limits of agreement.

CONCLUSIONS

Especially when using a small rotation angle, assessment of the contralateral fetal lung volume by 3D sonography in congenital diaphragmatic hernias is a reliable alternative to MRI.

Embryo volume measurement: an intraobserver, intermethod comparative study of semiautomated and manual three-dimensional ultrasound techniques

OBJECTIVE

To compare the reliability of our recently introduced technique for first-trimester embryo volume measurement, the 'semiautomated technique' using both Virtual Organ Computer-aided AnaLysis (VOCAL(™) ) and Sonography-based Automated Volume Count (SonoAVC) with a manual technique using VOCAL alone.

METHODS

Seventy-four subjects with viable, singleton first-trimester in-vitro fertilization (IVF) pregnancies were recruited. Each subject underwent transvaginal sonography, at which a three-dimensional ultrasound dataset of the entire gestational sac was acquired. Each embryo volume was measured by two techniques, each performed twice. In the semiautomated technique VOCAL was used to calculate the volume of the gestational and yolk sacs, and SonoAVC was used to quantify the fluid volume within the amniotic and extra-amniotic cavities. Embryo volume was calculated by subtracting the sum of yolk sac, amniotic and extra-amniotic fluid volumes from gestational sac volume. In the manual technique, VOCAL was used to delineate the entire embryo using 9° rotations. Reliability was assessed using limits of agreement and intraclass correlation coefficient.

RESULTS

Datasets were included from 52 eligible subjects. Median gestational age was 7 + 4 weeks; median crown-rump length (CRL) was 13 (range, 2-29) mm; and median embryo volume was 1.8 (range, 0.03-8.1) cm(3) using the semiautomated technique and 0.7 (range 0.009-3.6) cm(3) using the manual technique. There was a significant discrepancy in the volumes measured by the two different techniques. Assessment of the limits of agreement suggested that the semiautomated technique (-15.8% to 14.0% of the mean embryo volume) was more reliable than was the manual technique (-22.4% to 26.6%).

CONCLUSION

The semiautomated technique is more reliable than is the manual technique for embryo volume measurement. However, the discrepancy in measurements between the two methods raises concerns over the validity of the semiautomated technique that require further investigation.

Surface area measurement using rendered three-dimensional ultrasound imaging: an in-vitro phantom study

OBJECTIVE

Cranial sutures and fontanelles can be reliably demonstrated using three-dimensional (3D) ultrasound with rendering. Our objective was to assess the repeatability and validity of fontanelle surface area measurement on rendered 3D images.

METHODS

This was an in-vitro phantom validation study. Four holes, representing fontanelles, were cut on a flat vinyl tile. The phantom was scanned in a test-tank by two sonographers, at four different depths and using two different 3D sweep directions. The surface areas were measured on scan images and also directly from the phantom for comparison. Coefficients of variation (CVs), intraclass correlation coefficients (ICCs) and Bland-Altman plots were used for repeatability analysis. Validity was expressed as the percentage difference of the measured area from the true surface area.

RESULTS

Validity of measurement was satisfactory with a mean percentage difference of - 5.9% (median = - 3.5%). The 95% limits of agreement were - 23.9 to 12.1%, suggesting that random error is introduced during image generation and measurement. Repeatability of caliper placement on the same image was higher (intraobserver CV = 1.6%, ICC = 0.999) than for measurement of a newly generated scan image (intraobserver CV = 5.5%, ICC = 0.992). Reduced accuracy was noted for the smallest shape tested.

CONCLUSION

Surface area measurements on rendered 3D ultrasound images are accurate and reproducible in vitro.

Inter- and intra-observer variation of fetal volume measurements with three-dimensional ultrasound in the first trimester of pregnancy

OBJECTIVES

To determine the inter- and intra-observer variation of volume calculations of human fetuses at a gestational age of 11(+0)-13(+6) weeks by three-dimensional ultrasound (3DUS).

METHODS

3DUS datasets were acquired during nuchal translucency measurements. The fetal volume (FV) was measured in 65 cases by two independent investigators. The Virtual Organ Computer aided AnaLysis (VOCAL™) imaging software was used to manually calculate the FV (rotational angle 9°). Inter- and intra-observer variation were assessed by Bland-Altman plots and intraclass correlation coefficients (ICC).

RESULTS

Both inter- and intraobserver reproducibility were highly reliable as shown by the Bland-Altman plots and an ICC of respectively 0.934 and 0.994.

CONCLUSION

FV calculation by 3DUS with VOCAL and a rotational angle of 9° is feasible and has a high inter- and intraobserver reliability in the first trimester of pregnancy.

In vitro models of the fetal lung: comparison of lung volume measurements with 3-dimensional sonography and magnetic resonance imaging

OBJECTIVES

Three-dimensional (3D) sonography is an established volumetric method in gynecology and obstetrics. The aim of this study was to investigate the variability of 3D sonographic measurements and their accuracy in comparison with magnetic resonance imaging (MRI) for assessing fetal lung volume using in vitro lung models.

METHODS

Twenty-three in vitro lung models with randomly defined volumes ranging from 1 to 60 mL were made from gelatin with plastic sheaths, manually molded into the shape of fetal lungs. The models were measured using 3D sonography and MRI. The 3D sonographic volumes were calculated using the rotational technique with angles of 6° and 30°. Multiplanar T2-weighted sequences were used for the MRI measurements. The percentage error and absolute percentage error were calculated for each method, and intraobserver and interobserver variability in 3D sonographic measurements was assessed with intraclass correlation coefficients (ICCs). Agreement between calculated and real volumes using the limits of agreement method was also evaluated.

RESULTS

The ICCs for the rotation angles indicated very good intraobserver and interobserver variability (6°, 0.995 and 0.996; 30°, 0.997 and 0.985). No systematic errors were observed in the mean percentage errors for 3D sonographic measurements or MRI volumetry. The lowest median absolute percentage error (1.76) was obtained with MRI volumetry, significantly lower than the values for sonography (6°, 5.00; P < .001; 30°, 5.49; P < .001). There were no significant differences in absolute percentage errors between the rotation angles (P = .82) and no significant differences in limits of agreement between 3D sonography and MRI (6°, P = .76; 30°, P = .39).

CONCLUSIONS

Three-dimensional sonographic volumetry was almost as accurate as MRI in this in vitro model and can be regarded as a good alternative method. Further research is needed to confirm these findings in vivo and to assess the prognostic value in fetuses with lung hypoplasia (eg, congenital diaphragmatic hernias).

A standardized measurement technique may improve the reliability of measurements of endometrial thickness and volume

OBJECTIVE

To investigate whether standardization of the multiplanar view (SMV) when evaluating the uterus using three-dimensional ultrasonography (3D-US) improves intra- and interobserver reliability and agreement with regard to endometrial measurement.

METHODS

Two-dimensional (2D) and 3D-US was used to measure endometrial thickness by two observers in 30 women undergoing assisted reproduction treatment. Endometrial volume was measured with Virtual Organ Computer-aided AnaLysis (VOCAL(™)) in the longitudinal (A) and coronal (C) planes using an unmodified multiplanar view (UMV) and a standardized multiplanar view (SMV). Measurement reliability was evaluated by intraclass correlation coefficient (ICC) and agreement was examined using Bland-Altman plots with limits of agreement (LoA). The ease of outlining the endometrial-myometrial interface was compared between the A- and C-planes using subjective assessment.

RESULTS

Endometrial volume measurements using the SMV and A-plane were more reliable (intra- and interobserver ICCs, 0.979 and 0.975, respectively) than were measurements of endometrial thickness using 2D-US (intra- and interobserver ICCs, 0.742 and 0.702, respectively) or 3D-US (intra- and interobserver ICCs, 0.890 and 0.784, respectively). The LoAs were narrower for SMV than for UMV. Reliability and agreement were not much different between the A- and C-planes. However the observers agreed that delineating the endometrial-myometrial interface using the A-plane was easier (first and second observer, 50.0 and 46.7%, respectively) or 'comparable' (50 and 53.3%, respectively), but never more difficult than using the C-plane.

CONCLUSIONS

Endometrial volume measurements are more reliable than endometrial thickness measurements and are best performed using SMV and the A-plane.

Sonographic measurement of cervical volume in nonpregnant women using the geometric formula for a cylinder versus the three-dimensional automated virtual organ computer-aided analysis (vocal)

BACKGROUND

To sonographically evaluate the volume of uterine cervix in nonpregnant women with use of the geometric formula for a cylinder and to assess agreement with the reference Virtual Organ Computer-Aided AnaLysis (VOCAL) method.

METHODS

Three-dimensional ultrasound volume datasets of the uterine cervix from 81 women were obtained prospectively within a 1-year period. Volume measurements were performed using VOCAL and the geometric formula for a cylinder. Reliability was evaluated using intraclass correlation coefficient and Bland-Altman plots were produced to examine intermethod agreement. Time needed to perform measurements was compared with Student's t test.

RESULTS

There was good agreement between VOCAL and the geometric formula for a cylinder (mean percentage difference, -0.78%; 95% limits of agreement, -17.59-16.03%). Measurements made by the formula for a cylinder were slightly greater than VOCAL by a mean (±SE) of 0.78% (±0.95%). A high degree of reliability was observed between the two methods (intraclass correlation coefficient, 0.97; 95%CI, 0.95-0.98). Cervical volume estimation with the geometric formula for a cylinder was faster to obtain.

CONCLUSIONS

This method comparison study shows that the geometric formula for a cylinder has good agreement with VOCAL and can determine the volume of the cervix in a faster way.

Letrozole and norethisterone acetate versus letrozole and triptorelin in the treatment of endometriosis related pain symptoms: a randomized controlled trial

BACKGROUND

When aromatase inhibitors are used to treat premenopausal women with endometriosis, additional drugs should be used to effectively down-regulate gonadal estrogen biosynthesis. This randomized prospective open-label study compared the efficacy in treating pain symptoms and the tolerability of letrozole combined with either norethisterone acetate or triptorelin.

METHODS

Women with pain symptoms caused by rectovaginal endometriosis were treated with letrozole (2.5 mg/day) and were randomized to also receive either oral norethisterone acetate (2.5 mg/day; group N) or intramuscular injection of triptorelin (11.25 mg every 3 months; group T). The scheduled length of treatment was 6 months. A visual analogue scale and a multidimensional categorical rating scale were used to assess the severity of pain symptoms. The volume of the endometriotic nodules was estimated by ultrasonography using virtual organ computer-aided analysis. Adverse effects of treatment were recorded.

RESULTS

A total of 35 women were randomized between the two treatment protocols. Significantly more patients in group N rated their treatment as satisfactory or very satisfactory (64.7%) as compared to group T (22.2%; p=0.028). The intensity of both non-menstrual pelvic pain and deep dyspareunia significantly decreased during treatment in both study groups, though no statistically meaningful difference between the two groups was apparent. Reduction in the volume of endometriotic nodules was significantly greater in group T than in group N. Interruption of treatment due to adverse effects significantly differed between the groups, with 8 women in group T (44.4%) and 1 woman in group N (5.9%) interrupting treatment (p=0.018). Similarly, 14 women included in group T (77.8%) and 6 women included in group N (35.3%) experienced adverse effects of treatment (p=0.018). During treatment, mineral bone density significantly decreased in group T but not in group N.

CONCLUSIONS

Aromatase inhibitors reduce the intensity of endometriosis-related pain symptoms. Combining letrozole with oral norethisterone acetate was associated with a lower incidence of adverse effects and a lower discontinuation rate than combining letrozole with triptorelin.

Influence of different rotation angles in assessment of lung volumes by 3-dimensional sonography in comparison to magnetic resonance imaging in healthy fetuses

OBJECTIVES

Three-dimensional (3D) sonographic volumetry is established in gynecology and obstetrics. Assessment of the fetal lung volume by magnetic resonance imaging (MRI) in congenital diaphragmatic hernias has become a routine examination. In vitro studies have shown a good correlation between 3D sonographic measurements and MRI. The aim of this study was to compare the lung volumes of healthy fetuses assessed by 3D sonography to MRI measurements and to investigate the impact of different rotation angles.

METHODS

A total of 126 fetuses between 20 and 40 weeks' gestation were measured by 3D sonography, and 27 of them were also assessed by MRI. The sonographic volumes were calculated by the rotational technique (virtual organ computer-aided analysis) with rotation angles of 6° and 30°. To evaluate the accuracy of 3D sonographic volumetry, percentage error and absolute percentage error values were calculated using MRI volumes as reference points. Formulas to calculate total, right, and left fetal lung volumes according to gestational age and biometric parameters were derived by stepwise regression analysis.

RESULTS

Three-dimensional sonographic volumetry showed a high correlation compared to MRI (6° angle, R(2) = 0.971; 30° angle, R(2) = 0.917) with no systematic error for the 6° angle. Moreover, using the 6° rotation angle, the median absolute percentage error was significantly lower compared to the 30° angle (P < .001). The new formulas to calculate total lung volume in healthy fetuses only included gestational age and no biometric parameters (R(2) = 0.853).

CONCLUSIONS

Three-dimensional sonographic volumetry of lung volumes in healthy fetuses showed a good correlation with MRI. We recommend using an angle of 6° because it assessed the lung volume more accurately. The specifically designed equations help estimate lung volumes in healthy fetuses.

Assessment of postoperative postvoid residual bladder volume using three-dimensional ultrasound volumetry

The aim of our prospective study was to assess the concordance between postvoid residual volumes (PVR) of the urinary bladder obtained by two different three-dimensional (3-D) ultrasound (US) volumetric methods (VOCAL and XI VOCAL) and with measurement by the catheter in postoperative patients who have undergone radical hysterectomy. The 3-D sonographic volume-determination of PVR with both methods correlated significantly with the actual amount of PVR by the catheter. The accuracy of both 3-D US volumetric methods was significantly higher under 300 mL of PVR. Bland-Altman plots were generated to examine limits of agreement. Both noninvasive 3-D sonographic methods are appropriate for the correct volume-determination of PVR following radical hysterectomy. Thus, we may avoid routine, albeit often unnecessary, catheterization to measure postoperative residual bladder volumes and subsequently the incidence of lower urinary tract infection may be reduced and better postoperative comfort for patients may be permitted.

[Ovarian stimulation monitoring: past, present and perspectives]

Since the inception of Assisted Reproductive Technology (ART), knowing the moment of ovulation has always been a priority. Initially, the monitoring was accomplished by observing the luteinizing hormone (LH) surge just before ovulation. Currently, in all ART facilities, the monitoring of all stimulated ovulatory cycles is done by using the conventional two-dimensional (2D) ultrasound to measure follicle diameter and by drawing blood tests that measure estradiol, progesterone, and luteinizing hormone levels. These exams allow determination of the numbers and quality of growing ovarian follicles and evaluation of follicle maturity before choosing the appropriate time for ovulation triggering. The monitoring of ovulatory cycles has now become enhanced with the arrival of new software called SonoAVC. This software allows the utilization of 3D blocks to immediately calculate the total number and volume of the follicles inside the ovary. This automatic approach is faster, precise, and more efficient. It also has better reproducibility than the classical 2D diameters. Furthermore, certain ART professionals envision that by using the SonoVac technology, patients will no longer need to be monitored with regular ultrasounds and with systematic hormonal testing.

Reliability and validity of splenic volume measurement by 3-D ultrasound

AIM

  We prospectively evaluated the reliability and validity of splenic volume with 3-D ultrasound measurement and clarified its clinical usefulness.

METHODS

  Thirty healthy volunteers and 30 patients with cirrhosis were included in this study. All 3-D ultrasound examinations of splenic volumes were performed twice by two experienced sonographers with transabdominal ultrasound using virtual organ computer-aided analysis (VOCAL). Reliability was confirmed among all subjects by evaluating within-observer repeatability and between-observer reproducibility using intraclass correlation coefficients (ICC) and Bland-Altman plots. Overall between-instrument agreement of the measurements and computed tomography (CT) volumetry among cirrhotic patients were performed to determine validity.

RESULTS

  For all 240 examinations, 3-D ultrasound visualization and measurement of the spleen volume was possible. Mean spleen volume was 104.0 mL for the volunteers and 283.5 mL for the cirrhotic patients. The repeatability was high, with ICC (95% confidence interval) of 0.996 (0.993-0.997) for observer A and 0.997 (0.994-0.998) for observer B. Moreover, the interobserver ICC was 0.996, indicating high reproducibility. Despite the difference in volume between the volunteers and cirrhotic patients, sensitivity analyses indicated consistent results for both groups. Regarding the validity of the 3-D ultrasound measurement, it also showed moderate to high agreement with CT volumetry, with mean ICC of 0.922 and 0.924 for observers A and B, respectively. The reliability and validity results from the Bland-Altman plots were similar to those from the ICC, with limits of agreement consistently narrow from a clinically practical view.

CONCLUSION

  3-D ultrasound measurements using VOCAL are valid and reliable in spleen volume examinations.

Reliability of fetal cardiac volumetry using spatiotemporal image correlation: assessment of in-vivo and in-vitro measurements

OBJECTIVE

To assess the reliability of measurement of fetal cardiac ventricular volume, stroke volume, and ejection fraction with four-dimensional ultrasound using spatiotemporal image correlation (STIC).

METHODS

Volume datasets were collected from two sources: 24 from fetuses over a range of gestational ages and 12 from a miniature balloon model. Datasets were analyzed by three observers, repeatedly in 12 fetal datasets and all balloon datasets. Volume calculations were obtained by manually tracing multiple parallel slices (three-dimensional (3D) slice method). Measurement error was assessed by calculating standard errors of measurement (SEM) and coefficients of variation (CV). Reliability was assessed by calculating interobserver and intraobserver intraclass correlation coefficients (ICC).

RESULTS

Measurement errors of balloon volumes were small and reliability was good (SEM <or= 0.07 mL, ICC 0.98-1.00). Fetal ventricle volume measurement error ranged from 0.09 to 0.20 mL and CV from 14.6 to 28.3%. Ventricular volume reliabilities for intra- and interobserver comparisons were greater than or equal to 0.94 and 0.75, respectively. Fetal stroke volume measurement error (SEM 0.17 mL), CV (21.9%) and reliability were measured (intraobserver ICC: left ventricle stroke volume (LVSV), 0.93 vs. right ventricle stroke volume (RVSV), 0.88; interobserver ICC: LVSV, 0.75 vs. RVSV, 0.86). The measurement error decreased with increasing operator experience. The reliability of ejection fraction calculations was poor (ICC < 0.7) for intra- and interobserver comparisons.

CONCLUSIONS

Volume measurements obtained with STIC and 3D slice methods using a balloon model were reliable. In the fetus, measurement errors decreased with increasing operator experience, and reliability was better for stroke volume than for ejection fraction.

Comparison of inter- and intraobserver agreement and reliability between three different types of placental volume measurement technique (XI VOCAL, VOCAL and multiplanar) and validity in the in-vitro setting

OBJECTIVES

To compare XI VOCAL (eXtended Imaging Virtual Organ Computer-aided AnaLysis) for three-dimensional (3D) ultrasound volumetry of the placenta and of phantom objects with a rotational method using VOCAL and with the multiplanar method.

METHODS

We acquired 3D volume datasets from 32 fetuses at 11-14 weeks' gestation. Placental volume was calculated twice by each of two observers using XI VOCAL (with 5, 10, 15 and 20 slices), multiplanar (1-mm interval) and VOCAL (with 12 degrees, 18 degrees and 30 degrees rotation) methods. In addition, validity was assessed using the in-vitro setting with three phantom objects of known volume.

RESULTS

Both inter- and intraobserver reliabilities were very high for all three methods. There was no systematic bias between any two methods except between XI VOCAL (10 slices) and the multiplanar (1-mm interval) method, with a smaller volume using the former method. The limits of agreement were wide between any two of the three methods. In the in-vitro setting, there was a trend towards less valid measurements with the XI VOCAL technique and fewer slices. With the same number of steps, measurements made with VOCAL (12 degrees and 18 degrees) were more valid than were those made with XI VOCAL (15 and 10 slices, respectively).

CONCLUSION

XI VOCAL cannot be used interchangeably with VOCAL or multiplanar techniques in measuring placental volume at 11-14 weeks' gestation.

An innovative virtual reality technique for automated human embryonic volume measurements

BACKGROUND

The recent introduction of virtual reality (VR) enables us to use all three dimensions in a three-dimensional (3D) image. The aim of this prospective study was to evaluate an innovative VR technique for automated 3D volume measurements of the human embryo and yolk sac in first trimester pregnancies.

METHODS

We analysed 180 3D first trimester ultrasound scans of 42 pregnancies. Scans were transferred to an I-Space VR system and visualized as 3D 'holograms' with the V-Scope volume-rendering software. A semi-automatic segmentation algorithm was used to calculate the volumes. The logarithmically transformed outcomes were analysed using repeated measurements ANOVA. Interobserver and intraobserver agreement was established by calculating intraclass correlation coefficients (ICCs).

RESULTS

Eighty-eight embryonic volumes (EVs) and 118 yolk sac volumes (YSVs) were selected and measured between 5(+5) and 12(+6) weeks of gestational age (GA). EV ranged from 14 to 29 877 mm(3) and YSV ranged from 33 to 424 mm(3). ANOVA calculations showed that when the crown-rump length (CRL) doubles, the mean EV increases 6.5-fold and when the GA doubles, the mean EV increases 500-fold (P < 0.001). Furthermore, it was found that a doubling in GA results in a 3.8-fold increase of the YSV and when the CRL doubles, the YSV increases 1.5-fold (P < 0.001). Interobserver and intraobserver agreement were both excellent with ICCs of 0.99.

CONCLUSION

We measured the human EV and YSV in early pregnancy using a VR system. This innovative technique allows us to obtain unique information about the size of the embryo using all dimensions, which may be used to differentiate between normal and abnormal human development.

Reprodutibilidade interobservador dos índices vasculares do Doppler de amplitude tridimensional do embrião entre 7 e 10 semanas e 6 dias de gestação

OBJETIVO: Avaliar a reprodutibilidade interobservador dos índices de vascularização do Doppler de amplitude tridimensional (Doppler de amplitude 3D) no primeiro trimestre de gestação. MATERIAIS E MÉTODOS: Realizou-se estudo de reprodutibilidade com 32 gestantes normais entre 7 e 10 semanas e 6 dias. Para o cálculo do volume tridimensional dos embriões utilizou-se o método VOCAL (Virtual Organ Computer-aided AnaLysis) com ângulo de rotação de 12°. Em seguida obtiveram-se, automaticamente, os três índices vasculares do Doppler de amplitude 3D: índice de vascularização (VI), índice de fluxo (FI) e índice de vascularização e fluxo (VFI). Para o cálculo da variabilidade interobservador, um examinador realizou uma segunda medida dos 32 embriões e um segundo examinador realizou uma terceira medida dos mesmos volumes, ambos desconhecendo os resultados do outro. Utilizaram-se, para análise estatística, o coeficiente de correlação intraclasse (CCI) e gráficos de Bland-Altman. RESULTADOS: Observou-se boa reprodutibilidade interobservador dos três índices vasculares. O VI apresentou CCI = 0,9 e média da diferença = -1,1; o FI apresentou CCI = 0,9 e média da diferença = -0,5; e o VFI apresentou CCI = 0,9 e média da diferença = -1,1. CONCLUSÃO: Os índices vasculares do Doppler de amplitude 3D do embrião no primeiro trimestre de gestação foram altamente reprodutíveis, em especial o FI.

Reproducibility of fetal heart volume by 3D-sonography using the XI VOCAL method

Background

To assess the reliability of fetal heart volume measurement by three-dimensional sonography (3DUS) using the eXtended Imaging Virtual Organ Computer-aided AnaLysis (XI VOCAL) method.

Methods

This reliability study enrolled 30 pregnant women with singleton healthy pregnancies between 19 and 34 weeks of gestation. All volume acquirements were performed with a convex volumetric transducer (C3-7ED) coupled to an Accuvix XQ sonography device (Medison, Korea). The XI VOCAL 10 planes was the method of choice for volumetric measurement. 3D datasets were analyzed by two observers (EQSB and HJFM); fetal heart volume was measured twice by the first and once by the second observer to calculate intra and interobserver reproducibility. Statistical analysis used pareated Student's t test (p) and calculated Intraclass correlation coefficients (ICC). Bland-Altman plots were also constructed.

Results

We observed an excellent intra- and interobserver reliability for fetal cardiac volume assessed by XI VOCAL. For the intraobserver the ICC was 0.998 (95% CI: 0.997; 0.999), with mean of differences of 0.12 cm³ (95% limits of agreement: -0.84; +0.84; p = 0.130). For interobserver the ICC was 0.899 (95%CI: 0.996; 0.998), mean of differences 0.05 cm³ (95% limits of agreement: -0.84; +0.84; p = 0.175).

Conclusion

Fetal cardiac volume assessed by 3DUS using XI VOCAL method is highly reproducible between 19 to 34 gestational weeks.

A novel technique for the semi-automated measurement of embryo volume: an intraobserver reliability study

The aim was to assess intraobserver reliability of a new semi-automated technique of embryo volumetry. Power calculations suggested 46 subjects with viable, singleton pregnancies were required for reliability analysis. Crown rump length (CRL) of each embryo was analyzed using 2-D and a 3-D dataset acquired using transvaginal ultrasound. Virtual organ computer-aided analysis (VOCAL) was used to calculate volume of gestation sac (GSV) and yolk sac (YSV) and SonoAVC (sonography-based automated volume count) was used to quantify fluid volume (FV). Embryo volume was calculated by subtracting FV and YSV from GSV. Each dataset was measured twice. Reliability was assessed using Bland-Altman plots and intraclass correlation coefficients (ICCs). Fifty-two datasets were analyzed. Median embryo volume was 1.8 cm(3) (0.1 to 8.1 cm(3)); median gestational age 7 + 4 weeks; median CRL 13 mm (2 to 29 mm). Mean difference of embryo volume measurements was 0.1cm(3) (limits of agreement [LOA] -0.3 to 0.4 cm(3)); multiples of mean (MoM) 0.38; mean difference of CRL measurements 0.3 mm (LOA -1.4 to 2.0 mm), MoM = 0.26. ICC for embryo volume was 0.999 (95%CI 0.998 to 0.999), confirming excellent intraobserver agreement. ICC for CRL was 0.996 (95%CI 0.991 to 0.998). Regression analysis showed good correlation between embryo volume and CRL (R(2) = 0.60). The new semi-automated 3-D technique provides reliable measures of embryo volume. Further work is required to assess the validity of this technique.

Reliability and validity of in vitro volume calculations by 3-dimensional ultrasonography using the multiplanar, virtual organ computer-aided analysis (VOCAL), and extended imaging VOCAL methods

OBJECTIVE

The purpose of this study was to assess the reliability and validity of in vitro volume calculations by 3-dimensional ultrasonography.

METHODS

This observational study was performed by 2 examiners to obtain volumes of 3 objects of different shapes and sizes filled with ultrasound gel and immersed in water. The examiners used the multiplanar (5-mm interval), virtual organ computer-aided analysis (VOCAL, 30 degrees) and extended imaging (XI) VOCAL (5, 10, 15, and 20 planes) methods to estimate the volumes of each object. A paired Student t test (P) and intraclass correlation coefficients (ICCs) were used to assess reproducibility of the methods. Validity was assessed comparing the percent differences between the estimated and the real volumes using the P value, mean differences, and ICC for each method.

RESULTS

All methods were highly reliable and valid. There were no significant differences in interobserver variability; there was a strong interobserver correlation. There were no significant differences in the percent differences between the estimated and real volumes of the objects using the 3 methods. The XI VOCAL method was superior to the multiplanar and VOCAL methods in the measurement of irregularly shaped objects. The XI VOCAL method with 10 planes estimated volumes closest to the real volumes.

CONCLUSIONS

All 3 methods were reliable and valid; however, XI VOCAL was superior to the other methods in the measurement of irregularly shaped objects.

Three-dimensional ultrasound imaging

This review is about the development of three-dimensional (3D) ultrasonic medical imaging, how it works, and where its future lies. It assumes knowledge of two-dimensional (2D) ultrasound, which is covered elsewhere in this issue. The three main ways in which 3D ultrasound may be acquired are described: the mechanically swept 3D probe, the 2D transducer array that can acquire intrinsically 3D data, and the freehand 3D ultrasound. This provides an appreciation of the constraints implicit in each of these approaches together with their strengths and weaknesses. Then some of the techniques that are used for processing the 3D data and the way this can lead to information of clinical value are discussed. A table is provided to show the range of clinical applications reported in the literature. Finally, the discussion relating to the technology and its clinical applications to explain why 3D ultrasound has been relatively slow to be adopted in routine clinics is drawn together and the issues that will govern its development in the future explored.

Fetal thigh volumetry by three-dimensional ultrasound: comparison between multiplanar and VOCAL techniques

OBJECTIVES

To evaluate the agreement between multiplanar and Virtual Organ Computer-aided AnaLysis (VOCAL()) techniques for the measurement of total fetal thigh volume and to assess the repeatability and reproducibility of measurements performed using these methods; to derive birth weight-predicting models for both methods and to compare their accuracies.

METHODS

This was a cross-sectional study of 150 singleton pregnancies at 30-42 weeks of gestation in which ultrasound volumes of the fetal thigh were obtained within 48 hours of delivery and measured using multiplanar and VOCAL techniques. Bland-Altman analyses were performed to determine the agreement between the two methods, and to evaluate intraobserver and interobserver variability in a subset of 40 patients. Birth weight-predicting models were derived using total fetal thigh volumes obtained using the VOCAL (ThiV) and multiplanar (ThiM) methods as independent variables. The accuracies of these formulas were compared.

RESULTS

The mean percentage difference between measurements performed using the VOCAL technique and the multiplanar technique was -0.04 and the 95% limits of agreement were -8.17 and 8.09. The mean percentage difference and 95% limits of agreement between paired measurements in the assessment of intraobserver and interobserver variability were -1.10 (-7.67 to 5.47) and 0.61 (-7.68 to 8.91) for the VOCAL technique and 1.03 (-6.35 to 8.41) and -0.68 (-11.42 to 10.06) for the multiplanar method, respectively. The best-fit formulas for predicting birth weight (BW) were: BW = 1025.383 + 12.775x ThiV; and BW = 1033.286 + 12.733x ThiM. There was no significant difference between the accuracies of these formulas.

CONCLUSIONS

There is good agreement between the VOCAL and multiplanar techniques for assessment of total fetal thigh volume. Measurements performed using both methods are repeatable and reproducible. For prediction of birth weight, the formulas generated in this study can be used interchangeably.

Fetal lung volume in fetuses with urinary tract malformations: comparison by 2D-, 3D-sonography and magnetic resonance imaging

OBJECTIVE

To evaluate the concordance between two-dimensional ultrasonography (2DUS), three-dimensional ultrasonography (3DUS) and magnetic resonance imaging (MRI) in the assessment of lung volume in fetuses with urinary tract malformations (UTM).

METHODS

This was a cross-sectional study involving 12 pregnancies between 19 and 34 weeks, with various fetal UTM. Pulmonary volume was obtained by 2DUS using the following equation: total lung volume = [right lung antero-posterior diameter (X) x transverse diameter (Y) x cranial-caudal diameter x 0.152 + left lung (X1) x (Y1) x (Z1) x 0.167]. Pulmonary volume by 3DUS was obtained using the virtual organ computer-aided analysis (VOCAL) method with a 30 degrees (VOL30), 18 degrees (VOL18) and 12 degrees (VOL12) rotation. A fast sequence of transverse lung section was also obtained by MRI. The intraclass correlation coefficient was used to evaluate the correlation between the three methods. The paired student t-test was used to compare the means.

RESULTS

There was a strong correlation between the three methods, and the highest correlations were between MRI and VOL18 for the right (ICC = 0.913) and left (ICC = 0.947) lungs. A strong correlation was also found between the lung volumes obtained through MRI and VOL12 as well as VOL18 (p = 0.544 and 0.286, respectively). However, for the left lung there was only a correlation between MRI and VOL12 (p = 0.49).

CONCLUSIONS

There is a good concordance between 3DUS (VOL12) and MRI in the evaluation of lung volume in fetuses with UTM.

Correlação do volume da vesícula vitelínica obtida por meio da ultrassonografia tridimensional com a idade gestacional entre a 7ª e a 10ª semanas usando o método multiplanar

OBJETIVO: Avaliar a correlação do volume da vesícula vitelínica aferida por meio da ultrassonografia tridimensional com a idade gestacional entre a 7ª e a 10ª semanas. MATERIAIS E MÉTODOS: Realizou-se um estudo do tipo corte transversal envolvendo 72 gestantes normais entre a 7ª e a 10ª semanas de gestação. Para o cálculo do volume da vesícula vitelínica, utilizou-se o método multiplanar com intervalo de 1,0 mm entre os planos. Para o volume da vesícula vitelínica foram determinadas médias, medianas, desvios-padrão e valores máximo e mínimo. Para avaliar a correlação entre o volume da vesícula vitelínica e a idade gestacional, foram criados modelos de regressão, sendo os ajustes realizados pelo coeficiente de determinação (R²). RESULTADOS: O volume da vesícula vitelínica (VV) mostrou-se fracamente correlacionado com a idade gestacional (IG), melhor representado pela regressão quadrática, representada pela equação: volume VV = 0,9757 - 0,2499 × IG + 0,0172 × IG² (R² = 0,234). O volume médio da vesícula vitelínica variou de 0,07 cm³ (0,02-0,11) a 0,20 cm³ (0,02-0,74) entre a 7ª e a 10ª semanas de gestação, com média de 0,11 cm³ (± 0,10 cm³). CONCLUSÃO: O volume da vesícula vitelínica correlacionou-se fracamente com a idade gestacional.

Gestational sac volume: comparison between SonoAVC and VOCAL measurements at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVES

To assess the novel three-dimensional (3D) tool, Sonography-based Automated Volume Count (SonoAVC) in the calculation of gestational sac volume at 11 + 0 to 13 + 6 weeks of gestation, to correlate the measurements with those obtained using Virtual Organ Computed-aided AnaLysis (VOCAL) and to study the reproducibility of SonoAVC volume calculation of this irregularly shaped structure.

METHODS

We acquired 3D volumes of the uterus in 65 pregnancies at 11 + 0 to 13 + 6 weeks of gestation. We performed volume calculation of the gestational sac, excluding the fetus and the placenta, using VOCAL with 15 degrees 12-step rotation. We then repeated the calculation with three different SonoAVC settings and compared both techniques. In 30 cases we assessed the reproducibility of the SonoAVC volume calculations.

RESULTS

In 95% of cases it was possible to calculate the gestational sac volume with SonoAVC. This volume increased with advancing gestation and the volumes were expressed as delta values to compare the measurements made with VOCAL and the three different SonoAVC settings. There was no difference between delta values of gestational sac volume calculated using VOCAL and SonoAVC with high and medium growth settings. Reproducibility analysis showed good results.

CONCLUSION

Gestational sac volume calculation is feasible with SonoAVC in most cases and does not differ from that performed using VOCAL. High and medium growth SonoAVC settings seem to be more accurate for gestational sac volume calculation, although larger studies are required for standardization of the technique. The reproducibility analysis showed similar results to those previously published.