Comparison of nuchal translucency measurements obtained using Volume NT(TM) and two- and three-dimensional ultrasound

Image Settings Affecting Nuchal Translucency Measurement Using Volume NT Software

PURPOSE

To evaluate the effects of the deviation from the mid-sagittal plane, fetal image size, tissue harmonic imaging (THI), and speckle reduction filter (SRF) on the measurement of the nuchal translucency (NT) thickness using Volume NT software.

MATERIALS AND METHODS

In 79 pregnant women, NT was measured using Volume NT. Firstly, the three-dimensional volumes were categorized based on the angle of deviation in 10° intervals from the mid-sagittal plane. Secondly, the operator downsized the fetal image to less than 50% of the screen (Method A) and by magnifying the image (Method B). Next, the image was magnified until the fetal head and thorax occupied 75% of the screen, and the NT was measured (Method C). Lastly, NT values were acquired with THI and SRF functions on, with each function alternately on, and with both functions off.

RESULTS

The mean differences in NT measurements were -0.09 mm (p<0.01) between two-dimensional (2D) and a deviation of 31-40° and -0.10 mm (p<0.01) between 2D and 41-50°. The intraclass correlation coefficients (ICC) for 2D-NT and NT according to image size were 0.858, 0.923, and 0.928 for methods A, B, and C, respectively. The ICC for 2D-NT and NT with respect to the THI and SRF were 0.786, 0.761, 0.740, and 0.731 with both functions on, THI only, SRF only, and with both functions off, respectively.

CONCLUSION

NT measurements made using Volume NT are affected by angle deviation from the mid-sagittal plane and fetal image size. Additionally, the highest correlation with 2D-NT was achieved when THI and SRF functions were used.

Feasibility of three-dimensional reconstruction and automated measurement of fetal long bones using 5D Long Bone

Objective

To evaluate the feasibility of five-dimensional Long Bone (5D LB), a new technique that automatically archives, reconstructs images, and measures lengths of fetal long bones, to assess whether the direction of volume sweep influences fetal long bone measurements in three-dimensional (3D) ultrasound and 5D LB, and to compare measurements of fetal long bone lengths obtained with 5D LB and those obtained with conventional two-dimensional (2D) and manual 3D techniques.

Methods

This prospective study included 39 singleton pregnancies at 26+0 to 32+0 weeks of gestation. Multiple pregnancies, fetuses with multiple congenital anomalies, and mothers with underlying medical diseases were excluded. Fetal long bones of the lower extremities-the femur, tibia, and fibula were measured by 2D and 3D ultrasound, and 5D LB, by an expert and non-expert examiner. First, we analyzed the 3D ultrasound and 5D LB data according to 2 different sweeping angles. We analyzed intra- and inter-observer variability and agreement between ultrasound techniques. Paired t-test, interclass correlation coefficient, and Bland-Altman plot and Passing-Bablok regression were used for statistical analysis.

Results

There was no statistical difference between long bone measurements analyzed according to 2 different volume-sweeping angles by 3D ultrasound and 5D LB. Intra- and inter-observer variability were not significantly different among all 3 ultrasound techniques. Comparing 2D ultrasound and 5D LB, the interclass correlation coefficient for femur, tibia, and fibula was 0.91, 0.92, and 0.89, respectively.

Conclusion

5D LB is reproducible and comparable with conventional 2D and 3D ultrasound techniques for fetal long bone measurement.

Multimodality 3-dimensional volumetric ultrasound in obstetrics and gynecology with an emphasis in HDlive technique

HDlive (high-definition live or real-time US), a new ultrasound software, combines a movable virtual adjustable light source in a software that calculates the proportion of light reflecting through surface structures, depending on light direction. The light source can be manually positioned to illuminate the desired area of interest. The ultrasound technician can control light intensity to create shadows that enhance image quality. HDlive is an innovation that will render even more realistic images of fetal anatomy and of gynecologic lesions. The full potential of this new technology is yet to be determined and deserves scientific evaluation.

First-trimester assessment of the fetal palate: a novel application of the Volume NT algorithm

We describe a new technique that can facilitate the first-trimester examination of the fetal palate using the Volume NT algorithm (Samsung Medison, Seoul, Korea), a program that automatically detects the exact midsagittal plane of the head and is primarily designed for semiautomatic measurement of the nuchal translucency thickness. Three-dimensional (3D) data sets from the fetal face were captured with Volume NT and subsequently reformatted with the Oblique View software to obtain orthogonal views of the primary and secondary palate in coronal and axial planes, respectively. By testing this method in selected 3D data sets obtained retrospectively (n = 12) and prospectively (n = 28), we were able to extract clinically acceptable views of the fetal palate in all cases. This preliminary report shows that with this new 3D automation development, early evaluation of the fetal palate is feasible and reproducible and could be easily incorporated into the first-trimester sonographic protocol once its ability to detect abnormal cases is demonstrated.

Intra- and interoperator reliability of manual and semi-automated measurements of intracranial translucency

OBJECTIVES

To assess the reproducibility of fetal intracranial translucency (IT) measurements performed manually or with SonoNT(®), a semi-automated caliper placement technique recently introduced for nuchal translucency thickness (NT) measurement.

METHODS

This was a retrospective study using 116 stored images of the head (mid-sagittal plane) from normal fetuses in dorsoposterior position at 11-13 weeks. Two experienced operators each measured the IT separately, twice manually and twice using the semi-automated software. Intraoperator and interoperator repeatability were assessed. The mean of the two manual measurements of the more experienced Operator 2 was considered as the 'gold standard'.

RESULTS

Seven cases were excluded as the IT could not be recognized by the semi-automated software. In the remaining 109 cases, the interquartile range of the mean IT measurement was 1.9-2.4 mm for Operator 1 and 1.8-2.3 mm for Operator 2 for both the manual and the semi-automated IT measurements. The intraoperator SD for manual measurements was 0.091 mm for Operator 1 and 0.088 mm for Operator 2, and for semi-automated measurements it was 0.054 mm for Operator 1 and 0.067 mm for Operator 2. Concerning interoperator bias of the manual measurements, the mean difference between Operator 1 and Operator 2 was - 0.09 (95% CI, - 0.11 to - 0.07) mm. With respect to the gold standard, the mean bias of the semi-automated measurements was 0.01 (95% CI - 0.01 to 0.03) mm for Operator 1 and - 0.09 (95% CI - 0.11 to - 0.07) mm for Operator 2, indicating good agreement.

CONCLUSIONS

Manual IT measurements are reproducible. In addition, IT can be assessed reliably using the semi-automated NT algorithm, leading to standardization of the IT assessment process.