Yonsei Med J.  2015 Sep;56(5):1345-1351. 10.3349/ymj.2015.56.5.1345.

Image Settings Affecting Nuchal Translucency Measurement Using Volume NT(TM) Software

• Cho HY
• Kim YH
• Park YW
• Kim SY
• Lee KH
• Yoo JS
• Kwon JY

• KMID: 2163627
• DOI: http://doi.org/10.3349/ymj.2015.56.5.1345

Abstract

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(TM) software.
MATERIALS AND METHODS
In 79 pregnant women, NT was measured using Volume NT(TM). Firstly, the three-dimensional volumes were categorized based on the angle of deviation in 10degrees 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 31-40degrees and -0.10 mm (p<0.01) between 2D and 41-50degrees. 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(TM) 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.

Keyword

Volume NT(TM) software; nuchal translucency; angle deviation; image size; tissue harmonic imaging; speckle reduction filter

MeSH Terms

Adult
Embryo, Mammalian/*ultrasonography
Female
Humans
Image Enhancement/*methods
Imaging, Three-Dimensional/*methods
*Nuchal Translucency Measurement/methods
Pregnancy
Sensitivity and Specificity
Software

Figure

• 

  Fig. 1 Representative images of nuchal translucency (NT) thickness measurements using Volume NT™ at three different magnifications: (A and B) automated NT measurement with the fetal head and thorax occupying less than 50% of the image (method A); (C and D) automated mid-sagittal reconstruction in low magnification then zoomed-in to magnify the fetus so as to occupy the whole screen (method B); (E and F) automated NT measurement with fetal head and thorax occupying the whole screen (method C).

• 

  Fig. 2 Images of effects of tissue harmonic imaging (THI) and speckle reduction filter (SRF): (A) THI and SRF functions on; (B) THI function on; (C) SRF function on; (D) both functions off.

• 

  Fig. 3 Bland-Altman plots of the variability of nuchal translucency (NT) thickness measurements. (A) Using two-dimensional (2D) ultrasound and method A of Volume NT™, (B) 2D ultrasound and method B, and (C) 2D ultrasound and method C. Dotted lines represent mean±2 SD. US, ultrasonography.

• 

  Fig. 4 Bland-Altman plots of the variability of nuchal translucency (NT) thickness measurements. (A) Using two-dimensional (2D) ultrasound and the tissue harmonic imaging (THI) and speckle reduction filter (SRF) features of Volume NT™, (B) 2D ultrasound and THI of Volume NT™, (C) 2D ultrasound and SRF of Volume NT™, and (D) 2D ultrasound and both functions off. Dotted lines represent mean±2 SD. US, ultrasonography.

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