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Purpose: To perform a multicenter prospective study of ultrasound prenasal thickness (PT), and nasal bone length (NBL) measurement at 11-14 weeks' gestation.Methods: Ultrasound PT and NBL determination was performed in 504 normal fetuses and 17 fetuses with Down's syndrome (DS). Measurements were made from mid-sagittal 2D images acquired using a standardized technique during nuchal translucency (NT) examination. PT and NBL values were expressed in multiples of the gestation-specific normal median (MoM) and as the PT/NBL ratio. Information on PT and NBL MoMs was also combined using logistic regression. Results were classified as positive according to whether they were greater than the normal 95th centile for PT, PT/NBL and the DS risk from logistic regression equation or below the 5th centile for NBL.Results: The median value in DS cases and unaffected controls were: PT 1.26 and 0.996 MoM; and NBL 0.596 and 0.993 MoM. The proportion of DS fetuses with positive results was 41% for PT, 65% for NBL, and 82% for both the PT/NBL ratio and DS risk from the logistic regression equation. PT/NBL levels did not vary according to gestational age.Conclusion: The PT/NBL ratio is a valuable first trimester DS screening marker that can be easily determined concomitant with the NT measurement. [ABSTRACT FROM AUTHOR]

In this paper, the segmentation and extraction of features from ultrasound second trimester fetal images have been presented for early detection of Down syndrome. The region of interest and the edges of the segmented region have been obtained using mean shift analysis and Canny operator, respectively. The prime features such as the nasal bone, the palate and the frontal bone have been segmented for estimating the nasal bone length and frontomaxillary facial angle (FMF). It is observed from the results that the rate of growth of nasal bone length is poor and the FMF angle has been found to increase above 85° for fetus with trisomy 21. This analysis may help the physician for better clinical diagnosis. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study is to determine the association between fetal nasal bone length (NBL) and gestational age (GA), biparietal diameter (BPD) and head circumference (HC) in women undergoing prenatal assessments and Down syndrome screening. Methods: Cross-sectional data were obtained from 3,003 women with singleton pregnancies who underwent a prenatal ultrasound examination at the Department of Obstetrics and Gynecology, Cheng Hsin General Hospital between August 2006 and July 2009. Results: Statistical analyses involved linear regression. NBL with GA, BPD and HC as measured between 14 and 35 weeks of gestation were linearly related. Conclusions: Using multiple parameters(GA, BPD and HC) to estimate NBL is more accurate than using than using GA or BPD or HC alone, as indicated by the higher predictive value. [ABSTRACT FROM AUTHOR]