Abstract
Objective To establish a normal range of nasal-bone length at 16-24 weeks' gestation by the use of threedimensional (3D) ultrasound and to investigate the effect of deviations from the exact mid-sagittal plane on the measurement of nasal-bone length. Methods We acquired 3D volumes of the fetal profile from 135 normal fetuses at 16-24 weeks' gestation. The multiplanar mode was used to obtain the exact midsagittal plane and to produce parasagittal and oblique views of the fetal face. Nasal-bone length was measured in each plane and the sonographic landmarks of each profile view were examined. Results Nasal-bone length increased with gestational age from a mean of 4.1 mm at 16 weeks to 7.1 mm at 24 weeks. There was a tendency to underestimate nasal-bone length when the measurements were taken in parasagittal planes and to overestimate the measurements when they were taken in oblique views, compared to the exact mid-sagittal plane. The mean difference in nasalbone length from the one in the mid-sagittal plane was 0.42 and 0.63 mm for parasagittal measurements at 1 and 2 mm, respectively, from the midline, -0.08 and -0.51 mm for oblique measurements at 10° and 20° rotation along the z-axis and -0.69 mm for rotation of 20° along the z-axis and 10° along the y-axis. The vomeral bone was the only sonographic landmark defining the exact mid-sagittal plane of the face that was not visible in the parasagittal and oblique planes. Conclusions Parasagittal and oblique scanning planes may produce different degrees of under-or overestimation of nasal-bone length compared to measurements systematically taken in the exact mid-sagittal plane. Inclusion of the vomeral bone in the definition of the exact mid-sagittal plane of the face could improve the reproducibility of measurements of nasal-bone length.
Original language | English |
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Pages (from-to) | 285-290 |
Number of pages | 6 |
Journal | Ultrasound in Obstetrics and Gynecology |
Volume | 36 |
Issue number | 3 |
DOIs | |
Publication status | Published - Sep 2010 |
Keywords
- 3D ultrasound
- Mid-sagittal plane
- Nasal bone
- Vomer
ASJC Scopus subject areas
- Obstetrics and Gynaecology
- Radiology Nuclear Medicine and imaging
- Radiological and Ultrasound Technology
- Reproductive Medicine
- Medicine(all)