Semi-Automatic Identification of the Fetal Profile and Nasal Bone Measurement at the Time of the Routine Mid-Trimester Ultrasound Scan

Abstract

Purpose: This study was designed to compare nasal bone length (NBL) measurements using a manual multiplanar mode with those made using a newer semi-automatic technique (Volume NT™) acquired by an experienced operator as well as measurements done by two independent observers with different levels of ultrasound experience (conventional 2 D vs. Volume NT™).

Materials and Methods: Ultrasound examination was performed prospectively on 81 pregnant women with a singleton pregnancy at the time of their routine mid-trimester ultrasound scan.

Results: The correct mid-sagittal plane of the fetal profile was successfully obtained using the semi-automatic technique in 53 of 81 cases.

Conclusion: NBL measurements using conventional two-dimensional techniques showed significantly higher inter-observer variability than the semi-automatic program. Our study shows the feasibility of using a semi-automatic technique, especially for less experienced operators. Measurements obtained with the semi-automatic technique produced much less variable results around a mean than those obtained with conventional two-dimensional ultrasound.

Zusammenfassung

Ziel: Ziel der vorliegenden Studie war der Vergleich von Messungen des Nasenbeins mittels manuell durchgeführten Multiplanar-Modus mit den Nasenbeinmessungen, die mittels einer neuen semiautomatischen Technik (Volume NT™) von einem erfahrenen Untersucher gewonnen wurden, sowie Messungen zweier unabhängiger Untersucher mit unterschiedlichem Erfahrungsgrad (konventioneller 2D-Ultraschall vs. Volume NT™).

Material und Methoden: Ultraschalluntersuchungen wurden prospektiv bei 81 Schwangeren mit einer Einlingsschwangerschaft zum Zeitpunkt des Zweittrimesterultraschalls durchgeführt.

Ergebnisse: Die genaue Midsagittalebene wurde mit dem semiautomatischen Verfahren erfolgreich bei 53 der 81 untersuchten Fälle gewonnen.

Schlussfolgerungen: Messungen des Nasenbeins mittels konventionellen zweidimensionalen Ultraschalls ergaben eine signifikant höhere Interobserver-Variabilität als die, die mittels semiautomatischen Verfahrens gewonnen wurden. Unsere Studie belegt die Durchführbarkeit eines semiautomatischen Verfahrens, insbesondere bei Anwendern mit geringerer Erfahrung. Messungen, die mittels semiautomatischen Verfahrens gewonnen wurden, ergaben eine deutlich geringere Streuung um den Median als die Ergebnisse, die durch konventionellen 2D-Ultraschall gewonnen wurden.

Key words

face - nasal bone - 3 D ultrasound - image manipulation/reconstruction - observer performance

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