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Nuklearmedizin 2007; 46(01): 01-07
DOI: 10.1055/s-0037-1616621
Original Article
Schattauer GmbH

Intra- and interobserver variability of thyroid volume measurements in healthy adults by 2D versus 3D ultrasound

Intra- und Interobserver Variabilität bei Schilddrüsenvolumenmessungen an gesunden Erwachsenen mittels 2D im Vergleich zu 3D-Ultraschall
P. Andermann
1   Department of Nuclear Medicine, University of Würzburg, Germany
,
S. Schlögl
1   Department of Nuclear Medicine, University of Würzburg, Germany
,
U. Mäder
1   Department of Nuclear Medicine, University of Würzburg, Germany
,
M. Luster
1   Department of Nuclear Medicine, University of Würzburg, Germany
,
M. Lassmann
1   Department of Nuclear Medicine, University of Würzburg, Germany
,
Chr. Reiners
1   Department of Nuclear Medicine, University of Würzburg, Germany
› Author Affiliations
Further Information

Publication History

Received: 07 June 2006

accepted in revised form: 24 October 2006

Publication Date:
08 January 2018 (online)

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Summary

Thyroid volume measurement by ultrasonography (US) is essential in numerous clinical diagnostic and therapeutic fields. While known to be limited, the accuracy and precision of two-dimensional (2D) US thyroid volume measurement have not been thoroughly characterized. Objective: We sought to assess the intra- and interobserver variability, accuracy and precision of thyroid volume determination by conventional 2D US in healthy adults using reference volumes determined by three-dimensional (3D) US. Design, methods: In a prospective blinded trial, thyroid volumes of ten volunteers were determined repeatedly by nine experienced sonographers using conventional 2D US (ellipsoid model). The values obtained were statistically compared to the so-called true volumes determined by 3D US (multiplanar approximation), the so-called gold standard, to estimate systematic errors and relative deviations of individual observers. Results: The standard error of measurement (SEM) for one observer and successive measurements (intraobserver variability), was 14%, and for different observers and repeated measurements (interobserver variability), 17%. The minimum relative thyroid volume change significantly different at the 95% level was 39% for the same observer and 46% for different observers. Regarding accuracy, the mean value of the differences showed a significant thyroid volume overestimation (17%, p <0.01) by 2D relative to 3D US. Conclusion: 2D US is appropriate for routine thyroid volumetry. Nevertheless, the so-called human factor (random error) should be kept in mind and correction is needed for methodical bias (systematic error). Further efforts are required to improve the accuracy and precision of 2D US thyroid volumetry by optimizing the underlying geometrical modeling or by the application of 3D US.

Zusammenfassung

Die Volumenbestimmung der Schilddrüse (SD) durch Ultraschall (US) hat in zahlreichen diagnostischen und therapeutischen Anwendunen einen hohen Stellenwert. Obgleich SD-Volumenbestimmungen durch zweidimensionalen (2D) US fehleranfällig sind, sind Richtigkeit und Präzision dieser Methode noch nicht ausreichend charakterisiert worden. Ziel dieser Arbeit war es, Intra- und Interobserver- Variabilität, Richtigkeit und Präzision der SD-Volumenbestimmung durch den konventionellen 2D-US bei gesunden Erwachsenen anhand von dreidimensionalen (3D) Referenzvolumina zu ermitteln. Probanden, Methoden: Im Rahmen einer prospektiven, verblindeten Studie wurden die SD-Volumina von zehn Probanden mehrmals von neun erfahrenen US-Untersuchern mittels 2D-US (ellipsoides Modell) bestimmt. Die so erhaltenen Messwerte wurden statistisch mit den im 3D-US (multiplanare Approximation) als so genannten Goldstandard ermittelten (wahren) Volumina verglichen, um systematische Fehler und relative Abweichungen einzelner Untersucher abzuschätzen. Ergebnisse: Der Standardfehler (SEM) bezogen auf einen Untersucher und mehrere Messungen (Intraobserver-Variabilität) lag bei 14%, bezogen auf unterschiedliche Untersucher und mehrere Messungen (Interobserver-Variabilität) bei 17%. Die auf dem 95%-Signifikanzlevel unterscheidbare minimale relative SD-Volumenänderung betrug für denselben Untersucher 39%, für unterschiedliche Untersucher 46%. Der Mittelwert der Differenzen ergab hinsichtlich der Richtigkeit eine signifikante überschätzung des SD-Volumens (17%, p <0,01) durch den 2D- gegenüber dem 3D-US. Schlussfolgerung: Der 2D-US ist ein geeignetes Hilfsmittel für die SD-Volumetrie in der Routineanwendung. Allerdings sollte der zufällige Fehler (Faktor Mensch) nicht außer Acht gelassen und berücksichtigt werden, dass methodische Abweichung (systematische Fehler) eine Fehlerkorrektur erfordern. Es bedarf weiterer Bemühungen, um Richtigkeit und Präzision der SD-Volumetrie durch 2D-US zu verbessern, z. B. durch Optimierung der geometrischen Modellierung der SD oder 3D-US.

Keywords

Thyroid volumetry - two-dimensional ultrasound - three-dimensional ultrasound - intraobserver variability - interobserver variability - accuracy - precision - systematic observer error - random observer error

Schlüsselwörter

Schilddrüsenvolumetrie - zweidimensionaler Ultraschall - dreidimensionaler Ultraschall - Intraobserver-Variabilität - Interobserver-Variabilität - Richtigkeit - Präzision - systematischer Fehler - zufälliger Fehl
 

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