Reproducibility of the Ultrasound Measurements of the Thyroid Size and Volume

Author: Mihail Boyanov, Deniz Bakalov

Abstract:

The thyroid ultrasonography is a key imaging method in endocrinology. In the follow-up, especially by another operator, volume differences are found very often due to the very methodology. The subject of this study was to determine the reproducibility of the thyroid size and volume measurements. 30 subjects (25 women, 5 men) referred for diffuse goiter investigations participated. The thyroid sonography was performed by two operators on a Fukuda- Denshi 5500 device (Fukuda Corp., Japan) with a linear-array transducer 7,5 МHz. The subjects were studied three times after full repositioning – twice by the same operator and the third time – by the second operator. The reproducibility (precision) error was calculated as coefficient of variation in % (CV%) for the first operator (intraobserver) as well as between the two operators (interobserver variability). The poorest precision was found when measuring the longitudinal diameter of the thyroid gland. With the thyroid volume raising the precision error rose also. The interobserver precision error (8,3%) was greater than the intraobserver one (6,8%). In conclusion, when following up the thyroid volume the precision error should be kept in mind and the measurements should be whenever possible performed by the same operator on the same device.