Accuracy and reliability of thyroid volumetry using spiral CT and thyroid volume in a healthy, non-iodine-deficient Chinese adult population

Abstract Objective The purpose of this study was to assess the accuracy and reliability of thyroid volumetry using spiral CT and to investigate thyroid volumes for a healthy, non-iodine-deficient adult population in southwestern region of China. Materials and methods Spiral CT was performed in phantoms and adult subjects with normal thyroid, and the volumes were measured by observers with 5 years or more of CT experience. The phantom volumes and the thyroid volumes of all subjects were noted. Results For the thyroid phantoms, there was no significant difference between the true and CT calculated volumes ( t = 0.862, P = 0.399), and the correlation was excellent (ICC = 0.9995, P = 0.000). In the subjects for reliability analysis, the intraobserver or interobserver differences for CT volumetric measurement of thyroid were not significant ( P > 0.05). The intraobserver or interobserver correlations were very high (ICC > 0.99, P < 0.001). In the subjects for population analysis, the median of the thyroid volumes was 11.45 cm3 . The nonparametric Mann–Whitney U -test showed no significant difference for the thyroid volume between sexes ( U = 4388.00, Z = −1.118, P = 0.264). The nonparametric Kruskall–Wallis test showed no significant difference in all age groups ( χ2 = 13.466, P = 0.062). There was a slight negative correlation between the thyroid volume and age ( r s = −0.166, P = 0.019). Conclusion The accuracy and reliability of multi-slice spiral CT in measuring thyroid volume are very high. The thyroid volumes are not significantly difference between genders or among decades for the healthy, non-iodine-deficient adult population in southwestern region of China.