Table 4. Inter-observer agreement on the interpretation of US features.

US features	K value
	Reader 1 vs. Reader 2	Reader 1 vs. Reader 3	Reader 2 vs. Reader 3
Component	0.591	0.563	0.596
Echogenicity	0.427	0.438	0.499
Calcification	0.604	0.586	0.596
Shape	0.696	0.720	0.748
Margin	0.367	0.403	0.510
Halo sign	0.616	0.653	0.638

Note —Reader 1, 2, 3 are reviewers with experience of 2, 5, 6 years, respectively, in thyroid US.