Fig. 2

(a) A benign nodule. It is iso-echoic relative to the thyroid, and surrounded by a hypo-echogenic halo. (b) A benign cystic nodule with multiple colloids, which are seen as hyper-echoic spots with comet-tail. (c) A benign nodule with hypo-echoic cystic spaces resulting in a spongiform or honeycomb appearance. (d) A benign nodule with eggshell calcification. Note the acoustic shadowing produced by the calcific ring. (e) A benign nodule with eggshell calcification. (f) A benign nodule with peripheral vascularity on Doppler assessment