Sonographic Features of Benign Thyroid Nodules

Objective . To prospectively determine the sonographic findings of nodular hyperplasia of the thyroid, to compare these with reported findings associated with malignancy, and to assess interobserver reliability. Methods . Seventy thyroid nodules were scanned, and then biopsies of the nodules were performed under sonographic guidance with fine‐needle cytologic analysis; in all cases images were reviewed by 2 experienced radiologists without knowledge of clinical outcome. Findings reported associated with malignancy were specifically assessed. Interobserver agreement between the expert and secondary readers for each finding was calculated by the κ or weighted κ statistic and the Fisher exact test of independence. Results . There were 68 benign and 2 malignant nodules in a population of 63 female and 7 male patients. The mean benign nodule size was 2.9 cm; 60% were solid; 54% were hypoechoic; 59% were microlobulated or macrolobulated; 47% had central vascularity; 24% contained calcifications; and 82% were elliptical in shape. There was very good interobserver reliability for the presence of calcium (κ = 0.91) and good agreement for the presence and location of vascularity (κ = 0.75) and the amount of cystic components (κ = 0.62; all P < .01). Conclusions . Sixty‐nine percent of benign nodules had at least 1 finding reported previously as associated with malignancy. The interobserver reliability of the sonographic findings was good to very good for 3 of the 5 findings assessed.