Ultrasonographic risk factors of malignancy in thyroid nodules

Between 40 and 50 % of the population will have at least one thyroid nodule, although only 5-8 % will have a malignant one.

The objective of this study was to establish the ultrasonographic characteristics which allow us to distinguish benignity from malignancy in thyroid nodules.

In the study population, inclusion criteria are (1) a single thyroid nodule and (2) multinodular goiter and exclusion criteria are (1) previous thyroid surgery and (2) fine needle aspiration (FNA) in the past month. This study is a double-blind prospective study. The study protocol is as follows: (1) clinical study; (2) ultrasound examination; (3) FNA; and (4) surgery-follow-up. The variables analysed are as follows: a multinodular nodule or goitre; colloid degeneration; morphology; margins; hyperechoic rim; rim thickness; rim morphology; size; angle between the major axis and the skin; echostructure; posterior acoustic findings; calcifications; thick colloid; localization of the intrathyroid nodular tissue; and characteristics in the Doppler scan.

A total of 221 thyroid nodules were analysed. The following ultrasound findings were associated with malignancy (p < 0.05): a nodule with posterior acoustic shadowing; the echotexture of the nodule; intranodular colloid degeneration; nodule margins; nodular morphology; the presence of thick colloid; the angle between the major axis and the skin; characteristics of the intranodular vessels using color Doppler and Doppler energy; and calcifications. In the multivariate analysis, the following factors persisted as predictors of malignancy: the echotexture of the nodule (odds ratio 12.81), microcalcifications (OR 9.05), and chaotic vascularisation in the Doppler energy (OR 43.47).

The high-resolution ultrasound allowed for a more reliable diagnosis of malignancy. The main findings of malignancy were the hypoechogenicity echotexture, microcalcifications, and chaotic intranodular vessels using Doppler energy.