Can color Doppler sonography aid in the prediction of malignancy of thyroid nodules?

Objective. To determine whether color Doppler interrogation of a thyroid nodule can aid in the prediction of malignancy. Methods. We obtained color Doppler images of thyroid nodules undergoing sonographically guided fine-needle aspiration. The color Doppler appearance of each nodule was graded from 0 for no visible flow through 4 for extensive internal flow. The size, sonographic appearance, results of fine-needle aspiration, and surgical pathologic findings, if available, were recorded for each nodule. Results. There were 254 nodules sampled, of which 32 were malignant (all confirmed at surgery) and 177 were benign. Fourteen (43.8%) of the 32 malignant nodules were color type 4, compared with only 26 (14.7%) of the 177 benign nodules (P = .0004, Fisher exact test). Thirteen (40.1%) of the 32 malignant nodules were solid, as were 18 (10.2%) of the 177 benign nodules (P = .006, Fisher exact test). Among solid nodules, the prevalence of malignancy was greater when the nodule was hypervascular (13 [41.9%] of 31) than when the color type was less than 4 (11 [14.7%] of 77; P = .004, Fisher exact test). Conclusions. Solid hypervascular thyroid nodules have a high likelihood of malignancy (nearly 42% in our series). The color characteristics of a thyroid nodule, however, cannot be used to exclude malignancy, because 14% of solid nonhypervascular nodules were malignant.