Utility of gray-scale ultrasound to differentiate benign from malignant thyroid nodules

The objective was to assess the utility of gray-scale USG to identify patterns of thyroid nodules and to correlate the characteristics of benign and malignant nodules with pathological diagnosis.

From September 2009 to August 2010, a total of 203 patients (17 males and 186 females), with 240 nodules detected at USG, were included in this study. The characteristics of each nodule were determined. The results were then compared with fine needle aspiration (FNA)/histopathological diagnosis.

Of the 240 nodules examined, 44 (18.33%) were found to be malignant on cytopathology. The malignant nodules demonstrated solid or predominantly solid composition (sensitivity 88.6%, specificity 53.5%); presence of microcalcification (sensitivity 65.9%, specificity 97.9%); irregular or poorly defined margins (sensitivity 84%, specificity 88.7%); anteroposterior (AP) diameter > transverse diameter (sensitivity 77.2%, specificity 80.1%); absent or thick incomplete halo (sensitivity 70.4%, specificity 65.8%); and markedly hypoechoic character (sensitivity 65.9%, specificity 84.6%). Among males, malignant nodules were found in 36.8%, whereas in females the occurrence was 16.7%.

Gray-scale USG features of thyroid nodules are useful to distinguish patients with clinically significant thyroid nodules from those with innocuous nodules despite the overlap of findings. From our study, it is apparent that the USG findings of poorly defined margins, marked hypoechogenicity, microcalcifications, and a taller-than-wider shape have a high diagnostic accuracy for identifying malignant thyroid nodules.