Diagnostic accuracy of ultrasound features in thyroid microcarcinomas

To establish the usefulness of specific ultrasound (US) features as indications for ultrasound-guided fine needle aspiration biopsy (FNAB) in incidentally found infracentimetric thyroid nodules.

The ultrasonographic features and cytology of FNAB samples of 96 histopathologically-proven papillary microcarcinomas (less than 1 cm in long diameter) and 75 less than 1 cm sized benign nodules were analyzed and compared. The risk of malignancy indicated by each US feature was calculated by logistic regression analysis.

Among the US features examined, internal content, shape, margin, echogenicity, and calcifications showed statistically significant differences between benign and malignant infracentimetric nodules. Crude odds ratios (OR) and 95% confidence intervals (CI) for risk of malignancy were, for solid content, OR = 39.3 (95% CI = 3.3-4.64); for taller than wide shape, OR = 14.2 (95% CI = 1.43-14.1); for hypoechogenicity, OR = 3.57 (95% CI = 1.31-9.86); for marked hypoechogenicity, OR = 31.33 (95% CI = 6.63-14.8); and for coarse macrocalcifications, OR = 3.43 (95% CI = 1.04-11.3).

Infracentimetric nodules that are solid, taller than wide, hypoechogenic or markedly hypoechogenic, and have coarse microcalcifications and macrocalcifications have a high risk of malignancy, indicating further assessment.