Usefulness of ultrasonography is the evaluation of thyroid nodules.
OBJECTIVE
To evaluate the diagnostic capacity of ultrasonography (US) for differentiating between malignant and benign thyroid nodules and its usefulness in obviating unnecessary invasive procedures.


PATIENTS AND METHODS
From January 2012 through December 2014, a total of 321 fine-needle aspiration biopsy (FNAB) procedures were done in 302 patients selected according to the criteria recommended by the American Association of Clinical Endocrinology guidelines and the American Thyroid Association guidelines. We analyzed the following characteristics on US: location, size, morphology, contour, consistency, echostructure, echogenicity, calcifications, and vascularization. We used univariate and multivariate analyses to investigate the relationship between the US findings and thyroid cancer.


RESULTS
The prevalence of malignancy in our study population was 5.92%. The US findings that were significantly associated with a greater probability of malignancy were microcalcifications, central vascularization, and hypoechogenicity. The US findings that were associated with a lower risk of malignancy were areas of colloid degeneration and nodule heterogeneity.


CONCLUSION
Our results suggest that decisions about whether to perform FNAB should be based on the presence of suspicious US findings found with our statistic model rather than on the size of the nodule. Thus, unnecessary FNAB procedures on nodules without suspicious US characteristics can be avoided.