Efficacy of thyroid ultrasound elastography in differential diagnosis of small thyroid nodules.

OBJECTIVE

To explore the efficacy of thyroid ultrasound (US) elastography in differential diagnosis of small thyroid nodules.

METHODS

This HIPAA-compliant study was approved by the Institutional Review Board and all patients provided written informed consent. Thirty-five patients with 38 small thyroid nodules as seen on transverse ultrasound image formed our study population. An US examination and a separate thyroid elastography examination with pulsation from the carotid artery used as the compression source were performed before fine-needle aspiration. Baseband US data were acquired for off-line elastography processing, where a semi-quantitative index for each nodule was calculated. The Kruskal-Wallis nonparametric rank sum test was used to assess equality of population means among the different types of thyroid nodules. Maximum likelihood estimation of the curve parameters for a binomial receiver operating characteristic (ROC) curve was performed.

RESULTS

Elasticity contrast index calculated with elastography was effective in distinguishing between small papillary thyroid carcinomas (PTMC, n=8) and other lesions (n=30) in small thyroid nodules (p=0.0036). The area under the ROC curve for diagnosing PTMCs was 0.812 with a 95% confidence interval of 0.653-0.920. The cut-off value of ECI of 3.6 led to a sensitivity of 100% and a specificity of 60% for detecting PTMCs.

CONCLUSION

Noninvasive evaluation of small thyroid nodules is possible using thyroid US elastography with in vivo compression to pick out the most suspicious thyroid nodules for fine-needle aspiration (FNA) and avoid FNA in benign nodules.