Ultrasound examination using contrast agent and elastosonography in the evaluation of single thyroid nodules:...

To evaluate the usefulness of ultrasound (US) using contrast agent and elastosonography in the characterization of thyroid nodules.

From November 2006 to July 2007, 23 patients with single thyroid nodules underwent B-mode US and power Doppler, US examination using contrast agent, elastosonography and fine needle aspiration cytology (FNAC). Sixteen patients underwent thyroidectomy.

The 23 nodules included 14 benign and 9 malignant lesions. Analysis of time/intensity curves showed that wash-in (8.8 ± 1.3 vs 12.1 ± 2.6 s; p = 0.002, t-test) and peak enhancement (15.3 ± 4.6 vs 22.2 ± 3.9 s; p = 0.001, t-test) occurred significantly earlier in the malignant nodules than in the benign nodules. Wash-out was monophasic in 70% of benign nodules, but in none of the malignant nodules; polyphasic in 30% of benign nodules and in 100% of malignant nodules. Polyphasic wash-out showed a statistically significant association with malignancy (p = 0.0007, χ(2)). Polyphasic wash-out yielded a sensitivity of 100%, specificity of 71%, positive predictive value (PPV) of 69%, negative predictive value (NPV) of 100% and diagnostic accuracy of 83%. In 78% of the benign nodules (11/14) elastosonographic patterns was 1-2 (elevated elasticity); in 88% of the malignant nodules (8/9) elastosonographic patterns was 3-4 (reduced elasticity). Elastosonography yielded a sensitivity of 88%, specificity of 78%, PPV of 72%, NPV of 91% and diagnostic accuracy of 82%. Elastosonographic patterns 3-4 is associated with malignancy (p = 0.001, χ(2)).

US using contrast agent and elastosonography can be a useful diagnostic tool in the evaluation of single thyroid nodules, particularly when FNAC result is non-diagnostic or suggests a follicular lesion, and in nodules <1 cm.