To explore the value of conventional ultrasonography and contrast-enhanced ultrasonography in the extrathyroidal extension of thyroid papillary carcinoma (PTC).

Fifty-four patients with 69 PTCs at Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital) were included, and all of them were examined by conventional ultrasonography and contrast-enhanced ultrasonography before operation. The relationship between the degree of enhancement and extrathyroidal extension of PTCs was analyzed. And the diagnostic efficacy of conventional ultrasonography and contrast-enhanced ultrasonography in predicting the extrathyroidal extension of PTCs was compared.

The postoperative pathological results showed that the incidence of extrathyroidal extension in the 69 PTC nodules was 37.7% (26/69). Among 69 PTCs, 31 (44.9%) showed hypoenhancement, 35 (50.7%) showed isoenhancement, and 3 (5.5%) showed hyperenhancement. Of 31 PTCs with hypoenhancement, extrathyroidal extension was present in 7 (22.6%), and of 38 PTCs with isoenhancement or hyperenhancement, extrathyroidal extension was present in 19 (50.0%); there was a significant difference between them (χ²=5.466, P=0.019). Taking the postoperative pathological diagnosis of extrathyroidal extension as the "gold standard", the sensitivity, negative predictive value, and accuracy of contrast-enhanced ultrasonography in predicting the extrathyroidal extension of PTCs were 92.31%, 95.12%, and 91.30% respectively, which were significantly higher than those (42.31%, 71.70%, and 71.01%, respectively) of conventional ultrasonography (P=0.000, 0.003, and 0.002, respectively). The positive predictive value and specificity of contrast-enhanced ultrasonography and conventional ultrasonography in predicting extrathyroidal extension of PTCs were 85.71% and 90.70%, and 68.75% and 88.37%, respectively; there was no significant difference between them (P=0.180 and 0.725, respectively).

The diagnostic efficiency of contrast-enhanced ultrasonography in predicting extrathyroidal extension of PTC is higher than that of conventional ultrasonography, which is worthy of clinical application and promotion.