To compare the difference between color Doppler flow imaging (CDFI) and superb microvascular imaging (SMI) in the evaluation of vascular grading and the display rate of vascular in papillary thyroid carcinoma (PTC).

Between June 2015 and December 2015 in Beijing Chaoyang Hosptial, 50 patients with 61 thyroid nodules were detected by ultrasonography, and pathologic types were confirmed as PTC. CDFI and SMI were used to evaluation the same nodule respectively according to Adler′s grading criteria. The different flow characteristics were analyzed by the χ² test.

In CDFI, the vascular grading of 33 patients were 0 ~Ⅰ and these of 28 patients were Ⅱ~Ⅲ by CDFI. In SMI, the vascular grading of 6 patients were 0 ~Ⅰ and these of 55 patients were Ⅱ~Ⅲ by SMI. There was a significant difference between CDFI and SMI for vascular grading (χ²=27.475, P<0.01). In CDFI, 50 patients with PTC showed punctiform and rod-like flow signals, and 5 patients showed more detail internal small branches by CDFI. In SMI, 42 patients with PTC showed punctiform and rod-like flow signals, and 17 patients showed more detail internal small branches. There was a significant difference between CDFI and SMI about the display rate of vascular (χ²=7.011, P<0.01).

Compared with CDFI, SMI is highly improved blood flow sensitivity. It can provide more detail internal small branches in PTC. The characteristics of vascular distribution are similar to strengthening mode of contrast-enhanced ultrasound in PTC, therefore, SMI is worth to further research.