Diagnostic Accuracy of Contrast-Enhanced Ultrasonography in Papillary Thyroid Microcarcinoma Stratified by Size.

We explored the diagnostic accuracy of ultrasonography (US) in papillary thyroid microcarcinoma (PTMC), studying nodular growths according to size via 3-D color Doppler US (3-DCDUS) and contrast-enhanced US (CEUS). A total of 109 patients undergoing CEUS and surgery of thyroid nodules at the First Hospital of China Medical University between January 2017 and December 2018 were selected for the study, including 77 with post-operative pathologically confirmed PTMC (test group) and 32 with nodular goiter (controls). All nodules were ≤1.0 cm in maximum diameter. After 3-DCDUS, each patient underwent Thyroid Imaging Reporting and Data System (TI-RADS) grading. In both groups, receiver operating characteristic curve analysis of anteroposterior (AP) nodule diameters was conducted, establishing a cutpoint for probable malignancy by CEUS. In the test group (n = 77), grading was as follows: TI-RADS 4a, 23; TI-RADS 4b, 40; TI-RADS 4c, 14. More patients had heterogeneous enhancement or hypo-enhancement (n = 55) than uniform hyper-enhancement or uniform iso-enhancement (n = 22) by contrast-enhanced ultrasonography (CEUS). Control group (n = 32) grading was as follows: TI-RADS 3, 1; TI-RADS 4, 21; TI-RADS 4b, 10. Fewer patients had heterogeneous enhancement or hypo-enhancement (n = 12) than uniform hyper-enhancement or uniform iso-enhancement (n = 20) by CEUS. The diagnostic accuracy of 3-DCDUS or CEUS differed significantly from that of 3-DCD-US + CEUS (p < 0.05), whereas 3-DCDUS and CEUS performed similarly (p > 0.05). At AP diameters of 0.66 cm, the Youden index for diagnosing malignancy by CEUS was maximal. When nodules below this threshold were excluded, both CEUS and 3-DCDUS + CEUS improved significantly in diagnostic accuracy (p < 0.05). CEUS is useful in determining the status (benign vs. malignant) of thyroid nodules, with significantly better accuracy at AP diameters ≥0.66 cm.