The value of superb micro-vascular imaging for diagnosis of thyroid nodules

Objective To evaluate the value of superb mircovascular imaging (SMI) for differentiating benign from malignant thyroid nodules by observing the flow distribution characteristics of thyroid solid nodules. Methods From May to June 2014, patients, come from Huadong Hospital of Fudan University, with 68 thyroid nodules were preoperatively evaluated with color Doplor flow image (CDFI) and SMI. All the thyroid nodules were confirmed by pathology. The flow pattern and the color characteristics of thyroid nodule were observed and compared between those two flow imaging technology. The Chi-square test was used to compare the distribution of nodules blood flow patterns between CDFI and SMI and the results were compared with the pathology results. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value were calculated and analyzed. Results For 68 nodules, 41 were benign and 27 were malignant. Both CDFI and SMI showed that malignant nodules were mostly central type vascularization (Ⅲ), whereas the benign nodules were mainly peripheral (Ⅱ) and mixed type vascularization (Ⅳ). SMI is more sensitively in display the nodules blood flow. For benign solid nodules with blood flow distribution type Ⅱ and malignant type Ⅲ, the display rates of SMI are higher than those of the CDFI [68.3% (28/41) vs 46.3% (19/41), 77.8% (21/27) vs 37.0% (10/27)], the differences were statistically significant (χ2=4.04, P<0.05; χ2=9.16, P<0.01). For benign solid nodules with blood flow distribution type Ⅰ, Ⅲ and Ⅳ and malignant solid nodules with blood flow distribution type Ⅰ, Ⅱ and Ⅳ, there were no significant differences between SMI and CDFI. In this study, pathological diagnosis was used as gold standard, nodules with blood flow type Ⅱ and Ⅳ were diagnosed as benign and nodules with blood flow type Ⅲ diagnosis were diagnosed as malignant. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of SMI and CDFI in the diagnosis of thyroid solid nodules were 63.0% vs 88.9%, 80.5% vs 95.1%, 73.5% vs 92.9%, 68.0% vs 92.6%, 76.7% vs 92.3%, respectively. Conclusion SMI is more sensitive to show the real flow and contribute a certain value in differential diagnosis of benign and malignant thyroid nodules. Key words: Thyroid nodule; Superb mircovascular imaging; Diagnosis, differential