Objective To explore the roles of conventional ultrasound and contrast-enhanced ultrasound in distinguishing between benign and malignant thyroid nodules with calcification. Methods A total of 102 solid thyroid nodules with calcification in 76 patients were evaluated by conventional ultrasound alone and conventional ultrasound combined with contrast-enhanced ultrasound.The features obtained through conventional ultrasound alone and that combined with contrast-enhanced ultrasound were scored,and the diagnostic performance of the two methods was analyzed based on the final pathological results. Results The distribution of microcalcification(P<0.0001),aspect ratio>1(P=0.039),unclear boundary(P=0.027),ring enhancement around nodules(P=0.000),and the degree(P=0.000)and uniformity(P=0.001)of enhancement for the non-calcified part were statistically different between benign and malignant nodules.Compared with conventional ultrasound alone,conventional ultrasound combined with contrast-enhanced ultrasound significantly improved the area under the curve(0.841 vs.0.701,P<0.001)and specificity(97.06% vs. 44.12%,P=0.007),without significant change in sensitivity(67.55% vs. 73.53%,P=0.727). Conclusions The combination with contrast-enhanced ultrasound can improve the performance of conventional ultrasound in the differential diagnosis of benign and malignant thyroid solid nodules with calcification.Eight malignant signs include solid,hypoechoic,microcalcification,aspect ratio,and blurred edges detected by conventional ultrasound,and non-circular enhancement around nodules,low enhancement and non-uniform enhancement of solid parts detected by contrast-enhanced ultrasound.A solid thyroid nodule with calcification presenting five or more malignant signs highly suggests malignancy.
Keywords: calcification; contrast-enhanced ultrasound; diagnosis; thyroid solid nodules.