@@

Objective To investigate the value of CT value in differential diagnosis of benign and malignant thyroid calcification.Methods The CT plain scan data of 48 cases of thyroid benign calcification and 26 cases of thyroid malignant calcification confirmed by pathology were analyzed retrospectively,and the CT values of 74 cases of thyroid calcification were measured.The best threshold and the maximum area under the receiver operator characteristic(ROC)curve for differentiating benign and malignant thyroid calcification were determined by plotting ROC curve,and the corresponding specificity,sensitivity,positive predictive value,negative predictive value,false positive rate,false negative rate,accuracy and Jordan index were calculated.Then the optimal threshold value was used as a parameter for differential diagnosis of benign and malignant thyroid calcification,and we adoptted χ2 analyze the statistical difference between benign and malignant thyroid calcification in CT gray value.Results The area under the ROC curve was 0.814,and the 95%confidence interval(CI)was 0.712-0.915.When the CT value was 869.5HU(for the convenience of 870HU),the specificity was 69.2%,the sensitivity was 81.3%,the positive predictive value was 64.3%,the negative predictive value was 82.6%,the false positive rate was 20.8%,and the false negative rate was 30.8%,the accuracy was 75.7%and the maximum of the Youden index was 0.505.When 870HU was taken as the differential diagnosis parameter of thyroid benign and malignant calcification(χ2=16.795,P<0.001).Conclusion When the CT value is 870HU,it has important value in differential diagnosis of benign and malignant thyroid calcification.