Ultrasonic Elastography In Differential Diagnosis Of Benign And Malignant Small Thyroid Nodule

ObjectiveIn order to explore the ultrasonic elastic strain ratio’s best diagnosticthreshold and analysis the clinical value of ultrasound elastography in benignand malignant small thyroid nodules, four differential diagnosis methods ofbenign and malignant thyroid nodules, conventional ultrasound, ultrasoundelastography classification, strain ratio, conventional ultrasound combined withultrasound elastography classification, were compared.Materials and Methods138small thyroid nodules from129patients, which were given surgical orbiopsy and confirmed by pathology in the88th Hospital of PLA from October2012to April2013, were collected. All these nodules were found byultrasonography and the diameters were less than1cm.Adopted in our study was HI Vision Preirus color Doppler ultrasonicdiagnostic apparatus with high-frequency linear array probe. The frequency wasfrom5to13MHz. First, all the patients received conventional ultrasound, thenthey received ultrasonic elastography for ultrasound elastography classificationand strain ratio’s measurement.All data were processed by software SPSS17.0.Sensitivity was the verticalaxis, and1-specificity was the abscissa. Using the statistical software, ROCcurve was drawn. And the strain ratio’s optimal threshold value in thedifferential diagnosis of benign and malignant small thyroid nodules wasobtained. Through observing the area under the curve, diagnosis accuracy,specificity, sensitivity, positive predictive value, negative predictive value ofthe four methods, the diagnostic value of the various methods were analyzed. χ2test was adopted to compare the differences among the various diagnostic methods. P≤0.05was defined as statistically significant difference.Results1. In conventional ultrasound, the diagnosis accuracy, specificity,sensitivity, positive predictive value, negative predictive value were79.71%,83.17%,70.27%,60.47%,88.42%.2. In ultrasound elastography classification, the diagnosis accuracy,specificity, sensitivity, positive predictive value, negative predictive value were82.61%,78.22%,94.59%,61.40%,97.53%.3. In conventional ultrasound combined with ultrasound elastographyclassification, the diagnosis accuracy, specificity, sensitivity, positive predictivevalue, negative predictive value were79.71%,73.27%,97.30%,57.14%,98.67%.4. The strain ratio’s optimal threshold value was3.635. The ratio of3.635or greater was malignant, while the ratio of less than3.635was benign. Thediagnosis accuracy, specificity, sensitivity, positive predictive value, negativepredictive value were89.86%,89.11%,91.89%,75.56%,96.77%.5. Pairwise comparisons among the four methods of diagnosis accuracy,specificity, sensitivity, the strain ratio was more specific than conventionalultrasound combined with ultrasound elastography classification, the differencehas statistically significant（P<0.05). The ultrasound elastography classificationand conventional ultrasound combined with ultrasound elastographyclassification were more sensitive than conventional ultrasound, withstatistically significant difference（P<0.05).6. The area under the ROC curve of conventional ultrasound, ultrasoundelastography classification, strain ratio, conventional ultrasound combined withultrasound elastography classification were0.767,0.864,0.905,0.853. Thestrain ratio of the area under the curve was greater than0.9, showing thataccuracy is high. The area under the ROC curve for the remaining three methodslocated between0.7-0.9, showing that these three methods have a certaindiagnostic accuracy for small thyroid nodules.Conclusions1. Ultrasound elastography has certain diagnostic value for small thyroidbenign and malignant nodules. It’s a useful addition to the conventionalultrasound. 2. The ultrasound elastography classification has higher sensitivity. It canimprove the early detection rate of thyroid microcarcinoma in combination withthe conventional ultrasound, and can provide meaningful reference for thethyroid microcarcinoma’s early detection and early treatment.3. The ultrasound elastography strain ratio can semi-quantitative reflect thehardness of the lesions. It is more objective than ultrasound elastographyclassification in judging the benign and malignant small thyroid nodules. Butthey are affected by many factors, so comprehensive judgment is required in theclinical application.