The Application Value Of Ultrasound Elastic Strain Ratio And FNAC In Diagnosing Thyroid Nodules Of TI-RADS 4-6 Categories

【Objective:】 To explore the application value of ultrasound elastic strain ratio and FNAC in diagnosing thyroid nodules of TI-RADS 4-6 categories.【Methods】Conventional ultrasonic was applied to 324 thyroid nodules(from 303patients) to observe their size, margin, echo, calcifications, aspect ratio, interior and ambitus bloodstream. Thyroid nodules were classified into groups according to the TI- RADS, and then undergone ultrasonic elastography and the strain ratios of them were recorded. A receiver-operating characteristic curve(ROC)was used to identify the cut-off point in the differential diagnosis of thyroid nodules. The 137 thyroid nodules of TI-RADS 4-6 categories were classified into three groups: group Ⅰ,TI-RADS 4A category; group Ⅱ, TI-RADS 4B category; group Ⅲ, TI-RADS 5-6categories(the pathologically confirmed cases in category 6 have been removed). The strain ratio and FNAC of the three groups were analyzed to find whether there were differences between benign and malignant nodules, and their sensitivity, specificity,accuracy and positive predictive value were calculated.【Result】The boundary value of strain ratio was 0.55. The difference of strain ratio in group I was not statistically significant, while that in group Ⅱ and group Ⅲwere statistically significant. The sensitivity, specificity, accuracy and positive predictive value in group Ⅱand group Ⅲ were 90.9%、75.0%、87.5%、93.0% and85.7%、80.0%、84.6%、94.7% respectively. The accuracy, sensitivity, specificity, positive predictive value of the ultrasound-guided FNAB in the three groups are listed as follows:groupⅠ74.4%、73.3%、75.0%、64.7%; group Ⅱ: 83.9%、87.5%、71.4%、91.3%; group Ⅲ: 89.2%,91.7%, 75.0%, 95.6% respectively.【Conclusion】 Strain ratio is of high application value for the cases in groupⅡ and groupⅢ which have no calcification or less than 1cm or without diffuse lesions.While for the cases in group I and the cases with calcification, more than 1cm or with diffuse lesions in groupⅡ and groupⅢ, the application value of strain ratio was limited, thus other examination methods like fine needle aspiration should be used at the same time to make a definite diagnosis on the nodules as early as possible.