Shear wave elastography combined with the thyroid imaging reporting and data system for malignancy risk stratification in thyroid nodules

Abstract

To retrospectively evaluate the diagnostic performance of shear wave elastography (SWE) and thyroid imaging reporting and data system (TI-RADS) in differentiating malignant and benign thyroid nodules. A total of 313 thyroid nodules in 227 patients were included. All thyroid nodules were underwent SWE and TI-RADS before fine needle aspiration biopsy and/or surgery. SWE elasticity indices of the maximum (Emax), mean (Emean), minimum (Emin) and elastic ratio (ER) in thyroid nodules were measured. Nodules with solid component, marked hypoechogenicity, poorly defined margins, micro-calcifications, and a taller-than-wide shape were classified as suspicious at gray-scale ultrasonography. The level of TI-RADS was determined according to the number of suspicious ultrasonography features. The combined methods of SWE and TI-RADS in thyroid nodules were calculated. In the 313 nodules, 194 were malignant, and 119 were benign. SWE and TI-RADS were significantly higher in malignant nodules than benign nodules (P < 0.001). The most accurate SWE cut-off value, 51.95 kPa for Emax, achieved a sensitivity of 81.44% and a specificity of 83.19% for discriminating malignant nodules from benign nodules. There are two methods in combination with SWE and TI-RADS. The one is "tandem" method, which has a higher specificity (95.80%), positive likelihood ratio (18.16) and positive predictive value (96.73%). The other one is "parallel" method, which shows sensitivity (94.85%), negative likelihood ratio (0.07) and negative predictive value (90.00%).We believe that the methods could be used as a simple tool to stratify the risk of thyroid nodules accurately.

Keywords: diagnostic performance; shear wave elastography (SWE); thyroid imaging reporting and data system (TI-RADS); thyroid nodules; “tandem” and “parallel”.

Figure 1. Flow chart of the study group

FNA: fine-needle aspiration cytology.

Figure 2. Receiver-operating characteristic (ROC) curves for the EIs of SWE and TI-RADS

Figure 3. Images in a 64-year-old woman who underwent a routine checkup

An 11-mm left thyroid solid nodule with marked hypoechogenicity, poorly defined margins, and micro-calcifications was found on gray-scale US, was classified as TI-RADS 4c a. The E_max value of SWE of the nodule was 258.4 kPa b. This thyroid nodule was diagnosed as papillary thyroid carcinoma after surgery. Pathological images (c. HE 10×10). Images in a 59-year-old woman who underwent a routine checkup. An 18-mm left thyroid nodule with macro-calcification was found on conventional US, was classified as TI-RADS 4a d. The E_max value of SWE of the nodule was 63.2 kPa e. The post-operational histopathology was nodule gotiers. Pathological images (f. HE 10×10).