TI-RADS Diagnostic Performance: Which Algorithm Is Superior and How Elastography and 4D Vascularity Improve the Malignancy Risk Assessment

Abstract

Given the increased prevalence of thyroid nodules in the general population (~50%), the real challenge resides in correctly recognizing the suspicious ones. This study proposes to compare four important Thyroid Imaging and Reporting Data Systems (TI-RADS) and evaluate the contribution of elastography and 4D Color Doppler assessment of vascularity in estimating the risk of malignancy. In the study, 133 nodules with histopathological examination were included. Of these, 35 (26.31%) proved to be malignant. All nodules were classified using the four selected systems and our proposed improved score. The American College of Radiology (ACR) and EU TI-RADS had good sensitivity (94.28%, 97.14%) and NPV (93.33%, 95.83%), but fairly poor specificity (31.81%, 23.46%) and PPV (35.48%, 31.19%), with an accuracy of 42.8% and 45.8%, respectively. Horvath TI-RADS had better accuracy of 66.9% and somewhat improved specificity (62.24%), but poorer sensitivity (80%). Russ’ French TI-RADS includes elastography in the risk assessment strategy. This classification proved superior in all aspects (Se: 91.42%, Sp:82.65%, NPV:96.42%, PPV:65.30%, and Acc of 84.96%). The mean strain ratio (SR) value for malignant lesions was 5.56, while the mean SR value for benign ones was significantly lower, 2.54 (p < 0.05). It also correlated well with the response variable: histopathological result (p < 0.001). Although, adding 4D vascularity to the French score generated a similar calculated accuracy and from a statistical point of view, the parameter itself proved beneficial for predicting the malignancy risk (p < 0.001) and may add important knowledge in uncertain situations. Advanced ultrasound techniques definitely improved the risk estimation and should be used more extensively.

Validation of Four Thyroid Ultrasound Risk Stratification Systems in Patients with Hashimoto’s Thyroiditis; Impact of Changes in the Threshold for Nodule’s Shape Criterion

“…It should be kept in mind that US malignancy features and SRSs were established mainly on the basis of the ultrasound image of the most common PTCs [ 41 ]. Effectiveness of SRSs could potentially be improved by the inclusion of elastographic measurements [ 42 , 43 ]. Promising results in this respect were also obtained in patients with HT [ 21 , 44 , 45 ].…”

Comparison of Four Ultrasonography-Based Risk Stratification Systems in Thyroid Nodules with Nondiagnostic/Unsatisfactory Cytology: A Real-World Study

“…Furthermore, differences in the epidemiology of thyroid tumors between Korea and Europe may have also partly affected the results. Each US-based RSS was established for its local population and the epidemiology of thyroid tumors may be varied by the iodine intake and/or genetic variations [ 31 ]. In Korea, where our study was conducted, iodine intake is more than adequate, and PTCs were reported to constitute 92% of thyroid cancers, while FTCs account for only approximately 3% [ 13 , 32 ].…”

“…Therefore, caution should be applied before extrapolating our findings to countries with different dietary iodine contents and/or thyroid tumor epidemiology. Fourth, US-based RSSs that include new US parameters such as elastography or 4-dimensional (4D) vascularity [ 31 ] were not evaluated in the current study.…”

Shear-Wave Elastography in Diffuse Thyroid Diseases

“…Shear waves are generated at low frequencies (10-2000 Hz) and their speed (~1-50 m/s) is related to tissue density [22,24]. SWE is used for evaluation of various tissues: liver [25][26][27], kidney [28,29], breast [30,31], thyroid [32][33][34], prostate [35], and muscles and tendons [36]. There are three types of dynamic elastography: transient elastography (TE), point shearwave elastography (pSWE), and 2D-SWE [37].…”