Ultrasonographic United Stiffness Score System: Resolving the Discrepancy between Acoustic Radiation Force Impulse and Real-time Elastography in Evaluating the Thyroid Nodules Stiffness

Abstract

Objective: The aim of this study was to assess the ultrasonographic united stiffness score system (UUSSS) in diagnosing thyroid nodules, and retrospectively analyze the discrepancy between acoustic radiation force impulse (ARFI) and real-time elastography (RTE).Methods:170 conventional ultrasound (US) proven thyroid nodules in 70 patients were included and all were examined by RTE and ARFI. RTE and ARFI were first analyzed respectively, comparing with pathological findings. Then nodules have discrepancy between ARFI and RTE were retrospectively analyzed by UUSSS. Results:The AUC (area under curve) of ARFI combined RTE in 170 nodules was 0.87 (sensitivity=79.4% (54/68), specificity=84.3% (86/102), PPV=77.1% (54/70), NPV=86.0% (86/100), accuracy for ARFI were 82.4% (140/170), relatively to RTE was 0.83, 80.9%, 65.7%, 61.1%, 83.8%, 71.8%.The AUC of UUSSS was 0.876 (sensitivity=83.8% (57/68), specificity=87.3% (89/102), PPV=81.4% (57/70), NPV=89.0% (89/100), accuracy for UUSSS was 85.9% (146/170). The difference between area under UUSSS and RTE ROC curves was statistically significant (p<0.05), but was insignificant between UUSSS and ARFI (p=0.2245). There were 47 thyroid nodules had discrepancy in assessing the stiffness between ARFI and RTE. In these nodules, the accuracy of UUSSS was 83.0% (39/47), there were significant difference compare to RTE (20/47) (p=0.000), and ARFI (27/47) (p=0.012). Conclusions:UUSSS is useful to increase the diagnostic accuracy compare to independent RTE and ARFI, especially for those had discrepancy between ARFI and RTE. UUSSS is easy and convenient to re-evaluate stiffness on RTE and ARFI basis, and it place no additional cost burden.