Risk stratification of thyroid nodules with Bethesda category III results on fine-needle aspiration cytology: The additional value of acoustic radiation force impulse elastography.

Chong-Ke Zhao,Bo-Ji Liu,Jun-Mei Xu,Xiao-Wan Bo,Wei Chen,Cheng-Yu Sun,Hui-Xiong Xu,Shen Qu,Dan Wang

doi:10.18632/oncotarget.13685

Abstract

To assess the value of conventional ultrasound, conventional strain elastography (CSE) and acoustic radiation force impulse (ARFI) elastography in differentiating likelihood of malignancy for Bethesda category III thyroid nodules. 103 thyroid nodules with Bethesda category III results on fine-needle aspiration cytology (FNAC) in 103 patients were included and all were pathologically confirmed after surgery. Conventional ultrasound, CSE and ARFI elastography including ARFI imaging and point shear wave speed (SWS) measurement were performed. Univariate and multivariate analyses were performed to identify the independent factors associated with malignancy. Area under the receiver operating characteristic curve (Az) was calculated to assess the diagnostic performance. Pathologically, 65 nodules were benign and 38 were malignant. Significant differences were found between benign and malignant nodules in ARFI. The cut-off points were ARFI imaging grade ≥ 4, SWS > 2.94 m/s and SWS ratio > 1.09, respectively. ARFI imaging (Az: 0.861) had the highest diagnostic performance to differentiate malignant from benign nodules, following by conventional ultrasound (Az: 0.606 - 0.744), CSE (Az: 0.660) and point SWS measurement (Az: 0.725 - 0.735). Multivariate logistic regression analysis showed that ARFI imaging grade ≥ 4 was the most significant independent predictor. The combination of ARFI imaging with point SWS measurement significantly improved the specificity (100% vs. 80.0%) and positive predictive value (100 % vs. 72.9%) in comparison with ARFI imaging alone. ARFI elastography is a useful tool in differentiating malignant from benign thyroid nodules with Bethesda category III results on FNAC.

Highlights

Patients with suspicious thyroid nodules on ultrasound (US) are usually advised to undergo fineneedle aspiration cytology (FNAC)
The malignancy risk of atypia www.impactjournals.com/oncotarget of undetermined significance (AUS)/follicular lesion of undetermined significant (FLUS) nodules is varying and uncertain, the recommended treatment of AUS/FLUS nodules is usually diagnostic thyroid lobectomy or repeat fine-needle aspiration cytology (FNAC) [26, 27]. Most of these nodules are benign at final pathological examinations after surgery or remain as AUS/FLUS nodules on repeat FNAC [28]
AUS/FLUS nodules were found in 11.8% nodules after FNAC and its malignancy rate was 36.9%

Summary

Introduction

Patients with suspicious thyroid nodules on ultrasound (US) are usually advised to undergo fineneedle aspiration cytology (FNAC). US-guided FNAC is a cost-effective and widely-used method to differentiate thyroid nodules with a diagnostic accuracy of 62% to. The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) has standardized the FNAC results and facilitated effective communication among clinicians, radiologists and pathologists [6]. The Bethesda category III classification, that is, atypia www.impactjournals.com/oncotarget of undetermined significance (AUS) / follicular lesion of undetermined significant (FLUS), has remained ambiguous concerning the risk of malignancy and guidelines for management [3, 8]. Bethesda category III nodules (i.e. AUS/FLUS nodules) usually account for less than 7% of FNAC results and the malignancy rate is 5%–15% [9].

Methods

Results

Conclusion