Abstract
PurposeTo compare shear wave elastography (SWE) and Afirma™ gene expression classifier (GEC) for diagnosis of malignancy in thyroid nodules (TNs) with Bethesda Classification (BC) III or IV indeterminate cytology.MethodsThis preliminary single-center prospective study was approved by the Institutional Review Board. We evaluated 151 consented patients with 151 indeterminate TNs (123 BC III, 28 BC IV) on fine-needle aspiration biopsy (FNAB). B-mode ultrasound, vascularity, and SWE were performed prior to FNAB. TN stiffness was measured as shear wave velocity (SWV) in meters per second (m/s). The stiffest area of the TN was selected for SWV measurement. GEC testing was performed with a second FNAB. Surgery was recommended for GEC-suspicious TNs, or GEC-benign TNs with two or more worrisome B-mode US features.ResultsSurgical pathology confirmed 31 malignant TNs. Among the GEC-suspicious group, 28 of 59 TNs were malignant. The SWV value of ≥3.59 m/s was the best cut-off for malignancy risk based on the receiver operating curve (ROC). Twenty-six malignant TNs had SWV ≥ 3.59 m/s. The sensitivity and specificity for SWV ≥ 3.59 m/s were 83.9 and 79.2%, respectively. Positive predictive value (PPV) was 51.0% and negative predictive value (NPV) was 95.0%. For the GEC-suspicious group, sensitivity, specificity, PPV, and NPV were 90.3, 74.2, 47.5, and 96.7%, respectively. In multivariate analysis, SWV and GEC-suspicious were significant predictors of malignancy, but B-mode features and vascularity were not.ConclusionThis preliminary study indicates that SWE and GEC are independent predictors of malignancy in TNs with BC III or IV.
Highlights
Management of thyroid nodules (TNs) with indeterminate fine-needle aspiration biopsy (FNAB) has been a major challenge for thyroid experts
We previously reported that TN stiffness measured by Virtual touch imaging quantification (VTIQ)-generated shear wave elastography (SWE) is an independent predictor of thyroid cancer (TC) when TNs with all Bethesda classifications were included
All TNs were evaluated with a high-resolution US and FNAB
Summary
Management of thyroid nodules (TNs) with indeterminate fine-needle aspiration biopsy (FNAB) has been a major challenge for thyroid experts. The Bethesda System for the Reporting of Thyroid Cytopathology renders standardized reporting criteria for TN FNAB cytopathology. Bethesda categories (BC) include: I (non-diagnostic or unsatisfactory), II (benign), III (atypia of undetermined significance or follicular lesion of undetermined significance), IV (follicular neoplasm or suspicious for follicular neoplasm), V (suspicious for malignancy) or VI (malignant) [1]. Indeterminate cytology categories include BC III and BC IV. 15–30% of TN aspirations are interpreted as indeterminate, but the majority has benign surgical pathology. Among these patients, the risk for serious surgical complications ranges between 2–10% [2]
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