Combined Shear Wave Elastography and EU TIRADS in Differentiating Malignant and Benign Thyroid Nodules

SIMPLE SUMMARY: Grey scale ultrasound assessment is primarily used in the differential diagnosis of thyroid nodules. However, in recent years the assessment of tissue elasticity using shear wave elastography (SWE) has been suggested to have additional diagnostic value in thyroid cancer diagnosis. The aim of the present study was to evaluate the diagnostic efficiency of SWE in combination with grey scale ultrasound malignancy risk-stratification based on the European (EU) thyroid management guideline based on nodule size stratifications and indeterminate cytology status. We established that the combined approach had high diagnostic efficacy in differentiating malignant and benign nodules > 1 cm. However, in nodules with indeterminate cytology the approach highly discriminated benign nodules but resulted in low sensitivity which was indicative of an undesirable high false negative rate. The combination of SWE and the EU guideline is therefore most useful when evaluating non-micro-nodules based on size. ABSTRACT: Although multimodal ultrasound approaches have been suggested to potentially improve the diagnosis of thyroid cancer; the diagnostic utility of the combination of SWE and malignancy-risk stratification systems remains vague due to the lack of standardized criteria. The purpose of the study was to assess the diagnostic value of the combination of grey scale ultrasound assessment using EU TIRADS and shear wave elastography. 121 patients (126 nodules–81 benign; 45 malignant) underwent grey scale ultrasound and SWE imaging of nodules between 0.5 cm and 5 cm prior to biopsy and/or surgery. Nodules were analyzed based on size stratifications: <1 cm (n = 43); 1–2 cm (n = 52) and >2 cm (n = 31) and equivocal cytology status (n = 52), and diagnostic performance assessments were conducted. The combination of EU TIRADS with SWE using the SD parameter; maintained a high sensitivity and significantly improved the specificity of sole EU TIRADS for nodules 1–2 cm (SEN: 72.2% vs. 88.9%, p > 0.05; SPEC: 76.5% vs. 55.9%, p < 0.01) and >2 cm (SEN: 71.4% vs. 85.7%, p > 0.05; SPEC: 95.8% vs. 62.5%, p < 0.01). For cytologically-equivocal nodules; the combination with the SWE minimum parameter resulted in a significant reduction in sensitivity with increased specificity (SEN: 60% vs. 80%; SPEC: 83.4% vs. 37.8%; all p < 0.05). SWE in combination with EU TIRADS is diagnostically efficient in discriminating nodules > 1 cm but is not ideal for discriminating cytologically-equivocal nodules.