Shear wave elastography of thyroid nodules in routine clinical practice: preliminary observations and utility for detecting malignancy.

Abstract

To evaluate real-time shear wave ultrasound elastography (SWE) for characterizing focal thyroid lesions in routine clinical practice. Seventy-four patients with 81 focal thyroid lesions undergoing conventional US with needle cytology also underwent SWE. Absolute and relative SWE stiffness measurements on colour-coded elastograms were correlated with cytology and their discriminatory performances assessed. Seventeen nodules were malignant (13 papillary, 4 other cancers), 45 benign (43 hyperplastic nodules, 2 focal thyroiditis), 5 indeterminate ("follicular lesions"), and 5 had inadequate cytology. SWE results were higher in malignant than benign nodules (P values 0.02-0.05) although their discriminatory performances were mediocre (AUCs 0.58-0.74). The most accurate SWE cut-off, 34.5 kPa for a 2-mm region of interest, achieved 76.9 % sensitivity and 71.1 % specificity for discriminating papillary cancer from benign nodules. No thresholds produced high sensitivity without lowering specificity appreciably, and vice versa. Nodule size correlated with SWE for benign nodules (P < 0.01). Intranodular cystic change or calcification did not influence SWE. Qualitatively, elastographic artefacts and foci lacking colour elasticity signal occurred in some solid nodules. Although malignant nodules are generally stiffer than benign nodules, the precision results do not suggest a definitive role for SWE, at present, in identifying or excluding thyroid malignancy. • Shear wave ultrasound elastography (SWE) offers new insight into thyroid disease. • Papillary cancers have higher SWE indices (equating to higher stiffness) than benign nodules. • SWE appears limited in terms of identifying or excluding thyroid malignancy accurately. • Vertically aligned elastographic artefacts can occur in thyroid SWE. • Areas lacking SWE colour signal can occur in some solid thyroid nodules.