Us-elastography in the differential diagnosis of benign and malign thyroid nodules

US-ELASTOGRAPHY IN THE DIFFERENTIAL DIAGNOSIS OF BENIGN AND MALIGN THYROID NODULESPurpose:The aim of this study was to evaluate the efficiency differential diagnosis of malign and benign thyroid nodules with a new ultrasound method for measuring the elasticity of tissue by US-elastography.Material and Methods:One hundred and eleven patients with thyroid nodule were included in this study. Their ages were between 17-81 years (mean 51). Ninety-two of them were female and nineteen of them were male. All patients were evaluated with gray scala US, color Doppler US and elastography by using Siemens Acuson Antares with elastography software 13-8 MHz transducer equipment. All images were recorded digitally. Cytological / histopathologic diagnosis was obtained for all cases. The elasticity scores of the lesions were: Score 1: Elasticity in entire nodule, Score 2: Less than %45 of nodule was inelastic (red), Score 3: More than %45 of nodule was inelastic (red), Score 4: Almost whole nodule was inelastic (red), Score 5: Completely inelastic nodule. Also the nodules were evaluated by the means of number, size, echogenity, inner structure (solid/mixed solid-cystic), presence of halo, microcalcifications, border and vascularity. Gray scale properties, vascularity, elasticity scores and mean strain ratios of all nodules were compared with their pathologic diagnosis.Findings:As a result of cytological / histological investigations ninety seven of cases were benign and twenty six were malignant. Eighty six of all benign nodules were hyperplastic, four were adenomatous and seven were thyroiditis. Eight of all malignant nodules were papillary carcinoma, three of them were medullary carcinoma, three of them follicular carcinoma and twelve of malign nodules were suspicious of malignancy weighted. Sex, number and size of nodules, inner structure, vascularity, echogenicity, halo sign and microcalcifications were not statistically related with malignancy. 'Taller-than-wide' sign was statistically related with malignancy.All of ten nodules with Score 1 elasticity were benign. Thirty-six of fourty nodules with Score 2 elasticity were benign and four of them were malignant. Thirty-four of fourty-three nodules with Score 3 elasticity were benign and nine were malignant. Seventeen of twenty six nodules with Score 4 elasticity were benign and nine of them were malignant. There were four nodules with Score 5 elasticity and it was malignant. There was a statistically significant relation between high elasticity score and malignancy (p<0,05). The sensitivity of score 3, 4 and 5 elasticity was 84,6 percent, specificity was 47,4 percent and diagnostic power was 73,9 per cent. The mean strain ratio for benign nodules was 2,60 and 3,50 for malignant nodules. We determined 2,50 as the cut-off point of the strain ratio. There was a statistically significant differance between the nodules with the strain ratio above and below 2,50 (p<0,05). Elastographic feature was most sensitive, spesific and the diagnostic value than the other evaluation of nodules.Result:US-elastography is an assisting imaging technique to B-mode and Doppler ultrasonography in the differential diagnosis of thyroid nodules.Key words: Elastography, Thyroid nodules, nodule stiffness