The efficiency of US-elastography in the differential diagnosis of thyroid nodules

One hundred patients with thyroid nodule were included in this study. Their ages were between 18-78 years (mean 45,6). Seventy-nine of them were female and 21 of them were male. All patients were evaluated with B-mode, color Doppler US and elastography by using Hitachi EUB 7500 digital ultrasound equipment. Strain ratio of all nodules was measured two times and mean strain ratio values were calculated for all nodules. 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: Mainly elastic nodule with presence of inelastic (blue) areas not constant during the course of the real time examination, Score 3: Presence of ample and constant inelastic (blue) areas prevalently arranged at the periphery of the nodule, Score 4: Presence of ample and constant inelastic (blue) areas prevalently arranged at the center of the nodule, Score 5: Completely inelastic nodule. Also the nodules were evaluated by the means of number, size, echogenity, border, presence of halo, microcalcifications, inner structure (solid/mixed solid-cystic) and vascularity. All of the color Doppler sonographic and elastographic images were assessed together by two blinded radiologists and were scored in consensus. Grey scale properties, vascularity scores, elasticity scores and mean strain ratios of all nodules were compared with their pathologic diagnosis.Eighty four of all cases were benign and sixteen were malignant. Seventy seven of all benign nodules were colloid nodules (adenomatous, hyperplastic) and seven were follicular adenoma. Fifteen of all malignant nodules were papillary carcinoma and one of them was undifferentiated thyroid carcinoma. Sex, number of nodules, `taller than wide? sign, inner structure, intranodular vascularity and abundant vascularity were not statistically related with malignancy. Hypoechogenicity, blurred margin, absence of halo, microcalcifications and irregular course of vascular structures were statistically related with malignancy. All of 21 nodules with Score 1 elasticity were benign. Fourty-seven of fifty-one nodules with Score 2 elasticity were benign and four of them were malignant. Twelve of 16 nodules with Score 3 elasticity were benign and four were malignant. Four of nodules with Score 4 elasticity were benign and 7 of them were malignant. There was only 1 nodule with Score 5 elasticity and it was malignant. There was a statistically significant relation between high elasticity score and malignancy (p<0,001). The sensitivity of Score 3, 4 and 5 elasticity was 75%, specificity was 81% and accuracy was 80%. The mean strain ratio for benign nodules was 1,889 and 3,334 for malignant nodules. We determined 2,485 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 2,485 (p=0,001). The sensitivity of the strain ratio above 2,485 was 56,2%, the specificity was 85,7%, accuracy was 81%. Presence of microcalcifications had the the highest sensitiviy, specificity and accuracy among all nodule characteristics.US-elastography is an assisting imaging technique to B-mode and Doppler ultrasonography in the differential diagnosis of thyroid nodules.