Diagnosis Of Small Single Solid Thyroid Nodule With Real-time Ultrasound Elastography

Objective :The purpose of this study was to prospectively evaluate the elastographic appearance of small single solid thyroid nodule showed in 2D and Color Power Doppler ultrasonography and explore the diagnostic value of ultrasonographic elastography for identifying thyroid nodules that were likely to be malignant,with histopathologic analysis as the reference standard.Methods :Fifty-one patients (38 females and 13 males; mean age, 48.6±8.5 years) with single solid thyroid nodule in which with indeterminate results using 2D and Color Power Doppler ultrasonography referred for surgical treatment between Feberuary 2009 to January 2010 were included in this study. Each patient was examined by 2D,Color Power Doppler and real-time Ultrasound Elastography. The diagnostic parameters of grayscale ultrasonography and Color Power Doppler include tumor size, shape, borders, internal echo, calcification , the rear echo change, holo ring and flow distribution features.Then longitudinal scanning of elastography was performed ,and the resultant elastogram was displayed over the B-mode image in a color scale. Green indicated"medium stiffness"of the tissue, blue indicated"hard tissue"and red indicated"soft tissue". the findings on elastography were classified into 5 grades based on the classes of tissue stiffness : I～V grades(gradeⅠwas assigned to nodules with presented elasticity in the whole examined area; gradeⅡwas assigned to nodules with presented elasticity in a large portion of the examined area; gradeⅢwas assigned to nodules with presented elasticity only at the peripheral part of the examined area; gradeⅣwas assigned to nodules with presented no elasticity of the examined area; gradeⅤwas assigned to nodules with presented no elasticity of the examined area and in the posterior shadowing). Study was implemented to compare ultrasonographic results with pathologic findings. Results:1,result of histopathologic examination:Of 51 cases, 37 had a final diagnosis of malignancy on histology ( 5 papillary thyroid microcarcinomas,30 papillary thyroid carcinomas,2 follicular thyroid carcinoma ). 14 lesions were diagnosed as follicular thyroid adenomas.2,result of 2D and Color Power Doppler ultrasonography:51 nodules were hypoechogenicity in which 21 with microcalcifications,2 with soarce calcification,16with irregular margin, 17with holo ring ,34 with Color Doppler typeⅡ,17 with Color Doppler typeⅢ. 2D and Color Power Doppler ultrasonography diagnosed thyroid carcinomas with a sensitivity of 72.97%,a specificity of 57.14%,a accuracy of 68.63%.The positive and negative predictive values were 81.82.63% and 44.44% respectively.3,result of US Elastography:I and II were found in 6 cases ,all benign lesions(follicular adenomas); III in 9 cases,6 benign(follicular adenomas)and 3 carcinoma (1 papillary thyroid carcinoma and 2 follicular thyroid carcinoma ); IV in 30 cases,2 benign (follicular adenomas with calcification) and 28 carcinoma ( 25 papillary thyroid carcinomas and 3 papillary thyroid microcarcinomas ).Ⅴin 6 cases,all carcinomas ( 4 papillary thyroid carcinomas and 2 papillary thyroid microcarcinomas ).Thus,the elasticitic grades IV～Ⅴwere highly predictive of malignancy (P<0.001),with a sensitivity of 91.89%,a specificity of 85.71%,a accuracy of 90.20%.The positive and negative predictive values were 94.44% and 80.00% respectively.Conclusion :Real-time Ultrasound Elastography is a promising imaging technique that can assist in the differential diagnosis of thyroid small single solid nodule that are likely to be malignant. Take the elasticitic grades IV～Ⅴas highly predictive malignancy standard, which has higher sensitivity,specificity and accuracy compared with 2D and Color Power Doppler ultrasonography. An important limitation is probably lack of sensitivity for follicular thyroid carcinoma.