CLINICAL EVALUATION OF REAL-TIME TISSUE ELASTOGRAPHY (RTE) FOR THE DIFFERENTIAL DIAGNOSIS OF THYROID FOLLICULAR LESIONS

Purpose: The diagnosis and management of follicular carcinoma of the thyroid gland remains a controversial topic. Fine needle aspiration, although very sensitive with other types of thyroid cancer, has limited accuracy with follicular lesions. Color-Doppler (CD) imaging has been expected for the differential diagnosis between follicular adenoma and follicular carcinoma, otherwise, the findings obtained by CD imaging could not easily confirmed by cytological and pathological methods. The aim of this study was to evaluate the clinical usefulness of Real-time tissue Elastography (RTE) imaging for the differential diagnosis of thyroid follicular lesions.

Methods and Materials: The 56 follicular tumors obtained from 49 patients were examined by gray-scale US imaging, CD imaging and RTE. Fine needle aspiration cytology was performed in all lesions under US guidance and the site of needle insertion was decided by RTE. A comparative study of these images was made and final diagnosis was determined by the cytological and hisological diagnosis. The images of thyroid follicular lesions obtained by RTE were recognized as four typical patterns as follows, Pattern 1((divide))nodule is relatively homogenous and colored with light green.Pattern 2((divide))the center of nodule is colored with green or sometimes with mix of light green and red. And its periphery is colored with blue.Pattern 3((divide))light green and red mixed inside blue zone. It shows tumor mixed with hard part and relative soft part.Pattern 4((divide))the whole tumor is hard and displayed in blue.

Results: All the follicular tumor was cytologically and histopathologically diagnosed finally. In this series, 30 adenomatous nodules, 21 follicular adenomas and 5 follicular cancers were found. Of the 51 benign thyroid nodule, 48 cases (94.1%) demonstrated as Pattern 1, 3 cases demonstrated as Pattern 3. On the other hands, all the follicular cancer were recognaized as Pattern 2.

Conclusions: In follicular cancer, the difference of ealasticity from core of the tumor and periphery of the tumor is supposed to be caused by the difference of hypercellurality. RTE can provide new useful information for the differential diagnosis of thyroid follicular lesions.