Clinical Significance of Preoperative Studies in Diagnosis of Thyroid Nodule : FNAC, Ultrasonography, Computed Tomography

Koh, Joong Wha; Shin, Jee Churl; Kim, Hui Zun; Park, Seung Ku

Abstract

BACKGROUND AND OBJECTIVES: It is critical to distinguish benign from malignant thyroid nodule and to select a patient for surgery. Fine needle aspiration cytology(FNAC) and various radiologic techniques are used in the evaluation of thyroid nodule. The purpose of this study is to evaluate the diagnostic accuracy of preoperative FNAC, ultrasonography(US) and computed tomography(CT) in thyroid nodule, and to identify the reliable factors of radiologic imaging in the differential diagnosis of thyroid nodule. MATERIALS AND METHOD: Retrospectively, we reviewed 34 patients among 50 patients with thyroid nodule who were evaluated by FNAC, US and CT and operated on at our Department from June 1995 to December 1998. By comparing the preoperative FNAC results, US and CT findings with postoperative pathologic diagnosis, the results were as followed.
RESULTS
Overall diagnostic accuracy of FNAC, US, and CT was 84.4%, 88.2%, 79.4%. Solid nature, ill defined margin, calcification, lymphadenopathy on US imaging indicated the possibility of malignancy. Solid nature, ill defined margin, lymphadenopathy on CT imaging indicated the possibility of malignancy.
CONCLUSION
This study suggests that FNAC has a high sensitivity(75.0%) and specificity(93.8%) rate and it is therefore a valuable initial diagnostic procedure. US has higher diagnostic accuracy than computued tomography.