Computed Tomography Findings and Diagnosing Thyroid Neoplasms

Since no diagnostic method has been established to distinguish follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA), surgery has been the only way to reach a diagnosis of follicular neoplasm. Here we investigated the computed tomography (CT) features of follicular neoplasms, toward the goal of being able to identify specific CT features allowing the preoperative differentiation of FTC from FTA. We retrospectively analyzed the cases of 205 patients who underwent preoperative CT of the neck and were histopathologically diagnosed with FTC (n = 31) or FTA (n = 174) after surgery between January 2002 and June 2016 at several hospitals in Japan. In each of these 205 cases, non-enhanced and contrast-enhanced CT images were obtained, and we analyzed the CT features. On univariate analysis, inhomogeneous features of tumor lesions on contrast-enhanced CT were more frequently observed in FTC than in FTA (p= 0.0032). A multivariate analysis identified inhomogeneous features of tumor lesions on contrast-enhanced CT images as an independent variable indicative of FTC (p= 0.0023). CT thus offers diagnostic assistance in distinguishing FTC from FTA. Key words: computed tomography, follicular thyroid carcinoma, follicular thyroid adenoma, preoperative diagnosis Preoperative diagnostic methods have not been established to distinguish follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA). Although ultrasonography (US) -guided fine needle aspiration (FNA) cytology of thyroid nodules has become the dominant modality for assessing the need for a resection of thyroid nodules, among 219 patients with preoperative FNAs reported as suspicious for follicular neoplasm, only 19 (8.7 %) were actually FTCs. The rate of invasive FTCs among all follicular neoplasms is only 2 % [3]. However, since the malignant potential of follicular neoplasms can rarely be determined from a cytological evaluation alone, many patients are advised to undergo surgical resection. We conducted the present study to determine specific CT features for distinguishing FTCs from FTAs