Computed Tomography Features of Follicular Thyroid Carcinoma: Comparison with Papillary Thyroid Carcinoma

Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine Received June 20, 2010 ; Accepted September 27, 2010 Address reprint requests to : Yoon Jung Choi, M.D., Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 78, Saemunan-gil, Jongno-gu, Seoul 110-746, Korea. Tel. 82-2-2001-1563 Fax. 82-2-2001-1030 E-mail: [email protected] Purpose: The purpose of this study is to analyze the computed tomography (CT) features of follicular thyroid carcinoma (FTC) as compared to those of papillary thyroid carcinoma (PTC) to identify the characteristic imaging features of FTC. Materials and Methods: The following CT features were analyzed to compare FTCs (n = 17) and PTCs (n = 27): size, shape, margin, internal composition, calcification, enhancement homogeniety, extrathyroidal extension, lymph node (LN) metastasis and the density and degree of enhancement (qualitatively and quantitatively). Results: There were no significant differences between the patients with FTCs and those with PTCs with respect to age and gender, and the internal composition, calcification and enhancement homogeneity of the tumor. However, the FTCs tend to show a larger size (32 mm vs. 15 mm; respectively, p < 0.001), a round to oval shape (52.9% vs. 14.8% respectively, p = 0.001), a well-defined smooth margin (58.8% vs. 14.8% respectively, p = 0.009), less extrathyroidal extension (11.8% vs. 51.9% respectively, p = 0.007) and less LN metastasis (0% vs. 29.6% respectively, p = 0.016) compared to that of the PTCs. Furthermore, the FTCs showed significantly stronger enhancement in the early phase (146.4±42.4 vs. 98.5±38.2 respectively, p < 0.001) and a greater decrement of the late enhancement (-44.6±25.2 vs. -18.7±27.9 respectively, p = 0.003) compared to that of the PTCs. Conclusion: FTCs had a tendency to be observed on neck CT as well-defined, smooth, round to oval nodules with strong early enhancement and a definite decrement of late enhancement as compared to the PTCs.