Value of CT in the diagnosis of papillary thyroid microcarcinoma

CHENG Jianming; ZHAN Songhua; ZHOU Jun; LU Fang; SONG Jingjing; CHENG Ruixin

Abstract：Objective To evaluate the CT features of papillary thyroid microcarcinoma (PTMC).Methods The CT findings of 54 cases with 73 histology-proven thyroid microcarcinomas were retrospectively reviewed.The reconstructed images of enhanced CT(slice thickness =0.625 mm) were analyzed in detail.Results Of the 73 lesions,56 lesions were shown and other 17 lesions not be found on CT.48 lesions were show homogeneous low density,7 lesions were shown isodensity and one was shown patchy calcification on non-enhanced CT.All tumors showed homogeneous low enhancement relative to normal thyroid tissue on post-contrast CT,without obvious necrosis area.43 lesions were shown pseudocapsule around the lesions and 23 tumors were shown thyroid edge interruption.Calcifications were revealed in 10 lesions,of which 7 were fine granular calcifications.Among the 17tumors that did not be shown up on CT,8 were complicated with Hashimoto's thyroiditis,4 were associated with nodular goiter and 1 was combined with ipsilateral thyroid adenoma.But the next other 4 lesions that's diameter was less than 0.3 cm were not complicated with other diseases.Conclusion Low density on non-enhanced CT,homogeneous low enhancement on post-contrast CT,pseudocapsule,thyroid edge interruption and fine granular calcification contribute to the diagnosis of papillary thyroid microcarcinoma.These CT features are more easier to be found on the reconstructed images of enhanced CT compared with thicker images.Some lesions that complicated with other thyroid diseases or tumors,diameter less than 0.3 cm are difficult to be detected on CT,which requirs adequate attention.