甲状腺微小乳头状癌的CT诊断价值分析

Value of CT in the diagnosis of papillary thyroid microcarcinoma

目的探讨甲状腺微小乳头状癌的CT征象特点。方法回顾性分析54例共73枚经手术病理证实的甲状腺微小乳头状癌的CT平扫和增强资料,其中CT增强的薄层重建图像(重建层厚=0.625mm)被重点观察、分析。结果73枚病灶中,56枚在CT上显示,17枚未显示。56枚中CT平扫48枚呈低密度,7枚呈等密度,1枚呈单纯斑片状钙化。增强CT所有瘤体呈均匀性低强化,无坏死、囊变。43枚显示"假包膜征"。23枚显示"甲状腺边缘中断征"。10枚伴有钙化,其中7枚为细颗粒状钙化。CT未显示的17枚中,8枚合并桥本氏甲状腺炎,4枚合并结节性甲状腺肿,1枚合并同侧甲状腺腺瘤,另4枚(直径≤0.3cm)未合并其它疾病。结论平扫低密度、均匀性相对低强化、假包膜征、甲状腺边缘中断征、细颗粒状钙化是甲状腺微小乳头状癌较为特征的CT征象,增强CT的薄层重建图像有助于上述征象的显示。对于合并其它甲状腺疾病或瘤体直径≤0.3cm的病灶,CT难以显示,需引起注意。

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-con- trast CT, without obvious necrosis area. 43 lesions were shown pseudocapsule around the lesions and 23 tumors were shown thy- roid edge interruption. Calcifications were revealed in 10 lesions, of which 7 were fine granular calcifications. Among the 17 tumors that did not be shown up on CT, 8 were complicated with Hashimotog thyroiditis, 4 were associated with nodular goiter and 1 was combined with ipsilateral thyroid adenoma. But the next other 4 lesions thatg 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, pseadocapsule, thyroid edge interruption and fine granular calcification contribute to the diagnosis of papillary thyroid microcarci- noma. 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.