The value of MSCT in differentiating low-or high-risk thymomas and thymic carcinomas with maximum diameter equal or less than 3 cm / 实用放射学杂志

ABSTRACT

Objective To evaluate the diagnostic value of MSCT in the differentiation of thymic epithelial tumours (TET)with the maximum diameter equal or less than 3 cm.Methods A retrospective analysis of pathological and imaging data of 56 patients with pathologically confirmed TET with the maximum diameter equal or less than 3 cm was performed.According to the 2004 WHO classification,56 TETs were classified as low-risk thymomas(types A/AB/B1),high-risk thymomas (types B2/B3)and thymic carcinomas (type C).The CT manifestations of TET in each group,including shape of tumor,tumor edge (smooth or spiculate protuberance), presence of small nodule around tumor,enhancement degree,pleura invasion and fat space around tumor,were analyzed retrospectively.The differences in the CT manifestations among three types were compared using chi-square test.If the sample number was too small, Fisher 's exact test was used.Results Compared with high-risk thymomas (23 cases)and thymic carcinomas (6 cases),regular round shape was more often observed in low-risk thymomas (27 cases)(χ2 =73,P <0.001;χ2 =116,P <0.001)and the mediastinum-lung interface was more likely to bulge (χ2 = 3.41,P =0.046;χ2 =7.39,P =0.01).Blurred edge,spiculate protuberance and pleural invasion and so on were significantly more common in high-risk thymomas and thymic carcinomas (P <0.001)and they were the most common in thymic carcinomas (χ2 =11.5,P =0.009).There was a significant difference between type B2 thymomas and thymic carcinomas (χ2 =31.52, P <0.001),however there was no significant difference between type B3 thymomas and thymic carcinomas (χ2 =6.96,P =0.07). Conclusion MSCT can accurately show the shape of tumor,tumor edge,presence of small nodule around tumor,enhancement degree,pleura invasion,which can predict the histologic type of thymomas and also can provide information for preoperative diagnosis and prognosis evaluation.