MRI对恶性胸腺瘤的诊断价值及与其组织病理学分型的相关性研究

目的探讨恶性胸腺瘤MRI表现及与其组织病理学分型的相关性。方法回顾性分析16例经穿刺、手术病理检查证实为恶性胸腺瘤的MR影像特征及其病理学分型。结果 16例恶性胸腺瘤中侵袭性胸腺瘤12例,胸腺癌4例;肿块直径>10 cm者8例;5～10 cm者6例;<5 cm者2例;包膜完整1例,包膜不完整15例;轮廓不规则或分叶状13例,轮廓规则3例;侵犯胸膜14例,侵犯心包12例,侵犯大血管6例;远处转移2例;肿块实质信号不均匀14例,实质信号均匀2例。结论恶性胸腺瘤大多包膜不完整、轮廓不规则或分叶状、实质信号不均匀、多数可侵犯胸膜、心包或发生远处转移;肿块直径越大,恶性胸腺瘤可能性越大;MRI检查难以区分恶性胸腺瘤Ⅰ型(侵袭性胸腺瘤)与恶性胸腺瘤Ⅱ型(胸腺癌)。

The Study of Relationship between MRI Features and Histopathologic Type of Malignant Thymoma

Objective To explore the relationship between MRI features and histopathologic type of malignant thymoma.Methods Retrospective analysis of 16 cases by puncture,surgical pathological examination confirmed the MR imaging features of malignant thymoma and its pathological types.Results Of the 16 cases,the numbers of invasive thymoma and thymic carcinoma were 12 and 4,respectively.There were 8 cases with more than 10 cm in tumor diameter,6 cases were between 5 and 10 cm in diameter,2 cases were less than 5 cm in diameter.A case had intact membrane,but 15 cases were without intact membrane.13 cases had a higher prevalence of irregular or lobular contours,while 3 cases had regular contours.The numbers of pleural invasion,pericardial invasion,main vessels invasion and distant metastasis were 14,12,6 and 2,respectively.There were 14 cases with heterogeneous signals of tumor parenchyma and 2 cases with homogeneous signals of tumor parenchyma.Conclusion Incomplete membrane with irregular or lobular contours,more than 10 cm in diameter with heterogeneous signals of tumor parenchyma,pleural and pericardial invasion with distant metastasis are all highly suggestive of malignant thymoma.Malignant thymoma is also with longer diameter than other tumors.MRI is of limited value,however,in differentiating type 1（invasive thymoma） from type 2（thymic carcinoma） malignant thymoma.