^(18)F-FDG符合线路SPECT/CT显像对前纵隔肿瘤良恶性的诊断价值

Role of ^(18)F-FDG coincidence SPECT/CT in the differenting malignant tumor from benign lesion of anterior medialstinal masses

目的观察前纵隔肿瘤18F-FDG符合线路SPECT/CT显像的特点,探讨其对前纵隔肿瘤良恶性鉴别诊断的价值。方法回顾分析2009年7月~2013年12月本院病理证实的20例前纵隔肿瘤患者的影像资料,所有患者均有完整的治疗前18F-FDG符合线路图像及CT资料。记录肿块最大径、目测分级、术后病理及胸腺肿瘤的Masaoka分期。结果前纵隔肿瘤平均最大径为6.61cm(3.0~14.0cm)。前纵隔肿瘤术后病理证实:霍奇金淋巴瘤5例,胸腺癌6例,胸腺瘤2例,其他良性病变7例(囊性畸胎瘤3例,心包囊肿2例,脂肪瘤1例,巨淋巴结增生症1例)。病变目测分级0级4例,1级3例,2级2例,3级11例。肿块最大径与目测分级的相关系数r=0.467,为低度相关。良性病变组目测分级低于霍奇金淋巴瘤及胸腺癌(P<0.01),良性病变与胸腺瘤的目测分级无明显差异(P=0.21),胸腺癌目测分级高于胸腺瘤(P=0.03),胸腺癌与淋巴瘤目测分级无明显差异(P=0.36)。以目测放射性摄取低于纵隔为标准鉴别前纵隔肿瘤良恶性的准确率为95%,仅1例假阳性病例为巨淋巴结增生症。目测分级1级的胸腺瘤为MasaokaⅠ期胸腺瘤。结论18F-FDG符合线路显像鉴别前纵隔肿瘤良恶性的准确率较高,当前纵隔肿瘤FDG摄取程度低于纵隔时提示为良性病变或可以直接手术切除的低危胸腺瘤;胸腺癌与淋巴瘤均为高FDG摄取病变,因此当前纵隔病变FDG摄取程度明显高于纵隔,结合CT鉴别胸腺癌与淋巴瘤有困难时,需要穿刺活检以取得病理诊断指导治疗。

Objective To explore the usefulness of 18F-FDG coincidence SPECT/CT in differentiating malignant tumor from benign lesion of anterior medialstinal masses. Methods We retrospectively reviewed the imagine findings of 20 patients with histopathologically proved anterior medialstinal masses. All the patients had 18F_FDG coincidence SPECT/CT and the CT imagines before treatment. The maximal transverse diameter at CT, visual graded of 18 F-FDG uptake, histolo- gy and Masaoka staging for thymomas were recorded. Results The mean diameter of the mases was 6.61 cm （3-14.0 cm）. According to the histopathological results, patients were divided into four groups, 5 cases of Hodgkin＇s lymphomas, 6 cases of thymic carcinoma, 2 cases of thymoma and 7 cases of benign lesions （3 cases of cysitc teratoma, 2 cases of peri- cardiac cyst, 1 case of lipoma, 1 case of castleman＇s disease） . The uptake of 18 F-FDG was graded by visual method. 4 lesions were graded as 0, 3 lesions were graded 1, 2 lesions were graded as 2 and 11 lesions graded as 3. The correlation between the maximal transverse diameter and the visual grade was low （ r = 0. 467）. The visual grade of Benign lesion is lower than Hodgkin＇s lymphoma or thymic carcinoma （ P d0.01 ）. There is no difference of visual grade between benign lesion and thymoma （ P =0.21）. The visual grade of thymic carcinoma is higher than thymoma （ P =0.03）. There is no difference of the visual grade between thymic carcinoma and Hodgkin＇s lymphoma （ P =0.36）. Accuracy is 95 % for taking visual grade 2 as the cut-off to differentiate malignant tumor from benign . Only 1 false positive lesion was Castleman＇s disease. The thymoma, which was visual graded as 1, was masaoka stage I.Conclusion The accuracy of 18 F-FDG co- incidence SPECT/CT in differentiating malignant tumor from benign lesion of anterior medialstinal masses was high. Visual grade as 0 or 1 indicates the mass is benign or upfront surgical resection thymoma. The FDG uptake of thymic carcinoma and lymphoma is high. A biopsy might be obtained when the mass is visual graded as 3 and difficult to differentiate between lymphoma and thymic carcinoma.