^(18)F-FDG PET/CT代谢参数预测胸腺上皮肿瘤恶性程度

^(18)F-FDG PET/CT metabolic parameters for predicting malignancy degree of thymus epithelial tumors

目的观察^(18)F-FDG PET/CT代谢参数对预测胸腺上皮肿瘤(TET)恶性程度的价值。方法回顾性分析95例经病理诊断的TET患者,根据病理结果进行组织学分型(低危型胸腺瘤、高危型胸腺瘤、胸腺癌)及临床分期(Ⅰ~Ⅳ期)。基于^(18)F-FDG PET/CT获取原发灶最大标准摄取值(SUV_(max))、峰值标准摄取值(SUV_(peak))、原发灶SUV_(max)与纵隔血池平均标准摄取值的比值,即靶区本底比值(TBR),分别以SUV=2.5及40%SUV_(max)为阈值,获得病灶糖酵解总量(TLG_(2.5)、TLG_(40%))及肿瘤代谢体积(MTV_(2.5)、MTV_(40%))。比较不同类型及临床分期TET各代谢参数的差异。针对两两比较差异均有统计学意义的代谢参数绘制受试者工作特征(ROC)曲线,计算曲线下面积(AUC),评估其预测不同组织学分型TET的效能。结果95例中,27例低危型胸腺瘤、15例高危型胸腺瘤、53例胸腺癌;临床分期Ⅰ期28例、Ⅱ期8例、Ⅲ期12例、Ⅳ期47例。不同类型TET间SUV_(max)、SUV_(peak)及TBR差异均有统计学意义(P均<0.05),高危型胸腺瘤及胸腺癌TLG_(2.5)和MTV_(2.5)均高于低危型胸腺瘤(P均<0.05),胸腺癌TLG_(40%)高于低危型胸腺瘤(P<0.05);其他代谢参数差异均无统计学意义(P均>0.05)。临床Ⅳ期TET的SUV_(max)、SUV_(peak)、TBR、TLG_(2.5)、TLG_(40%)、MTV_(2.5)均高于Ⅰ期(P均<0.05),Ⅲ期TET的TLG_(2.5)高于Ⅰ期(P<0.05),不同临床分期TET其余代谢参数差异均无统计学意义(P均>0.05)。以SUV_(max)、SUV_(peak)及TBR预测低危型与高危型胸腺瘤的AUC分别为0.857、0.840及0.857,预测高危型胸腺瘤与胸腺癌的AUC分别为0.769、0.758及0.755。结论^(18)F-FDG PET/CT代谢参数可有效预测TET恶性程度。

Objective To investigate the value of ^(18)F-FDG PET/CT metabolic parameters for predicting malignancy degree of thymus epithelial tumors(TET).Methods Data of 95 TET patients confirmed by pathology were retrospectively analyzed.The histological types(low-risk thymoma,high-risk thymoma,thymic cancer)and clinical stages(stageⅠ—Ⅳ)of TET were evaluated according to pathological findings.Based on ^(18)F-FDG PET/CT,the maximum standard uptake value(SUV_(max))and the peak standard uptake value(SUV_(peak))of origical tomors,the ratio of SUV_(max) to the mean standard uptake value of mediastinal blood pool,i.e.target-to-background ratio(TBR)were calculated.Taking SUV=2.5 and 40%SUV_(max) as thresholds,the total lesion glycolysis(TLG_(2.5),TLG_(40%))and metabolic tumor volume(MTV_(2.5),MTV_(40%))were obtained,respectively.Metabolic parameters of TET were compared among different histological types and clinical stages.Receiver operating characteristic(ROC)curves of the above metabolic parameters being significantly different in pairwise comparisons were drawn,and the area under the curve(AUC)were calculated to evaluate the efficacy for predicting for histological type of TET.Results Among 95 cases,low-risk thymoma,high-risk thymoma and thymic cancer were found in 27,15 and 53 cases,including 28 cases of stageⅠ,8 cases of stageⅡ,12 cases of stageⅢand 47 cases of stageⅣ.Significant differences of SUV_(max),SUV_(peak) and TBR were among different histological types TET(all P<0.05).TLG_(2.5) and MTV_(2.5) of high-risk thymoma and thymic cancer were higher than those of low-risk thymoma(all P<0.05),and TLG 40%of thymic cancer was higher than that of low-risk thymoma(P<0.05).No significant difference of other metabolic parameters was found(all P>0.05).SUV_(max),SUV_(peak),TBR,TLG_(2.5),TLG_(40%) and MTV_(2.5) of stageⅣTET were higher than those of stageⅠTET(all P<0.05),and TLG_(2.5) of stageⅢTET was higher than that of stageⅠTET(P<0.05).There was no significant difference of other metabolic parameters among TET among different clinical stages(all P>0.05).AUC of SUV_(max),SUV_(peak) and TBR for predicting low-risk and high-risk thymoma was 0.857,0.840 and 0.857,for predicting high-risk thymoma and thymic cancer was 0.769,0.758 and 0.755,respectively.Conclusion ^(18)F-FDG PET/CT metabolic parameters could effectively predict malignancy degree of TET.