PET/CT在食管癌肿瘤区勾画中的应用

Application of PET/CT in Delineation of Gross Target Volume for Esophageal Cancer

目的应用^(18)F脱氧葡萄糖(^(18)F-FDG)正电子发射计算机断层扫描(PET/CT)图像勾画食管癌原发肿瘤区(GTV),探讨不同方法勾画的准确性。方法选取10例未手术的胸段食管癌患者的PET/CT,分别采用标准摄取值(SUV)2.5、最大SUV(SUV_(max))的40%、PET-edge以及医生通过视觉观察法手动勾画四种方法勾画食管癌GTV,分别命名为GTV2.5、GTV40%、GTV_(edge)以及GTV_(man)。以GTV_(man)作为标准,采用GTV的体积、Hausdorff距离(HD)以及形状相似性指数(DSC)3个指标评价自动识别与手动勾画的几何学一致性。结果与GTV_(man)体积相比,所有患者的GTV2.5均偏大(24.90±7.61)%,所有患者的GTV40%均偏小(26.81±9.63)%,GTV_(edge)有的偏大有的偏小,差异为(12.51±14.28)%(均值使用偏差比率的绝对值)。三种勾画方式的DSC分别为0.82、0.78、0.85,GTV40%与GTV_(edge)勾画的DSC有统计学差异(P=0.015),其余对比无统计学差异。HD分别为6.87mm、6.92mm、6.25mm,差异均无统计学意义。结论使用2.5的阈值以及PET-edge自动识别可用于PET/CT勾画食管癌GTV,推荐二者结合使用指导GTV的勾画,满足临床应用的同时,提高勾画的准确度和效率。

Objective To explore the accuracy of different methods for delineating the gross tumor volumes(GTV)of the primary esophageal cancer using PET/CT images.Methods PET/CT images of 10 patients with thoracic esophageal cancer without surgery were selected.The GVTs of esophageal cancer were delineated by standard uptake value(SUV)2.5,maximum SUV(SUV_(max))40%,PET-edge,and manual delineation by visual,named GTV2.5,GTV40%,GTV_(edge)and GTV_(man)respectively.Using GTV_(man)as the standard,three indexes:volume of GTV,distances of Hausdorff(HD)and dice similarity coefficient(DSC)were used to evaluate the geometric consistency between automatic identifications and manual delineations.Results Compared with the volume of GTV_(man),GTV2.5 were larger in all patients(24.90±7.61)%,GTV40%were smaller in all patients(26.81±9.63)%,and GTV_(edge)were larger in some patients and smaller in others(12.51±14.28)%(absolute value of the deviation ratio of the mean).The DSC of the three delineation methods were 0.82,0.78,0.85,which delineated by GTV40%and GTV_(edge)were statistically different(P=0.015),and the rest have no statistically differences.HD was 6.87mm,6.92mm and 6.25mm,the differences were not statistically significant.Conclusion Standard uptake value(SUV)2.5 and automatic PET-edge recognition can be used to delineate esophageal cancer GTV in PET/CT images.It is recommended that the two methods should be combined to guide the delineation of GTV,which can meet the needs of clinical application,and improve the accuracy and efficiency of delineation.