Radiother Oncol：PET能帮助确定口咽部肿瘤患者放疗靶区和预测患者预后

肿瘤亚型的空间结构关系到放疗靶区的确定和对患者结局的预测。Matthew J等旨在调查在口咽部肿瘤的患者中，通过三维成像PET影像数据确定肿瘤亚型和肿瘤代谢、增生和乏氧状态的关系。来自美国威斯康辛大学的研究者就上述问题进行了研究并将结果发表在Radiother Oncol 10月的期刊上。

口咽部肿瘤患者接受18F-氟去氧葡萄糖（FDG） PET/CT、18-氟三氯甲烷（FLT） PET/CT和61Cu-二乙酰基- (甲基缩氨基硫脲)(Cu-ATSM) PET/CT检查。计算所有模态下标准摄取值。采用基于三维成像的方法计算肿瘤区域内Pearson相关系数。此外，也定量评价了图像分割、图像配准技术、噪音和R分割的敏感性。

FDG PET和FLT PET影像的相关性最高，而Cu-ATSM PET的异质性最好。在所测试的参数中，图像配准技术的敏感性最好。图像噪音和图像重建也能定量评价相关性。大体肿瘤体积、扩展大体肿瘤体积或CTV之间无显着地定量差异。

三维成像联系能代表肿瘤亚型靶区的空间结构。这些结果能提示肿瘤靶区的确定以及在治疗前通过确定肿瘤亚型分布帮助预测患者的临床预后。

DOI:10.1016/j.radonc.2012.09.012
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Correlation of PET images of metabolism, proliferation and hypoxia to characterize tumor phenotype in patients with cancer of the oropharynx

Matthew J. Nyflot, , Paul M. Harari, Stephen Yip, Scott B. Perlman, Robert Jeraj

Spatial organization of tumor phenotype is of great interest to radiotherapy target definition and outcome prediction. We characterized tumor phenotype in patients with cancers of the oropharynx through voxel-based correlation of PET images of metabolism, proliferation, and hypoxia. Methods Patients with oropharyngeal cancer received 18F-fluorodeoxyglucose (FDG) PET/CT, 18F-fluorothymidine (FLT) PET/CT, and 61Cu-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) PET/CT. Images were co-registered and standardized uptake values (SUV) were calculated for all modalities. Voxel-based correlation was evaluated with Pearson’s correlation coefficient in tumor regions. Additionally, sensitivity studies were performed to quantify the effects of image segmentation, registration, noise, and segmentation on R. Results On average, FDG PET and FLT PET images were most highly correlated (RFDG:FLT = 0.76, range 0.53–0.85), while Cu-ATSM PET showed greater heterogeneity in correlation to other tracers (RFDG:Cu-ATSM = 0.64, range 0.51–0.79; RFLT:Cu-ATSM = 0.61, range 0.21–0.80). Of the tested parameters, correlation was most sensitive to image registration. Misregistration of one voxel lead to ΔRFDG = 0.25, ΔRFLT = 0.39, and ΔRCu-ATSM = 0.27. Image noise and reconstruction also had quantitative effects on correlation. No significant quantitative differences were found between GTV, expanded GTV, or CTV regions. Conclusions Voxel-based correlation represents a first step into understanding spatial organization of tumor phenotype. These results have implications for radiotherapy target definition and provide a framework to test outcome prediction based on pretherapy distribution of phenotype.