Di Perri Dario, Lee John A, Bol Anne, Hanin François-Xavier, Janssens Guillaume, Labar Daniel, Robert Annie, Sterpin Edmond, Geets Xavier
a Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain , Brussels , Belgium.
b Department of Radiation Oncology , Cliniques universitaires Saint-Luc , Brussels , Belgium.
Acta Oncol. 2017 Apr;56(4):516-524. doi: 10.1080/0284186X.2017.1287943. Epub 2017 Feb 22.
Dose painting (DP) aims to improve radiation therapy (RT) outcome by targeting radioresistant tumour regions identified through functional imaging, e.g., positron emission tomography (PET). Importantly, the expected benefit of DP relies on the ability of PET imaging to identify tumour areas which could be consistently targeted throughout the treatment. In this study, we analysed the spatial stability of two potential DP targets in lung cancer patients undergoing RT: the tumour burden surrogate [F]fluorodeoxyglucose (FDG) and the hypoxia surrogate [F]fluoroazomycin arabinoside (FAZA).
Thirteen patients with unresectable lung tumours underwent FDG and FAZA 4D-PET/CT before (pre), and during the second (w2) and third (w3) weeks of RT. All PET/CT were reconstructed in their time-averaged midposition (MidP) for further analysis. The metabolic tumour volume (MTV: FDG standardised uptake value (SUV) > 50% SUV) and the hypoxic volume (HV: FAZA SUV >1.4) were delineated within the gross tumour volume (GTV). The stability of FDG and FAZA PET uptake distributions during RT was subsequently assessed through volume-overlap analysis and voxel-based correlation analysis.
The volume-overlap analysis yielded median overlapping fraction (OF) of 0.86 between MTV and MTV and 0.82 between MTV and MTV. In patients with a detectable HV, median OF was 0.82 between HV and HV and 0.90 between HV and HV. The voxel-based correlation analysis yielded median Spearman's correlation coefficient (r) of 0.87 between FDG and FDG and 0.83 between FDG and FDG. Median r was 0.78 between FAZA and FAZA and 0.79 between FAZA and FAZA.
FDG and FAZA PET uptake distributions were spatially stable during the 3 first weeks of RT in patients with unresectable lung cancer, both based on volume- and voxel-based indicators. This might allow for a consistent targeting of high FDG or FAZA PET uptake regions as part of a DP strategy.
剂量描绘（DP）旨在通过靶向通过功能成像（例如正电子发射断层扫描（PET））识别出的放射抗性肿瘤区域来改善放射治疗（RT）的效果。重要的是，DP的预期益处依赖于PET成像识别在整个治疗过程中可始终靶向的肿瘤区域的能力。在本研究中，我们分析了接受RT的肺癌患者中两个潜在DP靶点的空间稳定性：肿瘤负荷替代物[F]氟脱氧葡萄糖（FDG）和缺氧替代物[F]氟阿糖胞苷（FAZA）。
13例不可切除肺肿瘤患者在RT前（pre）、RT第二周（w2）和第三周（w3）接受了FDG和FAZA 4D-PET/CT检查。所有PET/CT均在其时间平均中间位置（MidP）重建以进行进一步分析。在大体肿瘤体积（GTV）内勾勒出代谢肿瘤体积（MTV：FDG标准化摄取值（SUV）>50%SUV）和缺氧体积（HV：FAZA SUV>1.4）。随后通过体积重叠分析和基于体素的相关性分析评估RT期间FDG和FAZA PET摄取分布的稳定性。
体积重叠分析得出MTV与MTV之间的中位重叠分数（OF）为0.86，MTV与MTV之间为0.82。在可检测到HV的患者中，HV与HV之间的中位OF为0.82，HV与HV之间为0.90。基于体素的相关性分析得出FDG与FDG之间的中位斯皮尔曼相关系数（r）为0.87，FDG与FDG之间为0.83。FAZA与FAZA之间的中位r为0.78，FAZA与FAZA之间为0.79。
基于体积和体素的指标，不可切除肺癌患者在RT的前3周内，FDG和FAZA PET摄取分布在空间上是稳定的。这可能允许将高FDG或FAZA PET摄取区域作为DP策略的一部分进行一致的靶向。
