Ma Jie-Tao, Han Cheng-Bo, Zheng Jia-He, Sun Hong-Zan, Zhang Shao-Min, Xin Jun, Guo Qi-Yong
Department of aRadiation Oncology bNuclear Medicine cRadiology, Shengjing Hospital of China Medical University, Shenyang dDepartment of Software Engineering, School of Computer Science and Engineering, Beifang University of Nationalities, Yinchuan, China.
Nucl Med Commun. 2017 Jul;38(7):642-649. doi: 10.1097/MNM.0000000000000687.
Accurate target delineation allows an increase in radiation dose to the target tumor while reducing damage to the surrounding normal tissue. However, there is currently no standard for evaluating volumes measured by different imaging modalities. The aim of this study is to evaluate the feasibility of contouring gross tumor volume (GTV) by PET/MRI in head and neck cancer, and to define an adaptive threshold level (aTL) for delineating the biological target volume (BTV).
Eighteen head and neck cancer patients underwent time of flight PET/MRI before chemoradiotherapy. Different GTVs of primary tumors and metastatic lymph nodes were manually contoured on MRI (GTVMRI), PET (GTVVIS), and fused PET/MRI (GTVFUS). An MRI-based GTV contour was substituted for the pathologic GTV. The percentile threshold boundary of the maximum standardized uptake value (SUVmax) for the BTV was determined when the volume of BTV approached that of GTVMRI.
All GTVs were highly correlated (all Pearson's r>0.85, all P<0.001). Tumor diameter strongly correlated with GTVs (r=0.7-0.8 for all lesions and primary tumor; r=0.8-0.9 for lymph node metastases). aTL and SUVmax were moderately correlated for all lesions (r=-0.692, P<0.001) and were strongly correlated for primary tumors (r=-0.866, P<0.001).
Delineating GTV on hybrid PET/MRIs is feasible, and aTL, the threshold boundary of BTV, was correlated inversely with the SUVmax.
精确的靶区勾画能够在增加靶区肿瘤辐射剂量的同时，减少对周围正常组织的损伤。然而，目前尚无评估不同成像模态所测量体积的标准。本研究旨在评估在头颈部癌中通过PET/MRI勾画大体肿瘤体积（GTV）的可行性，并确定用于勾画生物靶区（BTV）的自适应阈值水平（aTL）。
18名头颈部癌患者在放化疗前接受了飞行时间PET/MRI检查。在MRI（GTVMRI）、PET（GTVVIS）和融合的PET/MRI（GTVFUS）上手动勾画原发肿瘤和转移淋巴结的不同GTV。将基于MRI的GTV轮廓替代病理GTV。当BTV的体积接近GTVMRI的体积时，确定BTV最大标准化摄取值（SUVmax）的百分位数阈值边界。
所有GTV均高度相关（所有Pearson相关系数r>0.85，所有P<0.001）。肿瘤直径与GTV密切相关（所有病变和原发肿瘤的r=0.7-0.8；淋巴结转移的r=0.8-0.9）。所有病变的aTL与SUVmax中度相关（r=-0.692，P<0.001），原发肿瘤则高度相关（r=-0.866，P<0.001）。
在PET/MRI融合图像上勾画GTV是可行的，且BTV的阈值边界aTL与SUVmax呈负相关。
