Abstract:Objective To investigate the correlation factors in delineating the gross tumor volume (GTV) of primary tumor in thoracic esophageal cancer based on the positron emission tomography-computed tomography (PET-CT)(thresholds of standardized uptake value or SUV ≥2.0 and ≥20% of maximum SUV or SUVmax) and the end-expiration (EE) phase of four-dimensional computed tomography (4DCT). Methods Twenty-two patients with thoracic esophageal cancer sequentially underwent 3DCT, 4DCT, and F-fluorodeoxyglucose PET-CT for thoracic localization. GTV50% was delineated by the EE phase of 4DCT. The internal GTVs based on PET-CT images (IGTVPET) were delineated by two thresholds:SUV ≥2.0 and ≥20% of SUVmax, and designated as IGTVPET2.0 and IGTVPET20%, respectively. The maximum transverse diameter of GTV50%, volume of GTV50%, the displacement in cranial-caudal (CC) direction, 3D motion vector, and SUVmax were obtained. Results The maximum transverse diameter of GTV50%, volume of GTV50%, the displacement in CC direction, and 3D motion vector showed no significant correlations with the volume ratio (VR) of IGTVPET20% or IGTVPET2.0 to GTV50%(P=0.055- 0.932), but showed significant correlations with the conformity index (CI) between IGTVPET20% or IGTVPET2.0 and GTV50%(P=0.005- 0.033). Significant correlations were observed between the VR and CI of IGTVPET20% to GTV50% and SUVmax(P=0.001 and 0.016, respectively). Conclusions IGTV based on PET-CT images cannot objectively and accurately reflect the changes in spatial position and motion of the tumor, and the selection of a single SUV threshold is unreliable. To determine the primary tumor target in esophageal cancer, the IGTV based on 4DCT should be used to correct the boundary and position of IGTV constructed based on PET-CT.
Guo Yanluan,Li Jianbin,Li Fengxiang et al. Analysis of correlation between GTVs delineated based on SUVs of PET-CT and EE phase of 4DCT in thoracic esophageal cancer[J]. Chinese Journal of Radiation Oncology, 2015, 24(2): 121-125.
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