Repeatability of hypoxia PET imaging using [(18)F]HX4 in lung and head and neck cancer patients: a prospective multicenter trial

PURPOSE: Hypoxia is an important factor influencing tumor progression and treatment efficacy. The aim of this study was to investigate the repeatability of hypoxia PET imaging with [(18)F]HX4 in patients with head and neck and lung cancer. METHODS: Nine patients with lung cancer and ten with head and neck cancer were included in the analysis (NCT01075399). Two sequential pretreatment [(18)F]HX4 PET/CT scans were acquired within 1 week. The maximal and mean standardized uptake values (SUV(max) and SUV(mean)) were defined and the tumor-to-background ratios (TBR) were calculated. In addition, hypoxic volumes were determined as the volume of the tumor with a TBR >1.2 (HV(1.2)). Bland Altman analysis of the uptake parameters was performed and coefficients of repeatability were calculated. To evaluate the spatial repeatability of the uptake, the PET/CT images were registered and a voxel-wise comparison of the uptake was performed, providing a correlation coefficient. RESULTS: All parameters of [(18)F]HX4 uptake were significantly correlated between scans: SUV(max) (r = 0.958, p < 0.001), SUV(mean) (r = 0.946, p < 0.001), TBR(max) (r = 0.962, p < 0.001) and HV(1.2) (r = 0.995, p < 0.001). The relative coefficients of repeatability were 15 % (SUV(mean)), 17 % (SUV(max)) and 17 % (TBR(max)). Voxel-wise analysis of the spatial uptake pattern within the tumors provided an average correlation of 0.65 ± 0.14. CONCLUSION: Repeated hypoxia PET scans with [(18)F]HX4 provide reproducible and spatially stable results in patients with head and neck cancer and patients with lung cancer. [(18)F]HX4 PET imaging can be used to assess the hypoxic status of tumors and has the potential to aid hypoxia-targeted treatments. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00259-015-3100-z) contains supplementary material, which is available to authorized users.