RT Journal Article SR Electronic T1 PET Imaging of Tumor Hypoxia Using 18F-Fluoroazomycin Arabinoside in Stage III–IV Non–Small Cell Lung Cancer Patients JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1175 OP 1180 DO 10.2967/jnumed.112.115014 VO 54 IS 8 A1 Vikram R. Bollineni A1 Gerald S.M.A. Kerner A1 Jan Pruim A1 Roel J.H.M. Steenbakkers A1 Erwin M. Wiegman A1 Michel J.B. Koole A1 Eleonore H. de Groot A1 Antoon T.M. Willemsen A1 Gert Luurtsema A1 Joachim Widder A1 Harry J.M. Groen A1 Johannes A. Langendijk YR 2013 UL http://jnm.snmjournals.org/content/54/8/1175.abstract AB Tumor hypoxia hampers the efficacy of radiotherapy because of its increased resistance to ionizing radiation. The aim of the present study was to estimate the potential added clinical value of the specific hypoxia tracer 18F-fluoroazomycin arabinoside (18F-FAZA) over commonly used 18F-FDG in the treatment of advanced-stage non–small cell lung cancer (NSCLC). Methods: Eleven patients with stage III or stage IV NSCLC underwent 18F-FDG and 18F-FAZA PET before chemoradiotherapy. The maximum standardized uptake value (SUVmax) was used to depict 18F-FDG uptake, and the tumor-to-background (T/B) ratio and tumor fractional hypoxic volume (FHV) were used to quantify hypoxia. The spatial correlation between 18F-FDG and 18F-FAZA uptake values was investigated using voxel-based analysis. Partial-volume correction was applied. Results: All 11 patients showed clear uptake of 18F-FAZA in the primary tumor. However, different patterns of 18F-FDG and 18F-FAZA uptake distributions were observed and varied widely among different tumors. No significant correlation was observed between 18F-FDG SUVmax and 18F-FAZA T/B ratio (P = 0.055). The median FHV of 1.4 was 48.4% (range, 5.0–91.5). A significant positive correlation was found between the 18F-FAZA T/B ratio and FHV of 1.4 (P < 0.001). There was no correlation between the lesion size and FHV or between the 18F-FDG SUVmax and FHV. The pattern of tumoral 18F-FDG uptake was rather homogeneous, whereas 18F-FAZA uptake was more heterogeneous, suggesting that 18F-FAZA identifies hypoxic areas within metabolically active areas of tumor. A significant correlation between 18F-FDG SUVmax and lesion size (P = 0.002) was observed. Conclusion: 18F-FAZA PET imaging is able to detect heterogeneous distributions of hypoxic subvolumes out of homogeneous 18F-FDG background in a clinical setting. Therefore, 18F-FAZA might be considered a tool for guiding dose escalation to the hypoxic fraction of the tumor.