RT Journal Article SR Electronic T1 18F-EF5: A New PET Tracer for Imaging Hypoxia in Head and Neck Cancer JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1944 OP 1951 DO 10.2967/jnumed.108.053785 VO 49 IS 12 A1 Gaber Komar A1 Marko Seppänen A1 Olli Eskola A1 Paula Lindholm A1 Tove J. Grönroos A1 Sarita Forsback A1 Hannu Sipilä A1 Sydney M. Evans A1 Olof Solin A1 Heikki Minn YR 2008 UL http://jnm.snmjournals.org/content/49/12/1944.abstract AB The aim of this study was to evaluate 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide (EF5) labeled with 18F-fluorine to image hypoxia in patients with squamous cell carcinoma of the head and neck (HNSCC). Methods: Fifteen patients with HNSCC were studied. Measurement of tumor blood flow was followed by an 18F-EF5 PET/CT scan. On a separate day, 18F-FDG PET/CT was performed to determine the metabolically active tumor volume. In 6 patients, dynamic 18F-EF5 images of the head and neck area were acquired, followed by static images acquired at 1, 2, and 3 h after injection. In the remaining 9 patients, only static images were obtained. 18F-EF5 uptake in tumors was compared with that in neck muscle, and the 18F-EF5 findings were correlated with the 18F-FDG PET/CT studies. Results: A total of 13 primary tumors and 5 lymph node metastases were evaluated for their uptake of 18F-EF5. The median tumor-to-muscle 18F-EF5 uptake ratio (T/M) increased over time and was 1.38 (range, 1.1–3.2) 3 h after tracer injection. The median blood flow in tumors was 36.7 mL/100 g/min (range, 23.3–78.6 mL/100 g/min). Voxel-by-voxel analysis of coregistered blood flow and 18F-EF5 images revealed a distinct pattern, resulting in a T/M of 1.5 at 3 h to be chosen as a cutoff for clinically significant hypoxia. Fourteen of 18 tumors (78%) had subvolumes within the metabolically active tumor volumes with T/M greater than or equal to 1.5. Conclusion: On the basis of these data, the potential of 18F-EF5 to detect hypoxia in HNSCC is encouraging. Further development of 18F-EF5 for eventual targeting of antihypoxia therapies is warranted.