sup 18^F-EF5: A New PET Tracer for Imaging Hypoxia in Head and Neck Cancer

• Published in: The Journal of nuclear medicine (1978) Vol. 49; no. 12; p. 1944
• Main Authors: Komar, Gaber, Seppänen, Marko, Eskola, Olli, Lindholm, Paula, Grönroos, Tove J, sback, Sarita, Sipilä, Hannu, Evans, Sydney M, Solin, Olof, Minn, Heikki
• Format: Journal Article
• Language: English
• Published: New York Society of Nuclear Medicine 01.12.2008
• Subjects: Cancer; Head & neck cancer; Hospitals; Hypoxia; Methods; Otolaryngology; Radiation therapy; Radioactivity; Studies; Tomography; Tumors
• ISSN: 0161-5505; 1535-5667

The aim of this study was to evaluate 2-(2-nitro-^sup 1^H-imidazol1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide (EF5) labeled with ^sup 18^F-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 ^sup 18^F-EF5 PET/CT scan. On a separate day, ^sup 18^F-FDG PET/CT was performed to determine the metabolically active tumor volume. In 6 patients, dynamic ^sup 18^FEF5 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. ^sup 18^FEF5 uptake in tumors was compared with that in neck muscle, and the ^sup 18^F-EF5 findings were correlated with the ^sup 18^F-FDG PET/CT studies. Results: A total of 13 primary tumors and 5 lymph node metastases were evaluated for their uptake of ^sup 18^F-EF5. The median tumor-to-muscle ^sup 18^F-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 ^sup 18^F-EF5 to detect hypoxia in HNSCC is encouraging. Further development of ^sup 18^F-EF5 for eventual targeting of antihypoxia therapies is warranted. [PUBLICATION ABSTRACT]