Tumour hypoxia imaging with [18F]FAZA PET in head and neck cancer patients:: a pilot study

Purpose Hypoxia is an important negative prognostic factor for radiation treatment of head and neck cancer. This study was performed to evaluate the feasibility of use of F-18-labelled fluoroazomycin arabinoside ([F-18]FAZA) for clinical PET imaging of tumour hypoxia. Methods Eleven patients (age 59.6 +/- 9 years) with untreated advanced head and neck cancer were included. After injection of approximately 300 MBq of [F-18]FAZA, a dynamic sequence up to 60 min was acquired on an ECAT HR+ PET scanner. In addition, approximately 2 and 4 h p.i., static whole-body PET (n=5) or PET/CT (n=6) imaging was performed. PET data were reconstructed iteratively (OSEM) and fused with CT images (either an external CT or the CT of integrated PET/CT). Standardised uptake values (SUVs) and tumour-to-muscle (T/M) ratios were calculated in tumour and normal tissues. Also, the tumour volume displaying a T/M ratio > 1.5 was determined. Results Within the first 60 min of the dynamic sequence, the T/M ratio generally decreased, while generally increasing at later time points. At 2 h p.i., the tumour SUVmax and SUVmean were found to be 2.3 +/- 0.5 (range 1.5-3.4) and 1.4 +/- 0.3 (range 1.0-2.1), respectively. The mean T/M ratio at 2 h p.i. was 2.0 +/- 0.3 (range 1.6-2.4). The tumour volume displaying a T/M ratio above 1.5 was highly variable. At 2 h p.i., [F-18]FAZA organ distribution was determined as follows: kidney > gallbladder > liver > tumour > muscle > bone > brain > lung. Conclusion [F-18]FAZA PET imaging appears feasible in head and neck cancer patients, and the achieved image quality is adequate for clinical purposes. Based on our initial results, [F-18]FAZA warrants further evaluation as a hypoxia PET tracer for imaging of cancer.