Objectives: To examine the potential of pre-treatment dual time point [18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) as a tool for improving the assessment of head and neck cancer. Two main areas were investigated: (a) optimum time to start FDG scanning post-injection and (b) potential of SUV obtained from dual time point scanning as a prognostic indicator of survival.
Methods: Twelve patients with advanced head and neck cancer were prospectively studied. Each patient was scanned using a Siemen's Ecat Exact-47 PET scanner at 1 h and 2 h post-injection. Maximum tumour uptake (SUVt) and ratio of maximum tumour/normal tissue uptake (SUVt/n) were recorded. The optimal time to initiate scanning was investigated by comparing SUVt and SUVt/n with the decision made by two experienced observers as to which scan they preferred to report from, given the choice of the 1 h and 2 h scan in each patient.
Results: A significant difference between 1 h and 2 h SUVt (P<0.004, paired t-test) and between 1 h and 2 h SUVt/n (P<0.0003, paired t-test) was observed. All 2 h SUVt and SUVt/n were greater in magnitude than their respective 1 h SUVt and SUVt/n counterparts. The two observers reported an identical number of lesions from the 1 h and 2 h scans but preferred the 2 h data.
Conclusions: Tumour stage and the percentage difference in 1 h and 2 h SUVt showed potential as prognostic indicators of long-term survival.