Hybrid Imaging PET/CT with Application of 18F-Fluorothymidine in Patients with Head and Neck Carcinoma Undergoing Radiotherapy

Aim: To introduce the possible benefits of the positron-emission tomography (PET)Icomputed tomography (CT) with F-18-3'-deoxy-3'-fluorothymidine ( F-18-FLT) in patients with orofacial carcinomas and its impact to patient management. Materials and Methods: Thirty-six patients with orofacial squamous cell carcinomas underwent F-18-FLT-PET/CT during radiotherapy. Examinations were performed after administration of F-18-FLT (1.8 MBq/kg) including full-diagnostic CT. Analysis of the radiotherapy effect was performed with possible prospect of repeated and focused irradiation. Results: Complete absence of F-18-FLT uptake was found in 20 patients, thus complete response to radiotherapy was reported. Persistence of focal F-18-FLT uptake was observed in 16 patients; in 11 patients, the measured activity was only mild. In five patients, a higher level of F-18-FLT uptake was measured and additional irradiation was performed in defined regions. Repeated follow-up proved complete regression F-18-FLT uptake. Conclusion: It was possible to assess the effect of radiotherapy with the use of F-18-FLT-PET/CT and findings are suitable for radiation dose-escalation planning.