18F-FLT PET/CT imaging in a Wister rabbit inflammation model

The aim of the present study was to determine the tumour specificity of the newly developed nucleoside metabolic positron emission tomography (PET) tracer, 3'-deoxy-3'-18F-fluorothymidine (18F-FLT). Using 18F-FLT PET imaging, DNA synthesis and cell proliferation were detected in Staphylococcus aureus (S. aureus) abscess and calcium sulphate models in Wister rabbits. A total of eight rabbits were implanted with S. aureus in the left tibia to induce an inflammatory process. Calcium sulphate + gentamicin was implanted in the right tibia to induce a physical stimulus without bacterial multiplication. After four weeks, the animals underwent 18F-FLT PET imaging, bacterial culturing and tissue pathology. The uptake of 18F-FLT was significantly higher in the abscess site compared with that in the granuloma, with maximum standardised uptake values of 5.76±0.25 and 1.15±0.32, respectively (P<0.01). This indicates that 18F-FLT is not a specific tumour tracer since active inflammation also results in the uptake of this compound. However, the tumour specificity of this tracer is higher compared with that of 18F-fluorodeoxyglucose. Therefore, 18F-FLT may be useful in the differential diagnosis of benign and malignant tumours.