PET kinetic modeling of rat tumors simultaneously treated with photodynamic therapy: A reference tissue model

The aim of this work was to assess by kinetic modeling the effects of the photodynamic therapy (PDT) of cancer in two mammary adenocarcinoma tumors implanted in the axillary areas of rats. One tumor served as control while the other was treated with red light 24 hours after administration of two types of photosensitizers: AlPcS4 and ZnPcS2. PET scans were carried on, with a continuous infusion of fluorodeoxyglucose (FDG), during 2 hours including the 30 min duration of the illumination of the tumor. Images reconstructed in 120 frames of 60 sec each. A reference-region kinetic model or 6k-model was introduced to include the effects of the treatment. Since the blood supply to the tumors was affected by the illumination during the PET scans, the input curve was derived from factor analysis. A study of the FDG kinetic compartment model and rate constants is presented for both AlPcS4 and ZnPcS2