Prospective pilot study utilizing changes in quantitative values obtained on serial fluorine-18 fluorodeoxyglucose (F-FDG) positron emission tomography-computed tomography (PET/CT) in dogs with appendicular osteosarcoma before and after stereotactic body radiation therapy (SBRT) and carboplatin chemotherapy to assess for prediction of survival and therapeutic effectiveness.

Abstract

Serial fluorine 18 fluorodeoxyglucose (F-FDG) positron emission tomography-CT (PET/CT) is commonly used in human oncology to prognosticate and evaluate for therapeutic effectiveness. In this pilot study, dogs with naturally occurring appendicular osteosarcoma were evaluated with serialF-FDG PET/CT in an attempt to assess for response to therapy, prognostic factors, and appropriateness of imaging intervals. Fourteen dogs were enrolled in the trial. All dogs had the initialF-FDG PET/CT (PET1), with nine dogs having their end-of-therapyF-FDG PET/CT (EoT PET) 3 months after stereotactic body radiation therapy (SBRT) to the primary tumor. The median percent change from the PET1 to the EoT PET for the standard uptake value maximum (SUV) was -58% (range: -17 to -88%), metabolic tumor volume (MTV) was -99.8% (range: -65 to -100%), and total lesion glycolysis (TLG) was -99.8% (range: -75 to -100%), all of which were significant (P&#xa0;<&#xa0;.05, <.05, and <.05, respectively). On evaluation, it was found that volumes of GTV and CTV were significant for survival (P&#xa0;<&#xa0;.05 and <.05), MTV, TLG, and SUVon the EoT PET (SUV) were predictive of metastasis (P&#xa0;<&#xa0;.05), and the SUVwas significantly correlated to the time to first event (P&#xa0;<&#xa0;.05). Based on this data, serialF-FDG PET/CT performed 3 months after SBRT can show a significant reduction in avidity, and the quantitative data collected may help predict metastatic disease in canine appendicular osteosarcoma.