Mann KA, Kraft SL, Hauke SM, et al.
Introduction/Purpose: 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) has been shown to predict tumor outcome of human osteosarcomas (OSA) and may provide valuable staging and prognostic information as well as therapeutic response assessment in veterinary patients. Our objective was to determine the baseline PET/CT characteristics of naturally occurring canine osteosarcoma and apply quantitative PET image analysis methods, as part of ongoing longitudinal studies to evaluate patient response to novel therapies and conventional treatments.
Methods: A Philips Gemini TF Big Bore PET/CT instrument was used to perform whole body 18F-FDG studies on 42 canine osteosarcoma patients admitted to the CSU Veterinary Teaching Hospital between December 2009 and June 2014. All patients were placed under general anesthesia and positioned for the exam prior to intravenous 18F-FDG injection (0.12-0.18 mCi/kg; 4.4-6.6 MBq/kg). During the 60 minute uptake time, pre- and post-contrast CT images were obtained prior to PET acquisition. Tumor maximum standardized uptake values (mSUV) and pattern of 18F-FDG uptake (FOG metabolism) were evaluated using commercial software (Extended Brilliance Workstation, Phillips Medical Systems).
Results: Thirty-seven patients were large or giant breeds and five were mixed breed (weight range=17-80 kg; mean=43.5 kg; median=39.7 kg). Patient genders were 20 spayed females, 20 castrated males and 2 intact males. Median age was 9.6 years (range=1.2- -13.6 years). Pattern of 18F-FDG uptake in each tumor was nonuniform, with greatest intensity of radiopharmaceutical occurring in the regions of greatest osteolytic activity (intramedullary or extramedullary). Maximum SUV ranged from 1.8 to 24.9 (mean=9.1 ; median=7.8; SD=5.5).
Discussion/Conclusion: Region-of-interest analysis of mSUV was performed as it has been shown to have prognostic significance for human OSA. In future studies, our baseline PET/CT characteristics and mSUV analysis will be compared to post-therapy PET/CT exams in canine OSA patients to evaluate prognostic value. Variability in the 18F-FDG intensity pattern and mSUV reflect the heterogeneous nature of this tumor type. Osteolytic tumor regions were the most hypermetabolic and osteoblastic regions tended to have less intense radiopharmaceutical uptake.