The use of fluorine‐18‐fluorodeoxyglucose‐positron emission tomography/computed tomography as an effective method for staging in dogs with primary appendicular osteosarcoma

Fluorine‐18‐fluorodeoxyglucose (18F‐FDG) positron emission tomography/computed tomography (PET/CT) has been utilized in veterinary medicine to improve the detection and characterization of primary, recurrent, and secondary neoplasms; but its use as a staging tool for dogs diagnosed with appendicular osteosarcoma has not been published. The purpose of this retrospective, case series, descriptive study was to detail the use of18F‐FDG PET/CT for staging a population of dogs with appendicular osteosarcoma, report the detection rate of secondary neoplastic lesions, and compare findings with published detection rates for other historically used imaging modalities. Seventy‐one client‐owned dogs with a confirmed diagnosis of appendicular osteosarcoma and staged with a whole‐body18F‐FDG PET/CT scan near the time of initial diagnosis were included. Each PET/CT study was re‐evaluated for malignancy distinct from the primary disease entity based on a collective qualitative and quantitative assessment of18F‐FDG uptake, CT appearance, and contrast enhancement characteristics. Following re‐evaluation of each study, information pertaining to tissue sampling performed on identified lesions was retrieved from the medical record when available. Staging with18F‐FDG PET/CT identified 17 of 71 (23.9%) and 12 of 71 (16.3%) dogs with a high suspicion or confirmation of a metastatic or comorbid malignant neoplasm respectively, with eight of 71 (11.3%) having both metastatic and comorbid lesions. The results of this study are suggestive that18F‐FDG PET/CT is effective in identifying both osseous and soft tissue secondary neoplastic lesions in dogs afflicted with appendicular osteosarcoma, yielding an increased detection rate of all lesions compared those previously reported for skeletal scintigraphy or whole‐body CT.