abs: Assessment of Dual Tracer Positron Emission Tomography in a Clinical Population of Horses with Lameness Localized to the Distal Tarsal/Proximal Metatarsal Region Large Animal Residents' Forum
Equine Surgery Resident University of California, Davis Davis, California
Assessment of Dual-Tracer Positron Emission Tomography in a Clinical Population of Horses with Lameness Localized to the Distal Tarsal/Proximal Metatarsal Region. Arndt S, Spriet M, Pige CE, Galuppo LD. University of California, Davis, School of Veterinary Medicine, Davis, CA.
Identification and differentiation of pain originating from the distal tarsal joints or the origin of the suspensory ligament can be challenging due to the complexity of regional anatomy. Dual-tracer (18F-Sodium Fluoride (NaF) and 18F-Fluorodeoxyglucose (FDG)) positron emission tomography/computed tomography (PET/CT) has not been reported for proximal suspensory imaging. To validate a protocol for 18F-NaF/18F-FDG PET/CT imaging of the distal tarsal/proximal metatarsal region in horses and to report the findings in horses with pain localized to this region. Twelve client-owned horses, presenting with hind limb lameness, underwent dual-tracer PET/CT imaging under a single anesthetic episode. Total imaging time did not exceed two hours and all horses recovered uneventfully. Osteoarthritis of the distal tarsal joints was found in 17/24 limbs. Remodeling of the metatarsal bone at the origin of the suspensory ligament was present in 12/24 limbs on CT images, with seven of these limbs showing increased uptake on PET. Twelve limbs had increased FDG uptake in the suspensory ligament, including three limbs where soft tissues had been considered normal on CT. Dual PET/CT imaging can be performed for tarsal/metatarsal imaging in horses under general anesthesia. The NaF PET data helped to distinguish active from inactive osseous lesions. The FDG data provided additional information to CT for assessment of the soft tissue. The main limitation of the study is the small sample size and the lack of a gold standard. This study highlights the value of PET/CT in identification of active suspensory desmopathy in horses with hind limb lameness.