Early Experience Using Dual 18F-NaF/18F-FDG PET/CT as a Diagnosis Tool for Pain of Unknown Origin in the Oral and Maxillofacial Region of Dogs

Pain of unknown origin in the oral and maxillofacial region is a common clinical problem in veterinary medicine. The differential diagnosis list is extensive and may include periodontal disease, endodontal disease, neoplasia, skeletal abnormalities and trauma, just to name a few.

Positron emission tomography (PET) is most used for oncologic imaging in dogs, however PET is not specific for neoplastic disease. Computed tomography is regarded as the modality of choice for oromaxillofacial imaging in small animals, but only provides structural imaging. The goal of this study was to assess whether the addition of dual tracer PET, using both 18F-Fluorodeoxyglucose (18F-FDG) and 18F-Sodium Fluoride (18F-NaF) to CT would be pertinent for oromaxillofacial imaging in dogs. Eight dogs presenting for assessment of oromaxillofacial pain were prospectively included in this study. Dual tracer PET and CT were performed under a single anesthetic episode using a PET-CT scanner with an extended axial field of view (480 mm). The main abnormalities identified included bilateral TMJ arthritis and coronoid process inflammation, a periapical lesion on the maxillary molar tooth, a deep lingual abscess, pterygoid myopathy and marked inflammation of the oropharynx. Injecting 18F-FDG first was identified as the preferred order, as the presence of marked 18F-NaF uptake in the alveolar bone tends to mask more subtle gingival 18F-FDG uptake. PET was pertinent at clearly identifying margins of inflamed areas and regional variation for assessment of periodontal disease. We conclude that dual tracer PET-CT is suitable as a pertinent imaging modality for advanced characterization of oromaxillofacial disease.