Comparison of 18F-sodium fluoride positron emission tomography and CT: An exploratory study in 12 dogs with elbow pain

18F-Sodium Fluoride (18F-NaF) positron emission tomography (PET) provides high resolution functional information about bone activity and can be fused with CT images to improve three-dimensional localization and characterization of lesions. This prospective, observational study assessed 18F-NaF PET-CT for imaging of canine elbows, compared PET with CT findings, and assessed correlation with lameness. Twelve patients with elbow pain were included. Cases included primarily young, large breed dogs. A three-level clinical lameness score was assigned to each forelimb. All dogs had bilateral elbow joints imaged with CT and PET under general anesthesia, approximately 1.5 h after intravenous injection of 3 MBq/kg of 18F-NaF. Imaging findings were independently reviewed by two radiologists using a three-level scoring scheme over nine anatomical regions in the elbow. PET imaging identified areas of bone activity where minimal change was identified on CT. PET imaging also demonstrated absence of uptake in areas where modeling was present on CT. A stronger correlation was observed between clinical grades and PET scores (r2  = 0.38, P = .001) than between clinical grades and CT scores (r2  = 0.17, P = .048). The total PET scores were significantly different for each clinical grade (P = .013) but total CT scores did not differ (P = .139). This exploratory study suggests that PET improves the ability to detect lesions and to determine the clinical significance of CT findings in dogs with elbow pain.

Arthroscopic features of primary and concomitant flexor enthesopathy in the canine elbow

Objectives: To investigate the possibilities and limitations of arthroscopy to detect flexor enthesopathy in dogs and to distinguish the primary from the concomitant form.

Materials and methods: Fifty dogs (n = 94 elbow joints) were prospectively studied: dogs with primary flexor enthesopathy (n = 29), concomitant flexor enthesopathy (n = 36), elbow dysplasia (n = 18), and normal elbow joints (n = 11). All dogs underwent an arthroscopic examination of one or both elbow joints. Presence or absence of arthroscopic characteristics of flexor enthesopathy and of other elbow disorders were recorded.

Results: With arthroscopy, several pathological changes of the enthesis were observed in 100% of the joints of both flexor enthesopathy groups, but also in 72% of the joints with elbow dysplasia and 25% of the normal joints. No clear differences were seen between both flexor enthesopathy groups.

Clinical significance: Arthroscopy allows a sensitive detection of flexor enthesopathy characteristics, although it is not very specific as these characteristics may also be found in joints without flexor enthesopathy. The similar aspect of both forms of flexor enthesopathy and the presence of mild irregularities at the medial coronoid process in joints with primary flexor enthesopathy impedes the arthroscopic differentiation between primary and concomitant forms, requiring additional diagnostic techniques to ensure a correct diagnosis.

Magnetic resonance imaging of primary and concomitant flexor enthesopathy in the canine elbow

Flexor enthesopathy is a recently recognized elbow disorder in dogs and considered to be an important differential diagnosis for elbow lameness. Primary and concomitant forms of the disease have been previously described and treatments differ for the two forms. The goal of this prospective study was to compare magnetic resonance imaging (MRI) findings for dogs with primary flexor enthesopathy (n = 17), concomitant flexor enthesopathy (n = 23), elbow dysplasia alone (n = 13), and normal elbows (n = 7). Each elbow joint underwent MRI using the same low-field scanner. Sequences included transverse and sagittal T1-weighted (before and after IV contrast), transverse and sagittal T2-weighted, and dorsal STIR. For each elbow, MRI lesions were recorded based on a consensus of two observers unaware of group status. Magnetic resonance imaging lesions involving flexor tendons were found in 100% of clinically affected joints with primary flexor enthesopathy and 96% of clinically affected joints with concomitant flexor enthesopathy. Thickened flexor muscles were the most common lesions, followed by hyperintense tendon signal and contrast enhancement. Irregular, thickened medial humeral epicondyle, edema, and calcified body lesions were less frequently observed. Magnetic resonance imaging characteristics of flexor enthesopathy were not found in normal joints or those affected by elbow dysplasia alone. No significant differences in frequencies and details of individual MRI characteristics were found between primary and concomitant flexor enthesopathy groups. Findings indicated that MRI is a sensitive technique for detection of flexor enthesopathy lesions in dogs, however, MRI characteristics do not allow differentiation of primary versus concomitant forms of the disease.