Recognition of anatomical predilection sites in canine elbow pathology on bone scans using micro-single photon emission tomography

Primary and concomitant flexor enthesopathy of the canine elbow

Objectives: To report the characteristics of two types of flexor enthesopathy, primary and concomitant, based on different diagnostic techniques.

Materials and methods: Over a period of three years a prospective study was performed on dogs admitted for the complaint of elbow lameness. Based on the radiographic findings a selection of dogs underwent a complete series of different imaging modalities. With each technique, pathology of the medial epicondyle and the presence of other elbow disorders were recorded. All joints with signs of flexor pathology apparent with at least three techniques were selected. A distinction was made between primary and concomitant flexor enthesopathy based on the absence or presence of other elbow disorders.

Results: Primary flexor enthesopathy was diagnosed in 23 joints and concomitant flexor enthesopathy in 20 joints. In 43% of the joints with primary and in 75% of the joints with concomitant flexor enthesopathy, pathology at the medial epicondyle was demonstrated by all techniques. All joints with concomitant flexor enthesopathy had a diagnosis of medial coronoid disease, osteochondritis dissecans, or both.

Clinical significance: Pathology at the medial epicondyle is a sign of flexor enthesopathy. It may be present as the only sign in a joint with primary flexor enthesopathy or concomitant with other elbow pathology. In both groups flexor lesions can be demonstrated with different imaging techniques. The distinction between the primary and concomitant form is based on the presence or absence of other elbow pathology, mainly medial coronoid disease. Recognizing both types is important for a correct treatment decision.

The use of planar bone scintigraphy and HiSPECT for diagnosis of primary and concomitant flexor enthesopathy in the canine elbow

Objective: To investigate the possibilities and limitations of planar bone scintigraphy and high resolution single photon emission computed tomography (HiSPECT) to diagnose flexor enthesopathy and to distinguish primary flexor enthesopathy from the concomitant form.

Materials and methods: A prospective study of 46 dogs with primary flexor enthesopathy, concomitant flexor enthesopathy, medial coronoid disease, and normal elbows was performed. All dogs underwent planar bone scintigraphy and HiSPECT imaging. The obtained images were visually scored for increased radiopharmaceutical uptake in the medial humeral epicondylar and medial coronoid process region using a score from 1-3.

Results: Planar bone scintigraphy demonstrated increased radiopharmaceutical uptake in all diseased elbow joints, except for one. HiSPECT demonstrated increased radiopharmaceutical uptake of the medial humeral epicondyle in nearly all clinically affected joints with primary and concomitant flexor enthesopathy. Additional uptake of the medial coronoid process was recorded in all clinically affected joints with concomitant flexor enthesopathy and in six out of 18 with primary flexor enthesopathy. No difference in intensity of the uptake was noticed.

Clinical significance: Planar bone scintigraphy allows the attribution of lameness to the elbow joint in cases of primary flexor enthesopathy with minimal or even absent radiographic changes. The more detailed HiSPECT enables the localization of pathology within the elbow joint and is a sensitive technique to detect flexor enthesopathy. However HiSPECT is insufficient to distinguish primary from concomitant flexor enthesopathy.

Assessment of medial coronoid disease in 180 canine lame elbow joints: a sensitivity and specificity comparison of radiographic, computed tomographic and arthroscopic findings

Background

Diagnostic imaging is essential to assess the lame patient; lesions of the elbow joint have traditionally been evaluated radiographically, however computed tomography (CT) has been suggested as a useful technique to diagnose various elbow pathologies. The primary objective of this study was to determine the sensitivity and specificity of CT to assess medial coronoid disease (MCD), using arthroscopy as gold standard. The secondary objective was to ascertain the radiographic sensitivity and specificity for MCD compared with CT.

Methods

For this study 180 elbow joints were assessed, of which 141 had been examined with radiography, CT and arthroscopy; and 39 joints, had radiographic and CT assessment. Sensitivity and specificity were calculated for CT and radiographic findings using available statistical software.

Results

Sensitivity and specificity of CT using arthroscopy as gold standard resulted in high values for sensitivity (100 %) and specificity (93 %) for the assessment of MCD. For the radiographic evaluation, a sensitivity of 98 % and specificity of 64 - 69 % using CT as the technique of reference, were found.

Discussion

These results suggest that in case of doubt during radiographic assessment, CT could be used as a non-invasive technique to assess the presence of MCD.

Conclusion

Based on the high sensitivity and specificity obtained in this study it has been considered that CT, rather than arthroscopy, is the preferred noninvasive technique to assess MCD lesions of the canine elbow joint.

PET and SPECT imaging in veterinary medicine

Veterinarians have gained increasing access to positron emission tomography (PET and PET/CT) imaging facilities, allowing them to use this powerful molecular imaging technique for clinical and research applications. SPECT is currently being used more in Europe than in the United States and has been shown to be useful in veterinary oncology and in the evaluation of orthopedic diseases. SPECT brain perfusion and receptor imaging is used to investigate behavioral disorders in animals that have interesting similarities to human psychiatric disorders. This article provides an overview of the potential applications of PET and SPECT. The use of commercially available and investigational PET radiopharmaceuticals in the management of veterinary disease has been discussed. To date, most of the work in this field has utilized the commercially available PET tracer, (18)F-fluorodeoxyglucose for oncologic imaging. Normal biodistribution studies in several companion animal species (cats, dogs, and birds) have been published to assist in lesion detection and interpretation for veterinary radiologists and clinicians. Studies evaluating other (18)F-labeled tracers for research applications are underway at several institutions and companion animal models of human diseases are being increasingly recognized for their value in biomarker and therapy development. Although PET and SPECT technologies are in their infancy for clinical veterinary medicine, increasing access to and interest in these applications and other molecular imaging techniques has led to a greater knowledge and collective body of expertise for veterinarians worldwide. Initiation and fostering of physician-veterinarian collaborations are key components to the forward movement of this field.

The use of the HiSPECT bone scan in canine flexor enthesopathy and coronoid pathology

In this study the use of the high resolution Micro-Single Photon Emission Tomography (HiSPECT) system with a radioactive bonemarker, (99m)Tc-oxidronate, was evaluated in dogs with coronoid pathology and/or flexor enthesopathy. Sixty-five elbows of 34 dogs were included. CT and HiSPECT were performed on all elbows, arthroscopy on 59. Tracer uptake in 8 anatomical regions was graded according to two models. Increased activity in the medial epicondylar region was associated with flexor pathology on CT (P=0.0002) and arthroscopy (P<0.0001) and increased uptake in the medial coronoid (P<0.0001) and the medial condylar area (P<0.013) with coronoid pathology. Uptake in the remaining areas was not associated with both pathologies. In conclusion, the improved resolution of the HiSPECT system allows identification of increased tracer uptake in the anatomical regions involved in coronoid pathology and flexor enthesopathy. This modality may improve the diagnostic potential of the bone scan in canine elbow disease.

Evaluation of semi-quantitative bone scintigraphy in canine elbows

Scintigraphy is an extremely sensitive tool for the detection of early changes in bone metabolism. Sixty-eight lame dogs underwent a scintigraphic examination. For each elbow lateromedial (LM), caudomedial (CdM) flexed and caudomedial (CdM) extended scintigraphic views were obtained. Semi-quantitative analysis was performed to determine radiopharmaceutical uptake at the medial coronoid process (MCP) and at the attachment of the flexor muscles at the medial humeral epicondyle, normalised to activity registered in either the total elbow joint or the radius/ulna. MCP pathology/flexor enthesopathies were divided into simple (containing one abnormality) or complex (containing more than one abnormality) lesions. The influence of different views or normalisation procedures on sensitivity and specificity was evaluated. MCP lesions were detected on radiography, ultrasound, computed tomography, magnetic resonance imaging and/or arthroscopy in 49 elbows, with 13 simple and 36 complex lesions. Flexor enthesopathy was diagnosed in 54 elbows, with 14 simple and 40 complex lesions. In seven elbows only degenerative changes were present, whereas in 50 elbows no abnormalities could be detected. MCP lesions were best detected with the CdM extended view, whereas for flexor enthesopathy the CdM flexed view offered the best result. To detect simple lesions, the normalisation procedure to the elbow gave the best result, whereas normalisation to the radius/ulna was the best choice for complex lesions. This study suggests that semi-quantification is a valuable method in case of simple pathology, especially when MCP lesions are considered. For elbows with complex lesions, the quantification procedure is less reliable.

Regional brain perfusion in 12 cats measured with technetium-99m-ethyl cysteinate dimer pinhole single photon emission computed tomography (SPECT)

With the use of perfusion tracers, in vivo examination of the regional cerebral blood flow in cats can be performed with single photon emission computed tomography (SPECT). Reliable perfusion data of normal, healthy cats are necessary for future clinical studies or other research use. Therefore, this dataset of the regional perfusion pattern of the normal feline brain was created. Twelve cats were used in this study. Technetium-99m-ethyl cysteinate dimer ((99m)Tc-ECD) was injected intravenously and the acquisition, using a triple head gamma camera equipped with three multi-pinhole collimators (pinhole SPECT), was started 40 mins after tracer administration under general anaesthesia. Nineteen regions of interest were defined using 7T magnetic resonance images of the feline brain and a topographical atlas. Regional counts were normalised to the counts of two reference regions: the total brain and the cerebellum. The highest tracer uptake was noticed in the subcortical structures, and the lowest in the frontal cortex and the cerebellum. Also left-right asymmetry in the temporal cortex and a rostrocaudal gradient of 5% were observed.