Verification of scintigraphic imaging for injury diagnosis in 264 horses with foot pain.
BACKGROUND
Nuclear scintigraphy is commonly used as a diagnostic aid for foot pain, but there is limited information about different patterns of radiopharmaceutical uptake (RU) and their correlation with the results of other imaging modalities.


OBJECTIVE
To describe patterns of RU in horses with foot pain.


METHODS
Scintigraphic images of the feet of 264 horses with front foot pain were analysed subjectively and using region of interest analysis. Magnetic resonance images of all feet were analysed prospectively; the navicular bones were reassessed retrospectively and assigned a grade. A Spearman rank correlation test was used to test for a relationship between the scintigraphic grade of the navicular bone and magnetic resonance imaging (MRI) grade. Sensitivity and specificity of scintigraphy for detection of lesions in the deep digital flexor tendon (DDFT), the collateral ligaments (CL) of the distal interphalangeal (DIP) joint and the navicular bone were determined.


RESULTS
Increased radiopharmaceutical uptake (IRU) was detected in: a) the navicular bone (36.6%); b) pool phase images in the DDFT (13.0%); and c) at the insertion of the DDFT on the distal phalanx (14.3%). There was focal IRU at the insertion of the medial or lateral CL of the DIP joint in 9.4% and 1.5% of limbs, respectively. There was IRU in the medial and lateral palmar processes in 7.6% and 3.4% of limbs, respectively. There was a significant positive correlation between the scintigraphy grade and total MRI grade for the navicular bone and no difference between either focal or diffuse IRU and total MRI grade. There was high specificity, but low sensitivity of scintigraphy for detection of MR lesions of the navicular bone, the DDFT and the CLs of the DIP joint.


CONCLUSIONS
Positive nuclear scintigraphic results are good predictors of injury or disease of the navicular bone, DDFT and CLs of the DIP joint. However, a negative scintigraphic result does not preclude significant injuries.


CONCLUSIONS
Nuclear scintigraphy is a useful tool in the investigation of foot lameness and may help to determine the significance of MR lesions, especially if >1 lesion is identified that may be contributing to lameness.
Dyson
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S
Centre for Equine Studies, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU, UK.
Murray
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R
D000818:Animals; D005260:Female; D005534:Foot Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary*; D006724:Hoof and Claw; D006734:Horse Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D006736:Horses; D007270:Injections, Intra-Articular / Q000662:veterinary; D007794:Lameness, Animal / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D008297:Male; D010146:Pain / Q000000981:diagnostic imaging / Q000662:veterinary; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013639:Tarsal Bones / Q000000981:diagnostic imaging* / Q000473:pathology