Verification of scintigraphic imaging for injury diagnosis in 264 horses with foot pain.

The research paper evaluates the effectiveness of a diagnostic aid called nuclear scintigraphy for diagnosing foot pain in horses. The study found that while scintigraphy does have significant specificity in detecting issues in the navicular bone, deep digital flexor tendon (DDFT), and collateral ligaments (CL) of the distal interphalangeal (DIP) joint, it has a low sensitivity, meaning negative results from this method may not rule out injuries.

Objective and Methods

• This study aims to investigate the patterns of the uptake of radiopharmaceuticals, known as radiopharmaceutical uptake (RU), in horses suffering from front foot pain through the use of nuclear scintigraphic imaging.
• The scintigraphic images of the feet of 264 horses were scrutinized both subjectively and using region of interest analysis.
• Magnetic resonance images (MRI) of all the feet were examined, with the navicular bones subsequently reassessed and assigned a grade.
• A statistical method, Spearman rank correlation, was used to check if there was any significant correlation between the scintigraphic grades and the MRI grades of the navicular bone.

Results and Findings

• Increased radiopharmaceutical uptake (IRU) was observed in the navicular bone (36.6%), pool phase images in the DDFT (13.0%), and 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.
• IRU was also found in the medial and lateral palmar processes in 7.6% and 3.4% of limbs respectively.
• There was a significant positive correlation between scintigraphy grade and total MRI grade for the navicular bone.
• Despite high specificity of scintigraphic imaging, the sensitivity of this method for detecting MRI based lesions of the navicular bone, the DDFT and the CLs of the DIP joint was low.

Conclusions

• Though nuclear scintigraphy is a good predictor for identifying injuries or disease in the horse’s foot, a negative result does not necessarily rule out significant injuries.
• Therefore, scintigraphy is a helpful tool when investigating foot lameness in horses and can be particularly useful when determining the significance of MRI lesions, especially when more than one injury or lesion may be contributing to the lameness.