 
         
         Summary
         
         
            Objectives: Although magnetic resonance imaging (MRI) is reported to be superior to myelography
            to determine the location and site of first time disc herniation, comparison of these
            diagnostic methods in cases of recurrent intervertebral disc disease (IVD) herniation
            after a first surgery has not been evaluated. The objective was to compare the diagnostic
            accuracy of MRI and myelography in a series of dogs undergoing repeat surgical decompression
            for recurrent IVD extrusion when compared to the gold standard of surgery.
         
         
            Methods: Ten dogs with recurrent IVD herniation underwent MRI and myelography followed by
            surgical decompression. Three observers reviewed the images to determine the site
            and side of the first surgery and the recurrent lesion. Agreement was determined by
            calculating a kappa (κ) score.
         
         
            Results: Substantial interobserver agreement was noted for recurrent lesion site using MRI
            and myelography (κ = 0.77 vs. 0.73) and when comparing MRI and myelography to the
            reported surgical site (κ = 0.73 vs. 0.67). Interobserver agreement was greater with
            MRI for circumferential location compared to myelography (κ = 0.76 vs. 0.43), similar
            to what was found when comparing to surgical side (κ = 0.82 vs. 0.49). The previous
            surgical site in this study had no effect on ability to identify the new lesion.
         
         
            Clinical significance: Despite the limitations of MRI, there was greater agreement between observers using
            MRI for both the recurrent and first lesion.
         
         Keywords
Magnetic Resonance Imaging - MRI - thoracolumbar intervertebral disc disease - dogs
            - myelography - recurrent