Comparison of Computed Tomography and Myelography to a Reference Standard of Computed Tomographic Myelography in the Evaluation of Dogs with Intervertebral Disc Disease

Abstract

To compare the accuracy of myelography and CT to a reference standard of CT myelography in chondrodystrophic dogs with intervertebral disc extrusions. Study Design: Prospective blinded comparative study. Animals: Chondrodystrophic dogs with acute canine myelopathy due to intervertebral disc extrusions (n=33). Methods: Dogs received CT, myelography, and CT myelography to diagnose and localize intervertebral disc extrusions. The accuracy of CT and myelography was compared to CT myelography for lateralization, localization, and overall accuracy. Confidence in the assessment of each study was scored by readers. Results: The lateralizing, localizing, and overall accuracy of CT was 88%, 86%, and 84% respectively. The lateralizing, localizing, and overall accuracy of myelography was 59%, 69%, and 48% respectively. The accuracies of all three categories were significantly different between myelography and CT. Significant differences were found between confidence scores for both myelography and CT. Poor accuracy was obtained except for studies with the highest confidence score. Conclusions: CT is a more accurate imaging technique than myelography for diagnosing chondrodystrophic disc extrusions when using a reference standard of CT myelography. However, both techniques can yield high accuracy when the reader is confident in their assessment. Further imaging should be pursued when confidence in the localization is not high.