The normal appearance of CT myelograms.

PURPOSE: CT myelography has been used since 1976 to diagnose neural compression in the axial skeleton. With the advent of routine MRI, its role in accurately diagnosing neural compression has been questioned as its normal appearances are not defined in the study. In this study, we examine a series of CT myelograms to define the normal appearances of the neural elements of the spine. METHODS: The CT myelograms of patients with unilateral symptoms were examined by four independent physicians. The lateral extent of contrast was examined and recorded. Concordance between the recorded extents was assessed using kappa scores. RESULTS: Thirty-six scans were reviewed. Kappa analysis shows that there is a fair agreement in the lateral extent of contrast at L1, L3 and L4. At L2 and L5, agreement is slight. CONCLUSION: The interpretation of CT myelography shows significant interobserver variability. As a result, the usefulness of this diagnostic tool can be questioned, and if misinterpreted, it could lead to questionable diagnoses and inadvertently erroneous management if used in isolation. These slides can be retrieved under Electronic Supplementary Material.