Recognition of lumbar disk disease: comparison of myelography and computed tomography.

A retrospective study was devised to determine the correlation between myelography and computed tomography (CT) in the recognition of abnormalities of the lumbar intervertebral disk. A group of 106 patients was studied who had had both myelography and CT within a 6 week period. Each examination was interpreted separately by a neuroradiologist who had no access to the patients' clinical findings or the results of any radiologic studies. On comparison of 290 interspace levels, there was agreement in definite abnormalities in 70%. Most discrepancies were due to suspicious findings and inconclusive studies of both kinds. In particular, there was poor correlation between the two examinations in the diagnosis of a slightly bulging disk. The major discrepancy rate was less than 5% overall and less than 1% among patients without prior surgery. On the basis of these findings, a diagnostic algorithm is suggested that would facilitate the workup of a similar group of patients.