Lumbar root compression in the lateral recess: MR imaging, conventional myelography, and CT myelography comparison with surgical confirmation

BACKGROUND AND PURPOSE: Previous authors have shown that conventional myelogra-phy is superior to plain CT in the assessment of root compression in the lateral recess, but this question has never been evaluated with respect to MR imaging of the lumbar level. Our purpose was to assess the accuracy of MR imaging, conventional myelography, and postmyelography CT (CT myelography) of the lumbar level in identifying degenerative lateral recess root compres-sion with surgical confirmation. METHODS: MR imaging, conventional myelography, and CT myelography of the lumbar level were assessed in the imaging of 58 lateral recesses at 38 lumbar levels in 26 patients who underwent surgery for radiculopathy with degenerative lateral recess abnormality. Each lateral recess was graded as normal, small without root compression, small with root compression, or severe root compression. RESULTS: MR imaging underestimated root compression in 28 % to 29 % of the cases in which root impingement was surgically confirmed. Conventional myelography underestimated root compression in only 5 % to 7 % of the cases and correctly predicted impingement in 93 % to 95%. CT myelography underestimated root compression in 38 % of the surgically confirmed cases