A comparison of CT scanning and myelography in the diagnosis of lumbar disc herniation.

Computerized tomographic (CT) scanning of the fourth and fifth lumbar disc spaces with the GE CT/T8800 scanner followed by metrizamide myelography was obtained for 134 consecutive patients with suspected lumbar disc disease. There was an overall concordance rate of 85% between CT scanning and myelography. In those 52 patients treated by surgery, concordance between the CT and the myelogram was similar at 86.5%. Myelography and surgical findings were in agreement in 94.2% of cases, while CT findings and surgical finding agreed in 92.3% of cases. The authors' data indicate that the CT scan is as accurate as myelography in the diagnosis of lumbar disc disease. When the CT scan interpretation is supported by clinical findings, the myelogram may be eliminated in the preoperative patient. Myelography may be reserved for equivocal cases.