Effects of i.v. contrast administration on intraspinal and paraspinal tissues: a CT study. 1. Measurement of CT attenuation numbers.

Contrast-enhanced CT can be useful in differentiating between recurrent disk herniation and scar formation after disk surgery. Thirty such CT studies were assessed retrospectively to determine the utility of CT attenuation measurements in identifying intraspinal pathology. Measured values of intraspinal tissues, but also of "reference" materials such as CSF, blood, and muscle tissue, showed large individual variations; and enhancement patterns for recurrent herniation and scar formation were not specific. The chief value of contrast administration may lie in the clearer definition that is gained of various structures within the postoperative spine.