Effects of i.v. contrast administration on intraspinal and paraspinal tissues: a CT study. 2. Visual assessment.

Paired and matched CT scans, one before and one after IV injection of contrast material, from 30 spinal CT studies were presented in a blind fashion to six observers with varying degrees of radiologic experience. The observers were asked to indicate which section of each pair gave the best delineation of intraspinal soft tissues. Seventy-five percent of the verdicts indicated the postcontrast image was superior in this respect, but the six observers were unanimous on this in only 50% of the cases. At a follow-up viewing of the same cases several weeks later, some 20% of the verdicts were changed. Experience in interpreting spinal CT scans did not prove to influence rating performance or improve intraobserver consistency. In summary, contrast material, in the dosage and injection mode used by us, appeared to be the most important factor in improving scan interpretation.