Depth determination on stereoscopic digital subtraction angiograms.

The determination of depth on stereoscopic digital subtraction angiographic (DSA) images was evaluated. A "plus" phantom that contained simulated blood vessels of various sizes with various concentrations of contrast medium was used for the study. The vessels ranged in diameter from 0.46 to 1.35 mm, with concentrations of contrast material of 1.6%-25%. The images were evaluated by seven radiologists and six radiologic technologists. The detectability of depth separation increased as the iodine concentration and the vessel size increased. With stereoscopic DSA, correct identification of depth is possible more than 80% of the time for vessels approximately 1 mm in diameter and containing 3.1% contrast medium when the vessels are separated by more than 2.8 mm.