Intra-arterial DSA: early experience with a 1024(2) matrix.

Twenty patients were studied with intra-arterial digital subtraction angiography (IA DSA), utilizing a 1024(2) matrix memory. Acquisition of the images was through a prototype television camera incorporating a finely focused electron beam. In five cases, comparison between a 512 X 512 (512(2)) matrix acquisition and a 1024 X 1024 (1024(2)) matrix acquisition mode was made, with injections occurring in the same vessel in the same patient. The clinical material demonstrated no significant improvement in image quality at the 4 1/2 as well as the 6 inch image intensifier (II) modes. However, the 1024(2) matrix combined with the 9 inch II mode showed foci of disease and normal anatomy with detail not always seen on the 9 inch II when a 512(2) matrix was used. In no case, however, was the basic diagnosis missed with the 512(2) matrix. Spatial resolution, as measured from lead bar test pattern images, demonstrated that the 1024(2) matrix allows a 70% or greater improvement in spatial resolution over the 512(2) for the 4 1/2, 6 and 9 inch II modes. For a given mode the radiation dose was held constant for the two matrix sizes.