(RadioGraphics. 1985;5:83-104.)
© RSNA, 1985

Computers in Digital Imaging

¹ Department of Radiology, Cleveland Clinic, Cleveland, Ohio

Digital subtraction angiography established the concept and presence of the computer in diagnostic radiology. The computational requirements for DSA have, for the most part, been fairly humble. Logarithmic subtraction, frame integration and image enhancement techniques are used in a relatively minor role. The basic requirement for computers in DSA is spatial resolution (matrix size) and consequently disk speed. The problem, therefore, is to match the resolution of the system appropriately to the clinical need. One of the growing uses of DSA is the intraarterial examination. The advantages of window and center line adjustment coupled with immediate visualization of the images makes for a very attractive procedure from the standpoint of consistent, high quality examinations. As shown in Figures 23A and B, intraarterial examinations eliminate motion artefacts and the effects of inadequate iodine concentrations that may be seen in intravenous studies. For these images to be able to demonstrate vessels that are less than a millimeter in diameter, however, improvement in spatial resolution by increasing the acquisition matrix to 1024 x 1024 will be needed. The major challenge in DSA at present, therefore, lies in solving the problems of the acquisition rate and bulk storage of these images. The development of optical disc technology has progressed to a point at which the solution is evident, but it still awaits development.

[See figure in the PDF file]