Parametric imaging using digital subtraction angiography

Abstract

Digital subtraction angiography following an injection of iodinated contrast material can regularly produce good quality images. In addition to the conventional anatomical information, the timed sequence of digital images also contains useful temporal information which hitherto has been largely ignored. A simple method of image processing is described which utilizes this timing information and present it as a color-coded set of functional images. Three parameters MAX, T-MAX and T-1/2 MAX are extracted from time-density curves, analogous to the time-activity curves of Nuclear Medicine, on a pixel-by-pixel basis. These parameters are used as a measure of overall organ perfusion, blood transit time between different vascular compartments, and as an indication of the initial delivery of contrast material to an organ. They have found use in the analysis of myocardial perfusion, before and after pharmacological intervention, and in the examination of the cerebral and renal circulations. The potential advantages of this techniques derive from its superior spatial, temporal and contrast resolution.