Hybrid subtraction in digital fluorography

Digital fluorography using temporal subtraction techniques has achieved excellent visualization of the vascular anatomy with intravenous injections of contrast medium. However, clinical studies have demonstrated that a major limitation to this method is patient motion. Movements such as swallowing, breathing, peristalsis, cardiac motion, and arterial pulsations cause artifacts in difference images which can reduce the diagnostic accuracy of the procedure. Many of these artifacts can be eliminated by the use of hybrid subtraction, a second-order technique which combines temporal and dual-energy subtraction. This procedure is described and compared to both temporal and dual energy subtraction methods in terms of data acquisition, iodine signal-to-noise ratios, dose, and x-ray tube loading. Images are shown to demonstrate the viability of this new technique.