Previous applications of digital subtraction angiography (DSA) to the assessment of ventricular function, particularly during exercise, have been limited by cardiac, respiratory, and gross patient motion. Dual-energy DSA, however, is insensitive to motion, and makes DSA imaging readily applicable to cardiac patients. For the first time, dual-energy subtraction is available in a clinical cardiac catheterization laboratory. The purpose of this research is to apply the dual-energy technique to patients with cardiac disease, and quantitatively assess both global and regional left ventricular function during rest and exercise. More specifically, the aims are: Firstly, exploiting the motion immunity of this technique, it is proposed to develop and apply a digital subtraction dual-energy ventriculographic exercise stress test using a right heart catheter. This exercise test will be utilized to assess the functional significance of coronary stenoses at the time of cardiac catheterization. Secondly, a videodensitometric analysis of dual-energy subtraction images is under investigation to test the hypothesis that absolute global left ventricular volumes can be accurately measured independent of geometric assumptions, This will be done using a direct measure of blood iodine concentration. Thirdly, it will be determined whether accurate volume measurements can be made without direct sampling of the blood iodine concentration. Thus, absolute volume determinations may be possible without the need of arterial catheterization. Fourthly, a phase-matched rest/exercise wall motion display is being developed to quantitate regional myocardial function independent of cardiac coordinate systems. Phase- matching refers to the superposition of two images at the same point in the cardiac cycle, one at rest and one during exercise. The results of this research will provide improved methods of assessing the functional significance of coronary stenoses in patients. Furthermore, these techniques have the potential to provide a high resolution outpatient test for coronary artery disease and for the serial assessment of rest and exercise ventricular function in patients with cardiac disease.
