Application of Homomorphic Deconvolution to Dilution Curves

The application of a homomorphic deconvolution technique to indicator dilution curves is investigated. An indicator dilution curve with recirculation is decomposed into the primary circulation and the first recirculation components by homomorphic filtering. First, the method is applied to a simple model in which a dilution curve with recirculation is represented by mathematical functions. The assumed mean transit time and shunt fraction are determined from the two decomposed curves. Second, the method is applied to real data, i.e., the pulmonary time-activity curves from radionuclide angiocardiography. Pulmonary-to-systemic flow ratios are calculated from the areas of two decomposed curves and compaxed with those from cardiac catheterization. It may be concluded that homomorphic deconvolution seems to be a possible method of recovery of the primary circulation curve and also of the first recirculation curve from an indicator dilution curve with recirculation.