Left-to-right shunts. (Quantification, mathematical methods and their statistical comparison)

This work describes a non-traumatic technique for quantitative determination of left-to-right shunts. Various mathematical methods to evaluate the radioisotope concentration lung curve are considered. Data were collected with a gamma camera system connected to a computer. The first results were obtained from 18 patients at the Ospedali Riuniti in Parma, Italy. All the mathematical processes are described. The three methods used were based on: 1. the count ratio (C2/C1) between two pulmonary activity concentrations, 2. the gamma function fitting, 3. decreasing exponential. A comparison of the three methods shows that the gamma function method is the most reliable. In this kind of investigation the patient's radiation dose is low enough for it to be repeated so that the course of the disease can be followed.