[en] Causes of the non-uniformity response to a flood source and their respective importance have been studied on an image intensifier camera. To improve this response, corrections on the spatial variations of energy response and the spatial distortions due to the coordinate computation principle for this camera have been performed. These corrections are made off line, by using a data processing system, on the list mode acquisition of spatial coordinates (X,Y) and energy information (W). They have improved the uniformity index from 35% to 7% on an acquisition that was made with a 20% spectrometric window. Clinical image quality has also been improved, as these corrections allows the use of a narrower spectrometric window (20% or less)

[en] 99mTc pertechnetate dilution method (TcM) is a reference for the left to right shunts (L→RS) evaluation as well as oxymetry is. Another radionuclide method using C¹⁵O₂ (CO₂M) was compared with TcM. The results obtained with CO₂M confirm the reliability of the CO₂M for the L→RS investigation. Characteristics of both non invasive radionuclide methods are summarized. The advantages of CO₂M are that it is always available even in presence of valvular insufficiency, severe congestive heart failure, multiple cardiac lesions and that it is always repeatable giving an intra assay control unaccessible to TcM and finally it produces a much lower radiation absorbed dose with a special interest for children investigations