Physical and Radiological Aspects of CO2 Angiography

An important limitation of angiography in the diagnostic theatre is the intolerance or the toxicity of the iodinated contrast medium injected in the vessel to be visualized. This limitation is particularly strong in the most critical cases (diabetic vasculopathy, renal insufficiency). About thirty years ago the use of a biocompatible contrast medium was proposed, and the choice was Carbon dioxide. Carbon dioxide angiography is now a possible alternative of iodinated medium angiography and it is widely used all over in the world. But some important aspect of the procedure, due to the gaseous form, are not yet clearly described, and radiologists apply the technique more on the basis of a practical previous experience than on a deep knowledge of the physical and radiological concepts involved. The result is a limitation of the procedure diffusion and a diagnostic quality lower then expected. To clarify some mechanical aspects of the new procedure, we have studied three points: a) the pressure-flow relationship during the gas injection, b) the shape and structure of the gaseous jet, c) the quality of the obtained radiological image. The results have been obtained by using mechanical cardiovascular simulators mimicking the diagnostic conditions and may be useful to manage the diagnostic procedures to obtain the best results in all the operative conditions.