NA;An angiographic contrast medium which would adhere to the endothelium of the cardiovascular system would increase the duration of the radiographic information while smaller doses injected at lower rates could be employed. Agar, gum acacia, polyvinylpyrrolidone (PVP), high and low molecular weight dextran, serum albumi, and gelatin were considered as additives to 60 meglumine diatrizoate. Agar and gum acacia did not yield solutions suitable for testing. The other solutions were tested for adhesiveness, and their electrical conductivity, as a possible toxicologic parameter, was measured in equiviscous solutions of 60‐65 cps. Low molecular weight dextran and serum albumin did not adhere. For solutions containing high molecular weight dextran, PVP, and gelatin, the washout times were significantly increased relative to 60 meglumine diatrizoate. Serum albumin lowered the conductivity of 60 meglumine diatrizoate by 30, low molecular weight dextran by 50, PVP by 3, high molecular weight dextran by 19, and gelatin by 32. Gelatin was considered the additive of choice since it conferred adhesiveness and it is non‐toxic and bio‐degradable. A type which was originally developed as a plasma expander was deionized, bleached, and depyrogenized. It was combined with diatrizoic acid in an attempt to form a stable compound. Results of infrared spectrography, Sephadex chromatography, and equilibrium dialysis proved that no compound or complex was formed. It was found that a solution of 6 or 8 gelatin in 60 meglumine diatrizoate provided a stable medium which upon injection into the vessel adhered to its walls for a period of several seconds.
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