Vascular opacification by an organic iodide angiographic contrast medium is related to the ratio of agent to diluent (blood) at the instant of x-ray exposure. This implies a necessary conjunction of the properties of injectability and radiopacity of the contrast agent. The former is a function of viscosity, the latter of iodine content. Any attempt to increase iodine content of these contrast agents by augmenting concentration results in an elevation of viscosity. Therefore, the specific agent and the optimal concentration of the contrast solution desirable for maximum vascular opacification are not readily apparent.
Viscosity was determined for Hypaque 90% (2:1 mixture of methylglucamine and sodium diatrizoate), Urokon 70% (sodium acetrizoate), Neo-iopax 75% (sodium iodomethamate), Diodrast 70% (Iododyracet) and Miokon 90% (2:1 mixture of methylglucamine and sodium diprotrizoate), and for serial dilutions to 50% concentration for each of these contrast agents by means of a simple gravity-flow viscometer under standard
LANCE EM, KILLEN DA. The Organic Iodide Angiographic Contrast MediaRadiopacity and Viscosity of the Media as Related to Their Potential for Vascular Opacification. Arch Surg. 1961;83(2):210-211. doi:10.1001/archsurg.1961.01300140052009