Nonionic monomers and dimers.

The 10-year-long debate regarding high-os-molar ionic vs low-osmolar nonionic contrast media has ceased. Now we are confronted with at least eight nonionic monomers and two nonionic dimers. Do these ten contrast agents differ from each other? The manufacturers say yes, but in clinical practice differences have, with a few exceptions, turned out to be very marginal and by no means to the extent which was found between high- and low-osmolar contrast media. Only time will tell whether there are any major differences of clinical importance between the "old" and the new nonionic agents.