Penetration of vascular contrast media into brain tissue and cerebrospinal fluid. An experimental study in rats

Recent studies suggest that intravenously administered contrast media (CM) penetrate into cerebrospinal fluid (CSF), and the concentration of CM in CSF increases significantly following acetazolamide or probenecid pretreatment. However, corresponding levels of CM in brain tissue and extracellular fluid (ECF) have not been reported. Adult anesthetized rats were injected intravenously with sodium/meglumine diatrizoate and iohexol. The control group received no pretreatment, and the pretreated group received acetazolamide and probenecid before the CM. The amount of each contrast agent was measured in brain tissue and in CSF by high performance liquid chromatography. Pretreated animals attained significantly higher CSF concentrations of diatrizoate and iohexol than control animals. However, tissue ECF concentrations in pretreated animals were not significantly different than in control animals for either agent. The results are consistent with the idea that a flushing action of CSF helps to remove CM from the brain ECF.