Comparative Safety of Intracarotid Iopamidol, Iothalamate Meglumine, and Diatrizoate Meglumine for Cerebral Angiography

The neurotoxicity of a new nonionic iodinated contrast medium, iopamidol, was compared with standard ionic contrast media presently used for cerebral angiography. Studies were done with rabbits using trypan blue to monitor blood-brain barrier (BBB) integrity and I-125 HIPDm autoradiography to estimate regional cerebral blood flow (rCBF) or cellular metabolism following the intracarotid infusion of saline, iothalamate meglumine (Conray) or iopamidol. Intracarotid Conray resulted in barrier disruption (3/4) and decreased HIPDm (4/4) distribution whereas intracarotid iopamidol and saline resulted in neither barrier breakdown nor rCBF abnormality. The intravertebral infusion of diatrizoate meglumine in nonhuman primate studies resulted in BBB breakdown as defined in vivo using technetium-99m (99mTc) glucoheptonate and single photon emission computed tomography (SPECT) scanning, whereas intravertebral iopamidol did not cause barrier disruption. In a randomized, double-blind trial in humans, iopamidol infusion (n = 57) into the common carotid artery resulted in significantly less heat and pain than iothalamate meglumine (n = 53). There was no evidence of neurologic adverse reaction, abnormal enhancement on computer tomography (CT) scan done immediately after angiography, or electroencephalogram (EEG) alteration in either group. The intracarotid or intravertebral injection of nonionic iopamidol causes less patient discomfort and less experimental neurotoxicity than presently used ionic contrast materials.