The effect of contrast medium viscosity on the blood-brain barrier after intracarotid injection in the rabbit.

This study was undertaken to investigate the role of contrast medium viscosity in blood-brain barrier disruption after carotid angiography. Test solutions were injected into the carotid arteries of rabbits, and the degree of disruption was assessed by using 99mTc-pertechnetate and Evans blue as quantitative and qualitative markers, respectively. The seven test solutions consisted of basic solutions of physiological saline, iopromide, or methylglucamine iothalamate plus solutions derived from these by the addition of sufficient gelatin to augment their viscosities considerably. The solutions were injected over a 30-sec period, resulting in doses that varied inversely with viscosity. One of the high-viscosity solutions was also injected as a fixed dose, equal to the mean injection volume of its low-viscosity counterpart, without regard to the time used. Statistical comparison between the effects of the solutions showed that, under the conditions of the study, contrast medium viscosity, either by itself or as a consequence of its association with hyperosmolality, has no significant effect on the blood-brain barrier. However, under conditions of constant injection volume, higher viscosity solutions may require increased injection times, and this may lead to increased disruption of the blood-brain barrier.