A qualitative comparison of two contrast media for cerebral angiography. A clinical method.

A qualitative comparison of two contrast media for cerebral angiography with regard to contrast should, preferably, be based on a comparison made in two different hemispheres of one patient. Two problems then arise which made evaluation difficult. Vasodilation occurs after the first contrast injection as a result of which the second contrast medium to be compared flows into a dilated vascular tree. In addition, in the case of a comparison in two different hemispheres, variations of image geometry occur, resulting in differences of sharpness and contrast. The method of solving these problems is discussed and is illustrated by a comparison of two contrast media which might be expected to produce differences in contrast because of their physical properties. The results of this clinical comparison show that the expected differences can be partly demonstrated.