Ventriculography With Colloidal Thorium Dioxide

As a means of delineating the ventricular system, we have found that colloidal thorium dioxide has a number of advantages that are not possessed by air. Whether these advantages will outweigh the possible disadvantages and dangers is not yet clear, although from an experience of nearly two years in the use of the material the advantages seem to preponderate. Colloidal thorium dioxide is freely miscible with the ventricular fluid, permitting ready diffusion throughout the cavities. It is also of high specific gravity, tending to reach the dependent points in the ventricular system, outlining the aqueduct and the fourth ventricle. It is of high radiopacity, so that only small quantities are necessary for the satisfactory visualization of the whole system. In cases in which the fluid pathways are free from obstruction it passes readily to the subarachnoid space and is eliminated within four hours from the cranial cavity, at least in