CT recognition of thorotrast-induced intracranial and lumbar arachnoiditis.

In the 1930s and 1940s the radioactive contrast material colloidal thorium dioxide (Thorotrast) was frequently used in radiographic examinations. The agent was used mainly for angiography and to a lesser extent for myelography, ventriculography, pyelography, and hepatolienography. The late clinical complications and conventional radiographic manifestations of thorium administration have been well documented. We report a case of chronic arachnoiditis and myelopathy to illustrate the unusual but probably diagnostic computed tomographic (CT) appearance of the head and spine.