LearningRadiology - Thoratrast

Thorotrast

• Alpha-emitter

• Previously used for cerebral angiography and liver/spleen imaging

• Use started in early 30s and continued to early 50s

• Excellent opacifying agent “well-tolerated“ by patients

• Could produce intense fibrosis in muscle if it extravasated on injection and it was this side-affect which caused its use to be questioned first

• Colloidal thorium dioxide deposited in liver (70%), spleen (30%), bone marrow, lymph nodes

• Produces increased opacity of metal density in liver, spleen and celiac nodes

• May be visualized in soft tissues of neck if extravasated there

• Biologic half life of 400 years; physical half-life of 1010 years

• Hepatic dose in 20 years about 1000-3000 rads

• Produces angiosarcomas (hemangioendotheliomas) of liver (50%), cholangiocarcinoma, hepatoma

• One of the causes of “bone-within-a-bone” in spine

• Long latency period (25 years)

WH/93