Contrast materials are classified according to their density as radiolucent and radiopaque.
Radiolucent contrast agents
Air is gases such as oxygen and carbon dioxide.
They appear black on the X-ray.
Air can be used to create second contrast in double contrast barium column radiographs.
Easily absorbable carbon dioxide is used in angiography.
Radiopaque contrast agents
1) heavy metal salts (barium sulfate)
It is mainly used for the digestive system.
It is inert, not absorbed. When given alone, it is called single contrast, if given by air, it is called double contrast examination.
2) organic water-soluble iodine compounds
It can be used intravascularly, intrathecally and orally. An ideal iodinated contrast agent should have low osmolarity and high radiopacity.
3) lipiodol
It is a fat-soluble organic iodinated contrast agent. It is not used intravenously. It is used in conjunction with chemotherapeutics for lymphangiography and HCC chemoembolization in the liver.
Contrast agent side effects
Reactions to iodinated contrast media are between 5-12% and are common between the ages of 20-50.
Most are minor side effects such as nausea and vomiting.
Major side effects are divided into allergic and chemotoxic. Most of the reactions are allergic in nature.
Chemotoxic reactions depend on the high osmolarity and physical properties of the contrast medium. These reactions.
1) Hemolysis
2) Endothelial damage, disruption of the blood-brain barrier
3) Cardiac depression
4) Vasodilation
5) Hypervolemia
Risk factors in contrast agent use
Major risk factors
Age < 1 or > 50-60
History of contrast material allergy
Allergy/asthma
cardiovascular system disease
Minor reisk factors
Azotemia
DM
dehydration
blood dyscrasias
multiple myeloma
Anxiety
