Contrast Media and Special Radiographic Techniques

1
Contrast Media and Special Radiographic Techniques

• Chapter 10

2
Types of Contrast

• Ethiodized Oils
• Used to be common in bronchography and
  myelography
• Primary use today is in lymphography it is
  injected into the lymphatic vessels to visualize
  the vessels themselves and the nodes

3
Cont.

• Water-soluble Iodine Compounds
• Most frequently used other than barium
• Different types, brands, strengths
• Intravenously, intra-arterial, direct injection
  to structure
• Bolus substantial IV dose at once
• The higher the concentration, the more viscous,
  the more contrast and usually the more toxic
• Osmolality number of particles in solution per
  kg of water. Compounds that contain more iodine
  atoms per molecule can provide the desired
  contrast with fewer molecules, thus a lower
  osmolality. Osmolality plays a big role in the
  adverse effects of contrast and risk is reduced
  when the osmolality is lowered.
• Ionic contrast media whose molecules dissociate
  into two charged particles
• Non-ionic media whose molecules remain whole in
  solution
• Viscosity measure of resistance of fluid to
  flow high viscosity- thick and syrupy, low
  viscosity- thin and watery

4
More Contrast Facts

• The toxicity of a contrast medium on the body is
  related to the chemical configuration, the iodine
  concentration, the osmolality, ionization
  characteristics, the rate of injection and the
  dosage.
• Contrast that are nonionic, low osmolar with low
  iodine concentration and slowly injected are less
  likely to cause adverse reactions.

5
HOCA and LOCA

• HOCA high osmolar contrast agent (Renografin,
  Hypaque)
• LOCA low osmolar contrast agent
• Intrathecal within the spinal canal
• Many new LOCAs are also nonionic Isovue,
  omnipaque

6
Contrast Precautions

• Patients may have allergic reactions to contrast,
  be it mild or severe.
• Laboratory Values BUN (blood urea nitrogen)
  7-18 mg/dl creatinine 0.6-1.5 mg/dl
• Diabetic patients discussion

7
Patient History in relation to Allergic Reactions

• The history is the most reliable predictor of a
  patient reaction to contrast media
• Some signs of an adverse reaction are nausea,
  urticaria (hives), asthmatic shock, anaphylactic
  shock
• Nausea is a common side effect not considered to
  be an allergic response