Radiology Course Contrast Agents Ghione Emanuele Prof. Fabrizio Calliada

CONTRAST AGENTS History Definition Types RADIO - Contrast Agents 08/03/13 CONTRAST AGENTS History Definition Types RADIO - Contrast Agents MRI Contrast Agents US Contrast Agents Conclusion

HISTORY First contrast agent discovered: Barium solphate Initially mistaken for philosopher stone 1919: Heuser C. – use of contrast agent (Potassium Iodide) in living human circulatory system 1929: Swick M. – intravenous urograms. 1988: FDA declared Gadolinuim safe for MRI The birth of CA goes bak to the end of XIX century. All the compounds used were taken from chemistry studies and all efforts were to reduce their toxicity to safely inject them IV.

CONTRAST AGENTS History Definition Types RADIO - Contrast Agents 08/03/13 CONTRAST AGENTS History Definition Types RADIO - Contrast Agents MRI Contrast Agents US Contrast Agents Conclusion

Definition Contrast Agents Substances that help in better differentiation beetween adjacent tissues Positive (Iodinated contrasts) Increase visualization of a tissue Negative (Gases) Reduce visualization of a tissue

CONTRAST AGENTS History Definition Types RADIO - Contrast Agents 08/03/13 CONTRAST AGENTS History Definition Types RADIO - Contrast Agents MRI Contrast Agents US Contrast Agents Conclusion

TYPES RADIO-contrast agents (CT, X-RAYS) MRI contrast agents Iodine (IV) Barium sulfate (GI) MRI contrast agents Paramagnetic (Gadolinium-based) (IV) Superparamagnetic (USPIO, SPIO) (IV) Others (GI) US contrast agents (CEUS) Microbubbles (IV)

RADIO-contrast agents (CT, X-RAYS): IODINE Intra-venous: Iodine High Atomic Number (Z= 53) Per OS: Gastrografin (contains Iodine)

Contrast enhancement is critical The informed consent for using contrast is mandatory BEFORE the examination

Iodinated contrast agents ADVERSE REACTIONS Chemotoxic reactions (2-7%) Dose-dependent Mainly NEFROTOXIC EFFECTS Contrast Induced Nephropathy RISK FACTORS: CRF(GFR < 30 ml/min) Dehydration Cardiac Failure Metformin Ipertiroidism Risk of Thyrotoxic storm

Iodinated contrast agents ADVERSE REACTIONS Anaphylactoid reactions (1-2%) Dose-independent Mild: nausea, vomiting, flushing, flushing dizzyness, urticaria, pruritus Moderate: bronchospasm, dyspnea, chest pain, hypotension Severe(1/10.000): laryngeal edema, CPA, arrythmias Delayed (>1h) RISK FACTORS: Previous allergic reactions to Iodine Drug requiring allergies

RADIO-contrast agents (CT, X-RAYS): Barium Sulfate Exclusive use in GI imaging High attenuation coefficiency insoluble ADVERSE REACTIONS Chemical peritonitis(!) CONTRAINDICATIONS perforation suspected severe GI obstruction

MRI CONTRAST AGENTS Contrast Media 08/03/13 MRI CONTRAST AGENTS Contrast Media Paramagnetic or superparamagnetic substance Shorten relaxation times of surrounding protons Useful in T1-w sequences A Signal B TR Time

MRI CONTRAST AGENTS Gadolinium: 08/03/13 MRI CONTRAST AGENTS Gadolinium: Toxic in its free state - chelated to DTPA(Pentetic acid) Risks: - Systemic Nephrogenic Fibrosis Contraindicated when GFR<30ml/min - Acute adverse reactions Less frequent than with I-

CONTRAST AGENTS History Definition Types RADIO - Contrast Agents 08/03/13 CONTRAST AGENTS History Definition Types RADIO - Contrast Agents MRI Contrast Agents US Contrast Agents Conclusion

(contrast enhanced ultrasound) CEUS (contrast enhanced ultrasound) SonoVue ® Gas-filled microbubbles that are administered intravenously to the systemic circulation Intravenously administered Microbubble contrast agents for ultrasound are completely different from those used for either CT or MR scans Advantages: First, microbubbles for CEUS are purely intravascular, whereas CT or MR contrast agents can diffuse through the vascular endothelium into the interstitium Microbubble contrast agents are non-toxic and most patients are totally unaware of their injection CEUS is most effective when used for specific and well-designed indications in abdominal imaging. The major established application is for characterization of focal liver masses

CONCLUSION Contrast agents Useful, in some cases necessary Low intrinsic contrast of the tissue (ej cystography) Vascularized lesions (ej. HCC) Vessel evaluation (Angiography, Coronary catheterization, MRI) Potentially harmful Ask your radiology when in doubt

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