Podcast
Questions and Answers
Why is meticulous heparinization required during angiography when contrast media is mixed with blood?
Why is meticulous heparinization required during angiography when contrast media is mixed with blood?
- To enhance the tissue contrast
- To increase the echogenicity of blood
- To reduce the viscosity of the contrast media
- To prevent thromboembolic phenomenon (correct)
What is a characteristic of ultrasound contrast agents?
What is a characteristic of ultrasound contrast agents?
- They increase the echogenicity of tissues
- They are coated with shells of proteins, lipids, or synthetic polymers
- They are ideal for angiography studies
- They consist of microscopic gas-filled bubbles (correct)
What contributes to the extremely high reflectivity (backscatter) of ultrasound contrast agents?
What contributes to the extremely high reflectivity (backscatter) of ultrasound contrast agents?
- The viscosity of the contrast agent
- The speed of sound in the tissues
- Microbubbles changing their size during the ultrasonic cycle (correct)
- The frequency of ultrasound waves
Which generation of ultrasound contrast agents consists of longer-lasting bubbles coated with shells?
Which generation of ultrasound contrast agents consists of longer-lasting bubbles coated with shells?
What is the main reason first-generation ultrasound contrast agents are limited to cardiac and large vein studies?
What is the main reason first-generation ultrasound contrast agents are limited to cardiac and large vein studies?
What property allows microbubbles to resonate in the ultrasound beam?
What property allows microbubbles to resonate in the ultrasound beam?
What is the primary mechanism of signal enhancement for ultrasound contrast agents?
What is the primary mechanism of signal enhancement for ultrasound contrast agents?
Which characteristic is essential for an ideal ultrasound contrast agent?
Which characteristic is essential for an ideal ultrasound contrast agent?
Which type of microbubbles is formed by hand agitation?
Which type of microbubbles is formed by hand agitation?
What is the main reason for the instability of non-encapsulated microbubbles?
What is the main reason for the instability of non-encapsulated microbubbles?
Which Ultrasound Contrast Agent is ideal for liver, spleen, and lymph nodes?
Which Ultrasound Contrast Agent is ideal for liver, spleen, and lymph nodes?
What does the half-life or persistence of a microbubble depend on?
What does the half-life or persistence of a microbubble depend on?
What is the purpose of a contrast medium in radiography?
What is the purpose of a contrast medium in radiography?
What is the significance of using a substance with a high atomic number as a contrast medium?
What is the significance of using a substance with a high atomic number as a contrast medium?
Which type of study was first performed using Barium Sulphate as a contrast medium?
Which type of study was first performed using Barium Sulphate as a contrast medium?
What is a common side effect associated with contrast media?
What is a common side effect associated with contrast media?
Which of the following is NOT a common method for administering contrast media?
Which of the following is NOT a common method for administering contrast media?
What property of iodine made it the basis of all modern contrast agents?
What property of iodine made it the basis of all modern contrast agents?
Study Notes
Contrast Media Overview
- Contrast media is a chemical substance that increases or decreases the density of the organ under examination.
- Contrast depends on the absorption coefficients of different tissues.
History of Contrast Media
- 1896: Walter Bradford discovered contrast media.
- 1897: First reported GI contrast study performed using Bismuth, which was toxic.
- 1910: Barium Sulphate was used as a safer alternative.
- 1920s: Sodium Iodide was used to treat syphilis, and iodine was found to be radio-opaque to x-rays.
- 1927: First reported IVU with iodised organic salts (Uroselectan).
Ultrasound Contrast Agents (Echo Enhancers)
- Increase the echogenicity of blood, which heightens tissue contrast and allows better delineation of body cavities.
- Consist of microscopic gas-filled bubbles.
- High reflectivity arises from the fact that microbubbles easily change their size, contracting in compression and expanding in the rarefaction part of the ultrasonic cycle.
Generations of Echo Enhancers
- First generation: Unstabilized bubbles in indocyanine green, used only for cardiac and large vein studies.
- Second generation: Longer-lasting bubbles coated with shells of protein, lipids, or synthetic polymers.
- Third generation: Encapsulated emulsions or bubbles, offering high reflectivity.
Types of Ultrasound Agents
- Non-encapsulated microbubbles
- Encapsulated microbubbles:
- Encapsulated air microbubbles (e.g., Albunex, Echovist)
- Encapsulated perfluorcarbon microbubbles (e.g., Optison)
Ideal Ultrasound Contrast Agent
- Should be injectable by a peripheral vein
- Should be non-toxic
- Should be small enough to pass through pulmonary, cardiac, and capillary systems
- Should be stable enough to undergo shear forces, hydrostatic pressure changes, and diameter changes
- Should have a sufficient half-life to allow complete examination
- Should require little preparation
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Description
Learn about the characteristics and benefits of ultrasound contrast agents, also known as echo enhancing agents. Understand how these agents increase the echogenicity of blood to improve tissue contrast and delineation of body cavities. Explore their composition of microscopic gas-filled bubbles and high reflectivity from microbubbles.
