Contrast medium的意思
"Contrast medium" or "contrast agent" refers to a substance used in medical imaging procedures to enhance the visibility of certain bodily structures or organs. These substances are typically administered intravenously, orally, or by injection into the body part being imaged. The contrast medium helps to delineate the anatomy and can reveal abnormalities or pathologies that may not be visible without it.
There are two main types of contrast media:
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Ionic contrast media: These were the first contrast agents developed and are composed of charged molecules. They are less commonly used today due to their potential for causing side effects.
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Non-ionic contrast media: These are newer agents that have replaced ionic contrast media in many clinical settings. They are composed of uncharged molecules and are generally associated with fewer side effects.
Contrast media are used in various imaging modalities, including:
- X-ray (for example, in angiography to visualize blood vessels)
- Computed tomography (CT) scans (to improve the detail of internal organs and tissues)
- Magnetic resonance imaging (MRI) (although MRI contrast agents are different from those used in CT and X-ray and are based on their ability to interact with the magnetic fields used in MRI)
- Ultrasound (contrast agents for ultrasound are usually microbubbles that help in the imaging of blood flow)
The choice of contrast medium depends on the specific imaging technique, the part of the body being examined, and the patient's medical history and any allergies they may have to certain agents.