X-ray examinations of Gastrointestinal Tract Part I Flashcards
What are the primary functions of contrast media in imaging?
Contrast media improve the visibility of organs, body parts, or systems by enhancing the contrast between structures and surrounding tissues that are not typically visualized on plain radiographs.
List the routes through which contrast media can be administered.
Oral: Swallowing the contrast agent.
Intravenous/Intra-arterial: Injection into blood vessels.
Rectal: Administered through an enema.
What are the six key attributes of an ideal contrast medium?
- Easy to administer.
- Minimally unpleasant to the patient.
- Non-toxic.
- Stable compound.
- Rapid elimination from the body.
- Non-carcinogenic with appropriate viscosity.
How are radiographic contrast media classified?
Positive Contrast Media: Radiopaque, attenuates X-rays more, appears whitish on images (e.g., barium sulfate, iodine compounds).
Negative Contrast Media: Radiolucent, attenuates X-rays less, appears black on images (e.g., air, carbon dioxide).
Differentiate between ionic and non-ionic iodine-based contrast media.
Ionic: Dissociate into ions, water-soluble, higher toxicity (e.g., Diatrizoate, Iothalamate).
Non-ionic: Do not dissociate, water-soluble due to polar OH groups, lower toxicity (e.g., Iohexol, Iopamidol).
Why are iodine compounds preferred as contrast agents?
Due to their low toxicity, excellent radio-opacity, and ability to dissolve in water for versatile use in various procedures.
What are the potential side effects or reactions to contrast media?
Mild Reactions: Nausea, itching, or warmth.
Moderate Reactions: Urticaria, vomiting, or bronchospasm.
Severe Reactions: Anaphylactic shock, cardiac arrest, or convulsions (rare).
What precautions must be taken before administering contrast media?
Check the patient’s history for allergies to contrast, food, or drugs.
Verify medical conditions like asthma, diabetes, or kidney disease.
Ensure emergency drugs are available in case of adverse reactions.
What two basic rules should radiographers follow when administering contrast media?
Emergency drugs for allergic reactions must be readily available.
Patients must not be left unattended until the examination is complete.
How are contrast media side effects classified?
By Severity: Mild, moderate, and severe reactions.
By Mechanism of Reaction: Allergic-type or toxic effects.
What are the characteristics of positive contrast media?
High atomic number.
Radiopaque (absorbs more X-rays).
Appears whitish against soft tissues.
Examples include barium sulfate and iodine compounds.
What are the characteristics of negative contrast media?
Low atomic number.
Radiolucent (absorbs fewer X-rays).
Appears dark or black on radiographs.
Examples include air and carbon dioxide.
What are the benefits of non-ionic iodine-based contrast agents compared to ionic ones?
- Lower toxicity.
- Reduced side effects.
- Suitable for patients with higher risk factors.
Why is it important to assess a patient’s medical history before administering contrast media?
Certain conditions (e.g., asthma, thyroid problems, or kidney disease) may increase the risk of adverse reactions and require careful monitoring.
How should a radiology department prepare for potential adverse reactions to contrast media?
- Equip the department with emergency drugs and resuscitation equipment.
- Train staff to recognize and respond to adverse reactions promptly.
