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Questions and Answers
What imaging technique is utilized when ERCP cannot be performed due to Billroth II surgery?
What imaging technique is utilized when ERCP cannot be performed due to Billroth II surgery?
Which type of contrast medium does not dissociate in water?
Which type of contrast medium does not dissociate in water?
What is a potential severe side effect of iodine-containing contrast media?
What is a potential severe side effect of iodine-containing contrast media?
What initial action should be taken for a patient experiencing urticaria after contrast media administration?
What initial action should be taken for a patient experiencing urticaria after contrast media administration?
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Which of the following side effects is considered an imminent sign of anaphylactic reaction?
Which of the following side effects is considered an imminent sign of anaphylactic reaction?
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How should a healthcare provider respond to bronchospasm in a patient experiencing side effects from contrast media?
How should a healthcare provider respond to bronchospasm in a patient experiencing side effects from contrast media?
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What characterizes hydrophilic contrast media?
What characterizes hydrophilic contrast media?
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Which statement about metformin is true?
Which statement about metformin is true?
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What is a potential consequence of administering iodine-containing contrast media to patients with impaired renal function?
What is a potential consequence of administering iodine-containing contrast media to patients with impaired renal function?
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Which of the following statements about metformin is TRUE?
Which of the following statements about metformin is TRUE?
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What blood pH level is indicative of lactic acidosis?
What blood pH level is indicative of lactic acidosis?
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What medication may be necessary for a patient with contraindicated renal function prior to receiving iodine-containing contrast media?
What medication may be necessary for a patient with contraindicated renal function prior to receiving iodine-containing contrast media?
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Which of the following is NOT a symptom of lactic acidosis?
Which of the following is NOT a symptom of lactic acidosis?
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For patients on metformin, when should the medication be stopped before receiving contrast media?
For patients on metformin, when should the medication be stopped before receiving contrast media?
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Which condition is considered an absolute contraindication for administering iodine-containing contrast media?
Which condition is considered an absolute contraindication for administering iodine-containing contrast media?
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What percentage represents the approximate mortality rate for untreated lactic acidosis?
What percentage represents the approximate mortality rate for untreated lactic acidosis?
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What is the primary purpose of using contrast media in imaging?
What is the primary purpose of using contrast media in imaging?
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Which of the following is a characteristic of positive contrast media?
Which of the following is a characteristic of positive contrast media?
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What is a potential side effect of ingesting barium-sulfate as a contrast media?
What is a potential side effect of ingesting barium-sulfate as a contrast media?
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What condition contraindicates the use of barium-sulfate?
What condition contraindicates the use of barium-sulfate?
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What is a distinguishing feature of negative contrast media?
What is a distinguishing feature of negative contrast media?
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Which of the following is a safe alternative to barium-sulfate when bowel perforation is suspected?
Which of the following is a safe alternative to barium-sulfate when bowel perforation is suspected?
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What should be checked if a pregnant woman receives iodine-containing contrast medium (CM)?
What should be checked if a pregnant woman receives iodine-containing contrast medium (CM)?
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In CT imaging, what term is used to describe materials that are less dense than the surrounding tissues?
In CT imaging, what term is used to describe materials that are less dense than the surrounding tissues?
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Why is cholecystography considered outdated?
Why is cholecystography considered outdated?
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How should breast feeding be managed after administration of iodine-containing CM?
How should breast feeding be managed after administration of iodine-containing CM?
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What is a key component of ultrasonic contrast medium (SonoVue)?
What is a key component of ultrasonic contrast medium (SonoVue)?
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What happens to ultrasonic microbubbles after they are injected into circulation?
What happens to ultrasonic microbubbles after they are injected into circulation?
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What is the typical diameter of ultrasonic microbubbles used in SonoVue?
What is the typical diameter of ultrasonic microbubbles used in SonoVue?
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Which statement about Gd-containing contrast medium (CM) is accurate?
Which statement about Gd-containing contrast medium (CM) is accurate?
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What special requirements are needed for using SonoVue effectively?
What special requirements are needed for using SonoVue effectively?
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What is a recommended action after administering a less stable Gd-containing CM to breastfeeding mothers?
What is a recommended action after administering a less stable Gd-containing CM to breastfeeding mothers?
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What action should be taken if the estimated glomerular filtration rate (eGFR) is below 30 ml/min/1.73 m²?
What action should be taken if the estimated glomerular filtration rate (eGFR) is below 30 ml/min/1.73 m²?
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Which of the following is NOT a symptom associated with lactic acidosis?
Which of the following is NOT a symptom associated with lactic acidosis?
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What is the recommended action regarding metformin administration prior to a study if the serum creatinine level is elevated?
What is the recommended action regarding metformin administration prior to a study if the serum creatinine level is elevated?
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What characteristic distinguishes paramagnetic contrast media from superparamagnetic contrast media in MR imaging?
What characteristic distinguishes paramagnetic contrast media from superparamagnetic contrast media in MR imaging?
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What is the mortality rate for lactic acidosis?
What is the mortality rate for lactic acidosis?
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Which of the following is a known use for lipiodol?
Which of the following is a known use for lipiodol?
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What components make up lipiodol?
What components make up lipiodol?
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Which statement regarding iron-oxide contrast media is true?
Which statement regarding iron-oxide contrast media is true?
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Study Notes
Contrast Media
- Contrast media are substances used to enhance the visibility of internal organs or tissues in medical imaging procedures such as X-rays and CT scans.
- They work by increasing the contrast between the organ of interest and its surroundings.
- Positive contrast media (e.g., barium sulfate, iodine) have high atomic numbers, attenuating X-rays more than surrounding structures, making those areas appear brighter in the image.
- Negative contrast media (e.g., air, CO2, methylcellulose solution) attenuate X-rays less than surrounding tissues, making those areas appear darker.
- Types of contrast media include iodine-containing (lipophilic and hydrophilic), barium sulfate, and ultrasonic contrast agents.
Contrast Media in Different Imaging Modalities
- X-ray Imaging: Air and fat show increased transparency, while bones, metals, and contrast media show decreased transparency.
- CT Imaging: Air and fat are less dense (hypodens), while bones, metals, and contrast media are hyperdens. Density differences highlight structures.
- MRI Imaging: Paramagnetic and superparamagnetic contrast media are used. Paramagnetic contrast increases T1 relaxation times, while superparamagnetic agents decrease T2 relaxation times.
Why Contrast Media Are Used
- To improve the contrast between anatomical structures (organs, tissues) in medical imaging procedures.
- Enhancing visualisation of structures with similar densities to aid diagnosis, e.g., differentiating a tumor from surrounding tissues.
Specific Contrast Media
- Barium sulfate: Insoluble, non-toxic when ingested, used in gastrointestinal studies (single or double contrast). Potential side effects include diarrhea. Contraindicated in suspected perforation. Alternatives include gastrografin (iodine-based).
- Iodine-containing contrast media: Used in various imaging procedures especially important for vessel visualisation. Lipophilic (e.g., in cholangiography) or hydrophilic (e.g., in intravenous angiography, CT, or MRI). Can have side effects like nausea, vomiting, allergic reactions, and kidney problems (if renal function is impaired). Contraindicated in patients with hyperthyroidism.
- Ultrasonic contrast agents (SonoVue): Microbubbles injected into vessels for assessing blood flow and visualizing focal liver lesions or kidney circulation.
Side Effects of Iodine-Containing Contrast Media
- Osmotic: The osmotic stress from contrast media can cause RBC deformation, potentially leading to thrombosis.
- Chemotoxic: Can cause nausea, vomiting, respiratory distress, and allergic reactions.
- Severe reactions: include hypotension, bronchospasm, and anaphylaxis; require immediate medical intervention.
Metformin and Contrast Media Interaction
- Metformin is an oral anti-diabetic drug frequently prescribed. It is cleared entirely by the kidneys.
- Impaired renal function can lead to metformin accumulation in the body, potentially causing lactic acidosis.
- Iodine-containing contrast media can temporarily further impair renal function in patients with pre-existing reduced eGFR.
- Pre-examination testing, including serum creatinine and eGFR levels, is critical for evaluating patients on metformin in relation to contrast media administration.
Further Contraindications for Contrast Media Use
- Manifest hyperthyroidism requires physician notification.
- Myeloma multiplex can worsen with contrast.
- Pheochromocytoma needs prior administration of alpha and beta blockers.
- Pregnancy is usually a contraindication.
Lactic Acidosis
- Serious metabolic complication in diabetic patients, resulting from the accumulation of lactate.
- Characterized by blood pH below 7.25 and lactate levels above 2.5 mmol/
- Symptoms range from gastrointestinal distress to muscle pain, metabolic crises, and coma.
- Treatment includes bicarbonate infusion to correct acidosis and dialysis to remove excess lactate.
Additional Notes
- Patients with various medical conditions or allergies should inform their physicians about their medical history prior to medical imaging.
- Patients on metformin must discuss concerns about contrast media with their physician.
- Contraindications vary by type of contrast medium and procedure.
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Description
This quiz explores the role of contrast media in enhancing medical imaging techniques such as X-rays and CT scans. Learn about different types of contrast agents, how they work, and their effects on visibility in imaging procedures. Test your knowledge on both positive and negative contrast media.
