BASIC PHARMACOLOGY: CONTRAST MEDIA

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Questions and Answers

What is the position of the iodine atoms on the benzene ring?

Position 1, 3, 5

Position 1, 2, 3

Position 2, 4, 6 (correct)

Position 3, 5, 7

What is the function of iodine molecules in ROCM?

To reduce the osmolality of the media

To allow more photons to pass through the body

To increase the solubility of the media

To increase the radiopacity of the media (correct)

What determines the radiopacity of ROCM?

The percentage of iodine in the molecule (correct)

The osmolality of the media

The type of cation used

The concentration of the media

What is osmosis?

The movement of water across a semipermeable membrane Signup and view all the answers

What is the result of placing a highly osmotic agent into the bloodstream?

Fluid from outside the bloodstream is drawn into the bloodstream. Signup and view all the answers

What is required for osmosis to occur?

A greater concentration of solute on one side of the membrane Signup and view all the answers

What is the effect of osmotically active particles on the intravascular space?

Dilution of normal intravascular constituents. Signup and view all the answers

What is the unit of measurement for osmolality?

Milliosmoles per kilogram (mOsm/kg) Signup and view all the answers

What is the purpose of osmosis in a solution?

To equilibrate osmotic pressures between two permeable or semipermeable membranes. Signup and view all the answers

What is osmolality?

The concentration of molecules per kilogram of water Signup and view all the answers

What is osmolarity?

The concentration of molecules per liter of solution Signup and view all the answers

What is the effect of highly osmotic agents on the intravascular and extravascular spaces?

Osmotic pressures are equilibrated between the two spaces. Signup and view all the answers

What is the term for the number of molecules per liter of solution?

Osmolarity. Signup and view all the answers

What is the effect of highly osmotic agents on cardiac function?

Contributes to adverse cardiac effects. Signup and view all the answers

What is the term for the movement of water from an area of high concentration to an area of low concentration?

Osmosis. Signup and view all the answers

What is the effect of highly osmotic agents on the kidneys?

Contributes to adverse renal effects. Signup and view all the answers

What percentage of ROCM may be eliminated via the hepatic-biliary system?

Up to 50% Signup and view all the answers

Which IV ROCM is eliminated principally by the hepatic-biliary system?

Iodamide meglumine Signup and view all the answers

What is the primary function of enteral radiopaque contrast media?

To diagnose and evaluate disorders of the GI system Signup and view all the answers

What is the category of Gastrografin?

Aqueous solution Signup and view all the answers

Why is Gastrografin preferred over barium sulfate for CT scans?

Less artefact production Signup and view all the answers

What is a potential adverse effect of using Gastrografin?

Diarrhea and systemic hypovolemia Signup and view all the answers

How long does it take for radiopacity to occur in the duodenum after oral administration of Gastrografin?

15 to 90 minutes Signup and view all the answers

How are gastrointestinal ROCM distributed in the body?

Solely into the GI lumen Signup and view all the answers

What is measured in Magnetic Resonance Imaging (MRI)?

Return of transiently excited protons Signup and view all the answers

What reduces both longitudinal and transverse relaxation times of nearby water protons?

Paramagnetic contrast agents Signup and view all the answers

What is the result of using paramagnetic contrast agents in MRI?

Enhanced image when exposed to a strong magnetic field Signup and view all the answers

Which of the following is NOT a gadolinium compound?

Gadolinium sulfate Signup and view all the answers

Where do gadolinium compounds rapidly distribute?

Intracellular and extravascular spaces Signup and view all the answers

What is the osmolality of gadolinium compounds?

Approximately 1960 mOsm/kg H2O Signup and view all the answers

What is the advantage of using contrast agents in MRI?

Increased conspicuity of lesions Signup and view all the answers

What is the result of contrast agent administration in the post-contrast image?

Rim enhancement of the lesion Signup and view all the answers

What is the primary use of Gadopentetate salts in medical imaging?

Visualizing central nervous system lesions Signup and view all the answers

What is a characteristic of Iron Compounds used as contrast agents?

Low osmolality Signup and view all the answers

What is the primary use of Mangafodipir trisodium (Teslascan) in medical imaging?

Visualizing hepatic lesions with hepatocytes Signup and view all the answers

What type of lesions can Gadopentetate salts help identify?

Central nervous system lesions, including spinal neoplasms and pituitary adenoma Signup and view all the answers

What is a potential use of Gadopentetate salts in MRI?

Enhancing resolution in obese individuals Signup and view all the answers

What type of tissues do Iron Compounds help identify lesions in?

Hepatic and lymphatic tissues Signup and view all the answers

Study Notes

Contrast Media

Iodine molecules are effective photon absorbers in the human body, blocking photons from passing through to radiographic film, resulting in radiopacity.
Radiopacity is a direct function of the percentage of iodine in the molecule and the concentration of media present.

Osmolality, Osmolarity, and Osmotic Activity

Osmosis is the movement of water across a semipermeable membrane, requiring a greater concentration of solute on one side to draw water across the membrane.
Osmolality is the number of milliosmoles per kilogram of water, measuring the concentration of molecules per weight of water, with units in mol/kg.
Osmolarity is the number of milliosmoles per liter of solution, measuring the concentration of molecules per liter of solution, with units in mOsm/L.

Osmotically Active Particles

Highly osmotic agents, such as ROCM, attract water, causing a dilutional effect to equilibrate pressures between two permeable or semipermeable membranes.
ROCM in the bloodstream causes fluid from outside the bloodstream to be drawn into the bloodstream, diluting osmotic particles and increasing intravascular hydrostatic pressures.

Enteral Radiopaques Contrast Media

Used to diagnose and evaluate disorders of the GI system.
Categories include aqueous solutions, suspensions, and tablets.
Examples include diatrizoate meglumine and diatrizoate sodium (Gastrografin) solutions, which aid in the diagnosis of GI tract disorders.

Paramagnetic Contrast Agents

Consist of heavy metal chelates, such as gadolinium, iron, and manganese, that reduce the longitudinal and transverse relaxation times of nearby water protons in MRI scans.
Enhance image production in MRI scans.

Gadolinium Compounds

Rapidly distribute into intracellular and extravascular spaces.
Examples include gadodiamide (Omniscan), gadoteridol (ProHance, gadoversetamide OptiMARK), gadobutrol (Gadovist), and gadopentetate dimeglumine (Magnevist).
Useful in identifying central nervous system lesions, spinal neoplasms, spinal disease, primary brain tumors, intracranial metastases, acoustic neurinomas, active multiple sclerosis, pituitary adenoma, and meningeal disease.

Iron Compounds

Ferumores contain iron particles that are highly paramagnetic and remain in the bloodstream for long periods.
Examples include ferumoxtran-10 (Combidex), iron oxide (Clariscan), and ferumoxytol.
Useful in identifying hepatic lesions and lesions associated with lymphatic tissues.

Manganese Compounds

Mangafodipir trisodium (Teslascan) is a compound containing manganese, used primarily to identify cancers that have hepatocytes in their matrix.

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Description

This quiz covers the basics of contrast media in pharmacology, including the structure and properties of iodinated molecules used in medical imaging.