Contrast Media and Pharmacology Flashcards

Which class of iodinated contrast media has the lowest osmolality and is considered safest for intravascular administration, especially in high-risk patients?

Answer: Nonionic iso-osmolar contrast media

Nonionic iso-osmolar contrast agents (e.g., iodixanol) have an osmolality equal to blood (~290 mOsm/kg) and are associated with the lowest risk of adverse reactions.

A patient receiving iodinated IV contrast suddenly develops generalized urticaria, bronchospasm, and hypotension. This reaction is classified as:

Answer: Anaphylactoid (anaphylaxis-like) reaction

Generalized urticaria combined with bronchospasm and hypotension constitutes a severe anaphylactoid reaction, which requires immediate emergency treatment with epinephrine.

The most important risk factor for contrast-induced acute kidney injury (CI-AKI) following IV iodinated contrast administration is:

Answer: Pre-existing renal insufficiency (elevated serum creatinine/reduced eGFR)

Pre-existing renal insufficiency (eGFR <30–45 mL/min/1.73m²) is the most significant risk factor for contrast-induced acute kidney injury.

Barium sulfate is the preferred contrast agent for gastrointestinal studies when aspiration is NOT a concern because:

Answer: It provides superior mucosal coating and image quality compared to water-soluble agents

Barium sulfate provides excellent mucosal coating for double-contrast GI studies, giving superior visualization of the mucosal surface compared to water-soluble contrast.

Which route of contrast administration requires the highest iodine concentration for adequate opacification in CT imaging?

Answer: Intravenous (IV) injection

IV contrast requires high iodine concentration (e.g., 300–370 mgI/mL) because it is diluted by blood volume before reaching target tissues; oral and intrathecal contrast use much lower concentrations.

A patient reports a previous moderate contrast reaction. What is the standard premedication protocol to reduce risk of a repeat reaction?

Answer: Prednisone 50 mg orally at 13 hours, 7 hours, and 1 hour before contrast plus diphenhydramine 50 mg IM/IV 1 hour before

The standard ACR premedication protocol for prior contrast reaction uses oral prednisone at 13h, 7h, and 1h before contrast, plus diphenhydramine 1h before — corticosteroids reduce reaction severity.