Contrast Media and Pharmacology Flashcards

Which of the following patients is most likely to require alternative contrast or modified protocol due to risk of gadolinium-related nephrogenic systemic fibrosis (NSF)?

Answer: Patient with eGFR 25 mL/min/1.73m² on dialysis

NSF occurs almost exclusively in patients with severe renal failure (eGFR <30) receiving certain gadolinium-based contrast agents; patients on dialysis are at highest risk.

A patient develops a vasovagal reaction during contrast injection, presenting with bradycardia, hypotension, pallor, and diaphoresis. The appropriate initial treatment is:

Answer: Positioning supine with legs elevated, IV fluid bolus, and atropine if bradycardia persists

Vasovagal reactions are treated with Trendelenburg positioning (legs up, head down), IV fluid bolus to increase venous return, and atropine 0.6–1.0 mg IV for symptomatic bradycardia.

Air is used as a negative contrast agent for which type of gastrointestinal study?

Answer: Double-contrast barium enema (BE) or upper GI series

Air serves as a negative contrast agent (radiolucent) alongside positive barium sulfate in double-contrast studies of the GI tract, providing mucosal detail.

The standard power injector flow rate for CT pulmonary angiography (CTPA) to adequately opacify the pulmonary arteries is typically:

Answer: 4–5 mL/second

CTPA requires a flow rate of 4–5 mL/second to achieve adequate opacification of the pulmonary arteries for PE detection; slower rates result in suboptimal enhancement.

Which iodinated contrast agent is specifically approved for intrathecal (subarachnoid) administration in myelography?

Answer: Iohexol (Omnipaque)

Iohexol (Omnipaque) is the most widely used and specifically FDA-approved nonionic, water-soluble contrast agent for intrathecal administration in myelography.

According to ACR guidelines, patients taking metformin for type 2 diabetes who receive IV iodinated contrast should:

Answer: Hold metformin for 48 hours after contrast if eGFR is 30–60 mL/min/1.73m², and resume only after re-checking renal function

ACR guidelines recommend holding metformin for 48 hours after contrast in patients with eGFR 30–60 due to the risk of lactic acidosis if contrast causes renal impairment and metformin accumulates.