CT Contrast Media and Patient Preparation Flashcards
6 cards from real Computed Tomography Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CT Contrast Media and Patient Preparation flashcards as text
What is the standard iodine concentration range (in mg I/mL) for contrast agents commonly used in diagnostic CT?
Answer: 300–370 mg I/mL
Most CT contrast agents contain 300–370 mg I/mL; higher concentrations improve vascular opacification while lower volumes can be used to reduce total iodine load.
Which intravenous catheter gauge is recommended for power injection during contrast-enhanced CT?
Answer: 18–20 gauge
An 18–20 gauge IV catheter is recommended for power injection; smaller gauges risk rupture at high flow rates, while larger gauges are unnecessary.
A thyroid cancer patient requires radioiodine ablation therapy. Why must iodinated CT contrast be avoided before this treatment?
Answer: Iodinated contrast saturates the sodium-iodide symporter, blocking therapeutic radioiodine uptake
Excess stable iodine from contrast saturates thyroid transporters and competes with therapeutic I-131, significantly reducing radioiodine ablation efficacy for 2–8 weeks.
What is the primary advantage of using saline flush after contrast injection in CT?
Answer: Pushes residual contrast into central circulation, improving vascular opacification and reducing dose
A 30–50 mL saline chaser propels contrast remaining in the IV tubing and peripheral vein into the bloodstream, maximizing the usable contrast bolus.
Which pre-medication regimen is typically used for patients with prior moderate contrast reactions undergoing non-emergent contrast CT?
Answer: Oral prednisone 13 hours, 7 hours, and 1 hour before, plus diphenhydramine 1 hour before
The standard ACR-recommended steroid premedication protocol uses oral prednisone at three intervals before the scan combined with antihistamine to reduce breakthrough reaction risk.
Dual-energy CT (DECT) can be used to create virtual non-contrast (VNC) images. What does this eliminate for the patient?
Answer: The need for a separate pre-contrast CT acquisition
VNC images derived from DECT data simulate non-contrast images by mathematically subtracting iodine signal, eliminating a dedicated unenhanced acquisition and reducing dose.