Computed Tomography Test CT Contrast Media and Patient Preparation

Question 1

What is the most common type of iodinated contrast media used for CT examinations?

Accepted Answer

Non-ionic, water-soluble iodinated contrast

Answer

Non-ionic, water-soluble iodinated contrast agents are preferred for CT because they have lower osmolality and fewer adverse reactions compared to ionic agents.

Question 2

Which serum creatinine-based calculation is most commonly used to screen for contrast-induced nephropathy risk before CT?

Accepted Answer

eGFR (estimated Glomerular Filtration Rate)

Answer

eGFR calculated from serum creatinine is the standard screening tool; an eGFR <30 mL/min/1.73m² generally indicates high risk for contrast nephrotoxicity.

Question 3

At what injection rate (mL/sec) is intravenous contrast typically administered for a CT pulmonary angiography (CTPA)?

Accepted Answer

3–5 mL/sec

Answer

CTPA requires a brisk injection rate of 3–5 mL/sec to achieve adequate pulmonary artery opacification during the brief arterial phase.

Question 4

Which medication must be withheld 48 hours before and after iodinated contrast administration in patients with renal impairment?

Accepted Answer

Metformin

Answer

Metformin must be withheld because contrast-induced nephropathy can impair its renal clearance, leading to toxic accumulation and risk of lactic acidosis.

Question 5

What is the typical oral contrast agent used to opacify the GI tract during abdominal CT?

Accepted Answer

Dilute barium or water-soluble iodinated contrast

Answer

Dilute barium sulfate or water-soluble iodinated contrast is given orally to distend and opacify the bowel, distinguishing it from adjacent pathology.

Computed Tomography Test Practice Test

Computed Tomography Test Practice Test

Computed Tomography Test CT Contrast Media and Patient Preparation