CT Imaging Artifacts and Contrast Agents

Introduction to Contrast Agents

The choice of contrast agent is crucial in CT imaging, with barium and water-soluble contrast being two commonly used options, each with its own advantages and disadvantages, as noted by the American College of Radiology 1, 2

Barium creates significant streak artifacts that can interfere with CT image interpretation, particularly in areas adjacent to barium-containing bowel loops, which can obscure important findings and potentially hide small lesions or subtle abnormalities, as reported by the American College of Radiology 1, 2
The American College of Radiology notes that barium can interfere with subsequent CT imaging due to streak artifact, and in colorectal cancer screening contexts, prior barium studies can complicate CT colonography interpretation, with the ACR Appropriateness Criteria indicating that barium studies are no longer justified as backup examinations for incomplete colonoscopy 1, 2

Water-soluble contrast causes less streak artifact on CT compared to barium, and permits immediate follow-up colonoscopy with no delay, whereas barium must be cleared from the colon before endoscopic procedures, delaying colonoscopy, as recommended by the American College of Radiology 2, 3
Water-soluble contrast is significantly safer than barium if perforation occurs, preventing barium peritonitis, and is also safer if aspirated into the lungs, as it is less hazardous if aspiration occurs, according to the American College of Radiology and the World Journal of Emergency Surgery 3, 4, 2

Barium is extremely dangerous if perforation is present, causing barium peritonitis, and can cause severe chemical pneumonitis if aspirated into lungs, posing a hazardous risk if aspirated, as reported by the American College of Radiology 2, 3
Barium may worsen partial small bowel obstruction, converting it to complete obstruction, and water-soluble contrast can cause serious fluid shifts due to high osmolarity, drawing fluid into the bowel lumen, and may further dehydrate patients with small bowel obstruction, posing a potential dehydration risk 3, 4
Rare anaphylactoid reactions have been reported with water-soluble contrast, though they are uncommon, and should be used with caution in patients with high risk of gastropathy, as noted by the American College of Radiology 4

The American College of Radiology recommends ensuring adequate decompression through nasogastric tube before administering contrast, and providing adequate hydration before giving water-soluble contrast, with the recommended dosing of Gastrografin being 50-150 ml, either orally or via nasogastric tube 4
Gastrografin can be given at admission or after 48 hours of conservative treatment, with consideration of the timing of contrast administration, and should be used with caution in patients with high risk of gastropathy, as recommended by the American College of Radiology 4