What is the recommended dosing of Visipaque (iodixanol) contrast for a computed tomography (CT) neck scan?

Visipaque (Iodixanol) Dosing for CT Neck

For CT neck imaging in adults, administer 100 mL of iodixanol at 320 mg iodine/mL (Visipaque 652 mg/mL) via power injector at 2 mL/s injection rate, with scanning initiated after a 35-second delay. 1, 2

Standard Dosing Protocol

Volume and Concentration:

• Adults and pediatric patients ≥12 years: Use 320 mg iodine/mL concentration for CT imaging of the head and body 1
• Pediatric patients <12 years: Use 270 mg iodine/mL concentration for CT imaging of the head and body 1
• Maximum total iodine dose in adults: 80 grams 1

Injection Parameters:

• Optimal injection rate: 2 mL/s provides the longest duration of adequate vascular enhancement (27±4 seconds) for head and neck imaging 2
• Scan delay: 35 seconds after contrast injection initiation ensures optimal arterial and venous enhancement 2
• Lower injection rates (1.5 mL/s) result in insufficient venous enhancement and should be avoided 2
• Higher rates (3-4 mL/s) do not provide additional benefit for neck imaging 2

Clinical Context for Contrast Use

Intravenous contrast should always be used for CT neck unless contraindicated 3. The American Academy of Otolaryngology-Head and Neck Surgery strongly recommends contrast administration because it:

• Improves characterization of masses (distinguishing cystic from solid lesions) 3
• Maps lesion borders more accurately 3
• Improves identification of small primary sites in the upper aerodigestive tract 3
• Increases sensitivity for detecting metastatic adenopathy 3

Avoid ordering CT with and without contrast as this doubles radiation exposure with minimal added diagnostic benefit 3

Contraindications and Precautions

Absolute contraindications:

• Intrathecal use (can cause death, seizures, cerebral hemorrhage, coma, paralysis) 1

Relative contraindications requiring dose modification or alternative imaging:

• Contrast allergy 3, 1
• Renal insufficiency (risk of contrast-induced acute kidney injury) 3, 1
• Prior diagnosis that excludes contrast use 3

Hydration is mandatory: Patients must be adequately hydrated before and after intravascular iodinated contrast administration to minimize nephrotoxicity risk 1

Special Populations

Pediatric patients 0-3 years:

• Individualize thyroid function monitoring based on risk factors such as prematurity, as iodinated contrast can cause thyroid dysfunction 1

Geriatric patients:

• Exercise caution in dose selection due to increased risk of renal impairment 1

Lactating women:

• May pump and discard breast milk for 10 hours after iodixanol administration 1

Technical Considerations

Automated injection systems:

• Iodixanol may be administered using automated contrast injection systems or contrast media management systems cleared for use with this agent 1

Alternative low-dose protocols:

• In select cases, 270 mg iodine/mL concentration can provide diagnostic quality images with reduced iodine load (15.6% reduction) while maintaining adequate enhancement 4
• However, the standard 320 mg iodine/mL concentration remains preferred for comprehensive neck evaluation 1

Common Pitfalls to Avoid

• Do not use injection rates below 2 mL/s as this results in inadequate venous enhancement during the scan acquisition window 2
• Do not skip hydration protocols as this significantly increases nephrotoxicity risk, particularly in patients with baseline renal impairment 1
• Do not order both non-contrast and contrast studies unless there is a specific clinical indication, as this doubles radiation exposure without meaningful diagnostic gain 3
• Do not exceed 80 grams total iodine dose in adult patients 1