Omnipaque Dosing for CT Neck
The provided evidence does not contain specific dosing recommendations for CT neck imaging with Omnipaque (iohexol), as all guideline references address iohexol plasma clearance measurement protocols for GFR assessment, not diagnostic CT imaging protocols.
Critical Context Issue
The available evidence exclusively discusses:
- Iohexol administration for measuring glomerular filtration rate (GFR), which uses standardized small volumes (5 mL of Omnipaque 300, containing 3235 mg iohexol total) for pharmacokinetic blood sampling 1
- Laboratory calibration procedures for iohexol assays 2
- Contrast allergy management unrelated to dosing 3
These protocols are fundamentally different from diagnostic CT imaging, where contrast volumes are substantially larger and weight-based.
Standard CT Neck Dosing (General Medical Knowledge)
For CT neck angiography with Omnipaque, typical dosing is:
- Volume: 75-100 mL of Omnipaque 300 or 350
- Injection rate: 3-5 mL/second
- Total iodine load: Approximately 300-350 mg iodine/kg body weight
- Timing: 25-30 second delay for arterial phase imaging
For CT neck soft tissue (non-angiographic):
- Volume: 100-150 mL of Omnipaque 300 or 350
- Injection rate: 1-3 mL/second
- Timing: 60-90 second delay for venous phase
Available Omnipaque Concentrations
The following preparations exist, though their use in GFR measurement differs from CT imaging 1:
| Concentration | Iohexol (mg/mL) | Typical CT Application |
|---|---|---|
| Omnipaque 350 | 755 | Preferred for vascular imaging |
| Omnipaque 300 | 647 | Standard for most CT applications |
| Omnipaque 240 | 518 | Lower osmolality option |
Important Safety Considerations
- Renal function assessment is mandatory before contrast administration, as iohexol elimination half-life extends from ~2 hours (normal GFR) to 23-27 hours in severe renal impairment 4
- Seven-day washout period is required if patient had prior iodinated contrast exposure 1
- Hydration status matters, as volume contraction can affect contrast distribution and renal tolerance 1
Critical Pitfall
Do not use the 5 mL GFR measurement dose (3235 mg total iohexol) for diagnostic CT neck imaging 1—this dose is 20-30 times smaller than required for adequate vascular or soft tissue enhancement and will result in non-diagnostic images.