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CT Parathyroid 4D

Last Updated: 2026-01-01 Author:

  • 1. Clinical Summary

    Series Phase Coverage
    Non-Contrast Non-contrast Skull base to Carina
    Arterial Phase Contrast (25 sec delay) Skull base to Carina
    Venous Phase Contrast (55 sec delay) Skull base to Carina
    Delayed Phase Contrast (90 sec delay) Skull base to Carina
    • Hyperparathyroidism
    • Parathyroid adenoma localization
    • Pre-operative parathyroid planning

  • 2. Patient Prep

    • Position: Supine head-first with arms down
    • NPO Status: NPO 4 hours

  • 3. IV Contrast & Injection

    Parameter Value
    Agent Omnipaque 350
    Volume 75-100 mL
    Flow Rate 4 mL/s
    Timing Method 4D multi-phase
    ROI Placement Carotid artery
    Trigger (HU) 150 HU

    Use full dose if GFR > 30

    If GFR < 30

    Max Contrast = \(2*\left[\frac{\text{Patient Weight}}{75 \text{ kg}} * \text{eGFR}\right]\)

  • 4. Special Notes

    • FOUR phases: 1) NC 2) Arterial 25s 3) Venous 55s 4) Delayed/washout 90s. Skull base to mediastinum. Parathyroid enhances early washes out
    • Additional Recons: Subtraction images. Compare all phases. Document location for surgeon. Measure size
    • 18-20G IV. High flow rate for arterial

    Safety First

    • Renal Function: Verify eGFR > 30
    • Allergy: Check allergy history
    • NC: baseline. Arterial: parathyroid lights up. Venous: thyroid enhances. Delayed: parathyroid washes out faster than thyroid
    • Four phase critical. Look for early enhancement and washout
Series Name Start Location End Location Delay Slice Thickness Notes
Scout Skull base Carina N/A N/A AP lateral
Non-Contrast Skull base Carina N/A 2.5 mm Baseline
Arterial Phase Skull base Carina 25 sec 2 mm Parathyroid enhancement
Venous Phase Skull base Carina 55 sec 2 mm Thyroid enhancement
Delayed Phase Skull base Carina 90 sec 2.5 mm Washout phase
Plane Acquisition FOV Thickness/Increment Kernel IR Strength Notes
Axial All phases Neck 2 mm/2 mm Standard 3 Compare all four phases
Axial Arterial Neck 2 mm/2 mm Standard 3 Peak parathyroid enhancement
Subtraction Arterial - NC Neck 2 mm Standard 3 Enhance parathyroid conspicuity
Coronal Arterial Neck 2.5 mm Standard 3 Ectopic adenoma search