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CTA for GI Bleed

Last Updated: 2026-01-05
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  • 1. Clinical Summary

    Series Phase Coverage
    Non-contrast Non-contrast Diaphragm to Pubic symphysis
    Arterial Phase Contrast (25 sec delay) Diaphragm to Pubic symphysis
    Delayed Phase Contrast (90 sec delay) Diaphragm to Pubic symphysis
    • Active GI bleeding
    • Hematemesis
    • Melena with hemodynamic instability
    • Hematochezia

  • 2. Patient Prep

    • Position: Supine with arms raised
    • NPO Status: NPO if possible (emergent study)

  • 3. IV Contrast & Injection

    Parameter Value
    Agent Isovue 370
    Volume 1.5 mL/kg
    Flow Rate 4-5 mL/s
    Duration 20s
    Timing Method Triple phase: Arterial + Portal Venous + Delayed
    ROI Placement Abdominal aorta
    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

    • High flow rate critical for arterial phase. Scan arterial at 25 sec then portal at 70 sec then delayed at 90-180 sec. Look for active extravasation
    • Additional Recons: MIP of all three phases side-by-side for comparison
    • Large bore IV 18-20G essential. Verify with saline test

    Safety First

    • Renal Function: eGFR > 30 preferred but can proceed emergently
    • Allergy: Document allergy history. Emergency indication overrides mild allergy
    • Look for arterial extravasation (early) and pooling (delayed). Note location and potential source vessel
    • Arms raised to avoid artifacts. Fast table speed to cover area quickly in arterial phase
Series Name Start Location End Location Delay Slice Thickness Notes
Scout/Topogram Diaphragm Pubic symphysis N/A N/A AP scout
Arterial Phase Diaphragm Pubic symphysis 25 sec 0.625 mm High flow rate 5 mL/s critical
Delayed Phase Diaphragm Pubic symphysis 90 sec 0.625 mm Extended delay to see pooling of contrast
Plane Acquisition FOV Thickness/Increment Kernel IR Strength Notes
Axial Arterial Full AP 2.5 mm/2.5 mm Standard 3 Look for arterial blush/extravasation
Axial Delayed Full AP 2.5 mm/2.5 mm Standard 3 Look for contrast pooling in bowel
Coronal All phases Full AP 3 mm/3 mm Standard 3 MIP to track extravasation