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Coronary CTA Post-CABG

Last Updated: 2026-02-02
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  • 1. Clinical Summary

    Series Phase Coverage
    Calcium Score Non-contrast Lung apices to Diaphragm
    Gated CTA Arterial (bolus tracked) Lung apices to Diaphragm
    • Post-CABG graft patency assessment
    • Recurrent chest pain post-bypass

  • 2. Patient Prep

    • Position: Supine feet-first
    • NPO Status: NPO 2-4 hours
    • Pre-Medication:
      • HR < 60 target.
      • Metoprolol 5mg IV increments up to 15mg. Metoprolol contraindications include sBP < 100, 2nd/3rd degree heart block, and inhaler dependent asthma.
      • Nitroglycerin 0.4mg SL 5 minutes before scan. Nitroglycerin contraindications include sBP < 100, PDE5 inhibitors within 48 hrs, severe aortic stenosis.

  • 3. IV Contrast & Injection

    Parameter Value
    Agent Isovue 370
    Volume 1.1 mL/kg
    Flow Rate 4-5 mL/s
    Duration 18s
    Timing Method Bolus Tracking
    ROI Placement Ascending aorta
    Trigger (HU) 200 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

    • Non-valsalva breathing technique, cardiac breathing instruction. Put in study notes if patient unable to follow breathing instructions.
    • If high HR variability, can trigger by millisecond (200ms - 450 ms pulse range). Revolution CT is better for Afib.
    • Target End diastole if HR < 65bpm. Target End systole if HR > 86bpm. Target End diastole to End systole if HR 66 - 75 bpm
    • Additional Recons: Curved MPR of all grafts. Label LIMA RIMA SVG.
    • 20G IV minimum. Check for metoprolol or nitroglycerin contraindications. Nitro is priority over metoprolol if BP is borderline.

    Safety First

    • Renal Function: Verify eGFR > 30
    • Allergy: Check allergy history
    • Assess all grafts: LIMA RIMA SVG. Check anastomoses. Native vessel disease. Graft patency vs occlusion. Check functional series for WMA.
    • Full chest coverage essential. Extended FOV. Low pitch for retrospective gating
Series Name Start Location End Location Delay Slice Thickness Notes
Scout Thoracic inlet Below heart N/A N/A AP lateral
Calcium Score Lung apices Diaphragm N/A 1.5 mm Calcium score
Gated CTA Lung apices Diaphragm Bolus tracked 0.5-0.625 mm Retrospective gating - full chest FOV
Plane Acquisition FOV Thickness/Increment Kernel IR Strength Notes
Axial Calcium score Chest 3 mm/3 mm Standard 3 For Agatston score calculation
Axial Gated CTA Full chest 0.6 mm/0.6 mm Cardiac 3 Thin slice for grafts and native vessels
Sagittal Gated CTA Chest 2 mm/2 mm Standard 3 Extracardiac assessment
3D VR Gated CTA Heart/grafts 0.5 mm source Cardiac 3 MPRs by 3D lab