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CTA Lower Extremity Free Flap

Last Updated: 2026-01-01 Author:

  • 1. Clinical Summary

    Series Phase Coverage
    CTA Arterial Arterial (bolus tracked) Mid-thigh to Toes
    Delay Delayed (60s) Mid-thigh to Toes
    • Pre-operative planning for free flap harvest (fibula ALT anterolateral thigh)

  • 2. Patient Prep

    • Position: Supine with legs extended
    • NPO Status: NPO 2-4 hours

  • 3. IV Contrast & Injection

    Parameter Value
    Agent Isovue 370
    Volume 1.5 mL/kg
    Flow Rate 4-5 mL/s
    Duration 25s
    Timing Method Bolus Tracking
    ROI Placement Femoral 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

    • Scan from iliac crest to ankle. Focus on perforators in region of interest. Arterial phase critical for mapping
    • Additional Recons: Curved MPR of main vessels. Measure perforator locations from bony landmarks
    • 18-20G IV

    Safety First

    • Renal Function: Verify eGFR > 30
    • Allergy: Check allergy history
    • Map perforator vessels. Measure vessel caliber and length. Identify dominant pedicle. Note anatomic variants
    • Legs straight and not rotated. Mark skin over region of interest if possible
Series Name Start Location End Location Delay Slice Thickness Notes
Scout/Topogram Mid-Thigh Toes N/A N/A AP both legs for comparison
CTA Arterial Mid-Thigh Toes Bolus tracked 0.625 mm Bilateral for comparison and variants
CTA Delayed Mid-Thigh Toes 60s 0.625 mm Bilateral for comparison and variants
Plane Acquisition FOV Thickness/Increment Kernel IR Strength Notes
Axial Arterial Thighs/Legs 1 mm/1 mm Vascular 3 Thin slice for perforator identification
Coronal Arterial Full legs 1.5 mm/1.5 mm Vascular 3 MIP to show perforator course
Sagittal Arterial Full legs 2 mm/2 mm Vascular 3 Lateral perforator views