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CTA Popliteal Entrapment

Last Updated: 2026-01-01 Author:

  • 1. Clinical Summary

    Series Phase Coverage
    CTA Neutral Position Arterial (bolus tracked from 1st injection) 4cm above the knees to the toes
    CTA Delayed Neutral Position Delayed Arterial (40 sec delay from 1st injection) 4cm above the knees to the toes
    CTA Plantarflexion Arterial (bolus tracked from 2nd injection) 4cm above the knees to the toes
    • Popliteal entrapment syndrome
    • Exercise-induced leg pain
    • Young patient with claudication

  • 2. Patient Prep

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

  • 3. IV Contrast & Injection

    Parameter Value
    Agent Isovue 370
    Volume Dual injection: 1.2 mL/kg + 1.2 mL/kg
    Flow Rate 4 mL/s
    Duration 18-20s + 18-20s
    Timing Method Bolus Tracking
    ROI Placement Popliteal 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

    • TWO acquisitions required: 1) Neutral position 2) Active plantarflexion. Both legs scanned for comparison. Coach patient on plantarflexion technique
    • Additional Recons: Side-by-side comparison of neutral vs plantarflexion. 3D VR showing muscle-vessel relationship
    • 18-20G IV antecubital

    Safety First

    • Renal Function: Verify eGFR > 30
    • Allergy: Check allergy history. Explain plantarflexion maneuver to patient
    • Compare neutral vs plantarflexion images. Look for popliteal artery compression deviation or occlusion with plantarflexion. Assess muscle anatomy
    • Coach patient on maintaining plantarflexion during second acquisition. Use foot straps if needed
Series Name Start Location End Location Delay Slice Thickness Notes
Scout/Topogram Distal femur Ankle N/A N/A AP both legs
CTA Neutral Position Distal femur Ankle Bolus tracked from 1st injection 0.625 mm Both legs neutral resting position
CTA Delayed Neutral Position Distal femur Ankle 40 sec delay from 1st injection 0.625 mm Both legs neutral resting position
CTA Plantarflexion Distal femur Ankle Bolus tracked from 2nd injection 0.625 mm Patient actively plantarflexes both feet - point toes
Plane Acquisition FOV Thickness/Increment Kernel IR Strength Notes
Axial Neutral Both legs 1.5 mm/1.5 mm Vascular 3 Baseline popliteal artery anatomy
Axial Plantarflexion Both legs 1.5 mm/1.5 mm Vascular 3 Assess for compression with maneuver
Coronal Both phases Both legs 2 mm/2 mm Vascular 3 MIP comparison neutral vs flexion
Sagittal Both phases Both legs 2 mm/2 mm Vascular 3 Lateral view popliteal fossa