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CTA SCAD/FMD Protocol

Last Updated: 2026-01-01 Author:

  • 1. Clinical Summary

    Series Phase Coverage
    Non-contrast Head Non-contrast Vertex to Foramen magnum
    CTA Neck Arterial (bolus tracked) Aortic arch to Vertex
    CTA CAP Contrast (35 sec after neck delay) Diaphragm to Pubic symphysis
    Post-contrast Head Contrast (After CAP delay) Vertex to Foramen magnum
    • Spontaneous coronary artery dissection screening
    • Fibromuscular dysplasia screening
    • Multi-vessel arterial assessment

  • 2. Patient Prep

    • Position: Supine with arms initially UP then DOWN
    • NPO Status: NPO 4 hours

  • 3. IV Contrast & Injection

    Parameter Value
    Agent Isovue 370
    Volume 150 mL total
    Flow Rate 4 mL/s
    Timing Method Multi-phase: NC Head + CTA Neck + CTA CAP arms up + Post-contrast Head arms down
    ROI Placement Multiple ROIs
    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 acquisitions: 1) NC Head arms down 2) CTA Neck bolus track 3) CTA CAP arms up 4) Post Head arms down. Patient repositions arms between scans
    • Additional Recons: Comprehensive MIP and 3D VR of all vascular beds. Measure vessel diameters. Document FMD findings
    • 20G IV minimum. Verify good flow for multiple phases

    Safety First

    • Renal Function: Verify eGFR > 30
    • Allergy: Check allergy history. Explain arm repositioning
    • Screen all vascular beds for FMD. Look for beading stenosis aneurysm dissection. Assess renal carotid vertebral intracranial arteries
    • Coach patient on arm repositioning. Multiple phases require good IV. Plan scan sequence carefully
Series Name Start Location End Location Delay Slice Thickness Notes
Non-contrast Head Vertex Foramen magnum N/A 5 mm Arms down - baseline
CTA Neck Aortic arch Vertex Bolus tracked 0.625 mm Arms down - carotid/vertebral
CTA CAP Diaphragm Pubic symphysis 35 sec after neck 0.625 mm Arms UP - renal and mesenteric
Post-contrast Head Vertex Foramen magnum After CAP 1.25 mm Arms DOWN - intracranial vessels
Plane Acquisition FOV Thickness/Increment Kernel IR Strength Notes
Axial All phases Respective FOV Phase-specific Vascular 3 Comprehensive arterial assessment
Coronal CTA phases Full body 2-3 mm/2-3 mm Vascular 3 MIP of all arterial territories
Sagittal CTA phases Full body 2-3 mm/2-3 mm Vascular 3 Lateral views all vessels
3D VR CTA phases Full body 1 mm source Vascular 3 3D reconstruction multi-territory