Lower Extremity VasculatureLive data

CTA Lower-Limb Runoff

CT angiography of the lower-limb runoff evaluates the arterial tree from the infrarenal aorta and iliac arteries through the femoropopliteal segment to the tibial and pedal vessels. It is a primary non-invasive tool for peripheral arterial disease, mapping stenoses, occlusions and runoff for revascularisation planning.

Indications

Intermittent claudication with an abnormal ankle-brachial index
Critical (chronic) limb-threatening ischaemia with rest pain or tissue loss
Pre-procedural planning for endovascular or surgical revascularisation
Acute limb ischaemia and suspected arterial embolism or thrombosis
Surveillance of bypass grafts, stents and known aneurysms

Contraindications & Cautions

Severe iodinated contrast allergy without adequate premedication
Significant renal impairment (balance diagnostic need against contrast nephrotoxicity)
Extensive vascular calcification limiting luminal assessment (consider alternative imaging)
Haemodynamic instability precluding transport and acquisition

Patient Preparation

Screen for iodinated contrast allergy and assess renal function
Secure reliable intravenous access, ideally antecubital, for power injection
Position the patient supine with the feet secured and immobilised
Warm the room and consider vasodilatation strategies to optimise distal opacification

Technique & Parameters

Bolus tracking with region of interest in the suprarenal/infrarenal aorta, or a test bolus, to time the acquisition
Coverage from the renal arteries or aortic bifurcation to the pedal arteries
Contrast 100-150 mL at 4-5 mL/s with a saline chaser; biphasic injection to prolong distal enhancement
Slow table speed or delayed acquisition to accommodate slow distal flow in severe disease
Thin collimation (≤1 mm) with MIP, curved planar and volume-rendered reformats for reporting

Systematic Review

Assess the infrarenal aorta and iliac arteries for stenosis, occlusion and aneurysm
Evaluate the common femoral, superficial femoral and profunda femoris arteries
Trace the popliteal artery and the tibioperoneal trunk
Count and grade the three-vessel tibial runoff (anterior tibial, posterior tibial, peroneal) to the pedal arch
Review collateral pathways, grafts, stents and any signs of dissection or embolism

Key Findings & Significance

Focal or long-segment stenoses and occlusions with quantifiable luminal narrowing
Superficial femoral artery occlusion at the adductor (Hunter) canal with reconstitution via collaterals
Distribution of atherosclerotic and medial (Monckeberg) calcification affecting luminal evaluation
Number of patent runoff vessels and integrity of the pedal arch (key for bypass planning)
Aneurysm (e.g. popliteal), in-stent restenosis, graft stenosis or thrombosis

Differential Considerations

Atherosclerotic peripheral arterial disease versus embolic occlusion
Popliteal artery entrapment syndrome versus cystic adventitial disease in younger patients
Thromboangiitis obliterans (Buerger disease) versus diffuse distal atherosclerosis
Vasculitis versus atherosclerotic stenosis
True luminal stenosis versus artefactual narrowing from dense calcification or blooming

Pearls & Pitfalls

Mistimed acquisition can outrun the contrast bolus distally, mimicking occlusion; verify enhancement to the feet
Heavy tibial calcification degrades luminal assessment; dual-energy or duplex ultrasound can complement CTA
Document the number of patent runoff vessels and pedal arch, as these determine bypass target and outcome
Correlate with ankle-brachial index and clinical stage (e.g. Rutherford classification) in the report

Structured Report

Report segment by segment from aorta to pedal arteries with location and severity of disease
Grade stenoses (e.g. <50%, 50-70%, 70-99%, occlusion) and give occlusion lengths
State the number and quality of tibial runoff vessels and pedal arch patency
Describe grafts, stents, aneurysms and any complications
Provide an integrated conclusion supporting endovascular versus surgical planning

References

ACR-NASCI-SPR Practice Parameter for the Performance and Interpretation of Body CT Angiography
Radiographics: Fleischmann D et al. CT Angiography of Peripheral Arterial Disease
ACR Appropriateness Criteria: Lower Extremity Arterial Claudication - Non-Invasive Vascular Imaging
ACC/AHA Guideline on the Management of Patients with Lower Extremity Peripheral Artery Disease

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

CTA Lower-Limb Runoff

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References