What imaging modalities are used to diagnose peripheral artery disease?

Imaging for Peripheral Artery Disease Diagnosis

Start with ankle-brachial index (ABI) measurement—no imaging is needed to diagnose PAD. 1, 2

Initial Diagnostic Testing (No Imaging Required)

• Measure resting ABI as the first-line test to establish the diagnosis of PAD 1
• An ABI ≤0.90 confirms PAD and no imaging is necessary to start guideline-directed medical therapy 1, 2
• Report ABI results as: abnormal (≤0.90), borderline (0.91-0.99), normal (1.00-1.40), or noncompressible (>1.40) 1

When ABI is Noncompressible (>1.40)

• Measure toe-brachial index (TBI) as the alternative diagnostic test 1
• Other alternatives include Doppler waveform analysis or pulse volume recording 1
• These tests bypass the problem of calcified, incompressible vessels 1

When to Perform Exercise Testing (Still No Imaging)

• Order exercise treadmill ABI testing if the patient has exertional leg symptoms but normal or borderline resting ABI (>0.90 and ≤1.40) 1
• This unmasks PAD that is only apparent with exercise 1

When Imaging IS Indicated

Imaging is only needed when revascularization is being considered—not for routine diagnosis. 1, 2

For Symptomatic PAD Considering Revascularization:

First-line imaging options (all Class I recommendations): 1

• Duplex ultrasound is the first-line imaging method to confirm lesion location 1
• CT angiography (CTA) provides excellent anatomic detail with 3D reconstruction 1
• MR angiography (MRA) offers similar accuracy without radiation 1

Choosing Between Imaging Modalities:

Duplex ultrasound advantages: 1, 2

• No radiation or contrast exposure
• Excellent for routine follow-up after revascularization 1
• Sensitivity 85-90% and specificity >95% for detecting stenosis >50% 1

Duplex ultrasound limitations: 1

• Operator-dependent and requires good training 1
• Lower spatial resolution than CTA/MRA, especially with arterial calcification 1
• Does not provide a complete roadmap of entire vasculature 1

CTA advantages: 1

• Sensitivity 96-98% and specificity 94-98% for aorto-iliac and femoro-popliteal stenoses 1
• Visualizes calcifications, stents, bypasses, and aneurysms 1
• Provides 3D reconstruction for treatment planning 1

CTA limitations: 1, 3

• Requires iodinated contrast (risk of contrast-induced nephropathy) 1, 3
• Ionizing radiation exposure 1, 3
• Severe calcifications can impede stenosis assessment in distal arteries 1

MRA advantages: 1

• No ionizing radiation 1
• Sensitivity and specificity 95% for segmental stenosis 1
• Superior for tibial arteries in expert centers 1

MRA limitations: 1

• Gadolinium contrast contraindicated in severe renal dysfunction (risk of nephrogenic systemic sclerosis) 1, 3
• Tends to overestimate stenosis severity 1
• Cannot visualize arterial calcifications 1
• Poor visualization of steel stents 1

When to Proceed Directly to Catheter Angiography:

For critical limb-threatening ischemia (CLTI): 1, 3

• Invasive angiography is useful when revascularization is considered (Class I) 1
• Timely diagnosis and treatment are essential to preserve tissue viability, so proceeding directly to angiography with intervention avoids delay 1, 3

For lifestyle-limiting claudication: 1

• Invasive angiography is reasonable (Class IIa) if the patient has failed guideline-directed medical therapy and revascularization is being considered 1
• This approach combines diagnostic assessment with potential immediate intervention 1

Special Populations

Diabetic Foot Ulcers:

• Measure both ankle systolic pressure and ABI, plus evaluate pedal Doppler waveforms 1
• Consider urgent vascular imaging if toe pressure <30 mmHg or transcutaneous oxygen pressure (TcPO2) <25 mmHg 1
• Color Doppler ultrasound, CTA, MRA, or digital subtraction angiography can each be used when revascularization is necessary 1
• Visualize the entire lower extremity circulation with detailed below-the-knee and pedal artery assessment 1

Common Pitfalls to Avoid

• Do not order imaging for asymptomatic PAD—invasive and noninvasive angiography should not be performed for anatomic assessment in asymptomatic patients 1
• Do not skip the ABI—always confirm PAD diagnosis with ABI before proceeding to anatomic imaging 2
• Do not use CTA in severe renal dysfunction without considering the nephropathy risk and ensuring adequate hydration 1, 3
• Do not use gadolinium-based MRA in patients with advanced renal dysfunction due to nephrogenic systemic sclerosis risk 1, 3
• Remember that imaging data must be analyzed in conjunction with symptoms and hemodynamic tests before making treatment decisions 1