What imaging tests are recommended to diagnose peripheral arterial disease (PAD) in patients presenting with leg claudication?

Diagnostic Imaging for Leg Claudication

For patients with suspected peripheral arterial disease (PAD) presenting with leg claudication, the initial diagnostic test should be the ankle-brachial index (ABI), followed by appropriate physiological testing and anatomic imaging only when revascularization is being considered. 1

Initial Diagnostic Approach

Step 1: Ankle-Brachial Index (ABI)

• ABI is the recommended first-line diagnostic test for PAD in patients with claudication symptoms 1
• Performed by measuring systolic blood pressures at the arms (brachial arteries) and ankles (dorsalis pedis and posterior tibial arteries) in supine position using a Doppler device
• ABI results should be reported as:
  • Abnormal: ABI ≤0.90
  • Borderline: ABI 0.91–0.99
  • Normal: ABI 1.00–1.40
  • Noncompressible: ABI >1.40

Step 2: Additional Physiological Testing

• For patients with normal or borderline ABI (>0.90 and ≤1.40) but exertional leg symptoms:

  • Exercise treadmill ABI testing is indicated to evaluate for PAD 1

• For patients with noncompressible arteries (ABI >1.40):

  • Toe-brachial index (TBI) should be measured to diagnose PAD 1

• For patients with abnormal ABI (≤0.90):

  • Exercise treadmill ABI testing can help objectively assess functional status 1

Advanced Imaging (Only When Revascularization is Considered)

For patients with confirmed PAD who have lifestyle-limiting claudication and are being considered for revascularization, anatomic imaging is appropriate:

1. Non-invasive options: 1

   • Duplex ultrasound
   • CT angiography (CTA)
   • Magnetic resonance angiography (MRA)

2. Invasive angiography: 1

   • Reasonable for patients with lifestyle-limiting claudication who have inadequate response to guideline-directed medical therapy
   • Should not be performed for asymptomatic PAD

Clinical Pearls and Pitfalls

• Important caveat: ABI has high sensitivity (85.3%) and specificity (85.7%) for diagnosing PAD in patients with atypical claudication 2
• Common pitfall: Performing invasive or non-invasive angiography for asymptomatic PAD is potentially harmful and should be avoided 1
• Key consideration: Despite being grade 1, level A evidence, studies show ABI is underutilized in clinical practice, with only 22.5% of patients having ABI measured both before and after peripheral vascular interventions 3
• Diagnostic challenge: The correlation between ABI values and walking capacity/quality of life is relatively weak (r = 0.278-0.343), suggesting that clinical decisions should not be based exclusively on ABI values 4

Special Populations

• For diabetic patients with PAD: 1
  • The same diagnostic workup should be implemented as in patients without diabetes
  • Annual screening for PAD with clinical assessment and/or ABI measurement is indicated
  • For below-the-knee lesions in chronic limb-threatening ischemia, angiography including foot run-off should be considered before revascularization

By following this evidence-based diagnostic approach, clinicians can accurately diagnose PAD in patients with leg claudication and appropriately select patients who may benefit from revascularization procedures.