What imaging modalities are recommended for patients presenting with leg cramps concerning for Peripheral Artery Disease (PAD)?

Diagnostic Imaging for Peripheral Arterial Disease in Patients with Leg Cramps

The ankle-brachial index (ABI) is the recommended first-line diagnostic test for patients presenting with leg cramps concerning for peripheral arterial disease (PAD), followed by additional physiological testing and anatomic imaging only when revascularization is being considered. 1, 2

Initial Diagnostic Approach

Step 1: Ankle-Brachial Index (ABI)

• ABI is the initial non-invasive test of choice for suspected PAD 1
• 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 1
• Perform ABI with segmental pressures and waveforms to establish diagnosis and localize disease 1

Step 2: Additional Physiological Testing

Based on initial ABI results:

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

  • Exercise treadmill ABI testing is indicated to evaluate for PAD 1, 2

• For noncompressible arteries (ABI >1.40):

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

• For abnormal ABI (≤0.90):

  • Exercise treadmill ABI testing can help assess functional status 1
  • TBI with waveforms, transcutaneous oxygen pressure (TcPO2), or skin perfusion pressure (SPP) can be useful to evaluate local perfusion in patients with nonhealing wounds 1

Anatomic Imaging

Anatomic imaging is only recommended for patients in whom revascularization is being considered and should not be performed for asymptomatic PAD 1, 2.

Options for Anatomic Assessment:

1. Duplex Ultrasound:

   • Useful to diagnose anatomic location and degree of stenosis 1
   • Can be used to select patients for endovascular intervention 1
   • Class I recommendation with Level of Evidence A 1

2. CT Angiography (CTA):

   • Useful for anatomic assessment when revascularization is considered 1
   • May be considered as a substitute for MRA in patients with contraindications to MRA 1

3. Magnetic Resonance Angiography (MRA):

   • Useful to diagnose anatomic location and degree of stenosis 1
   • Should be performed with gadolinium enhancement 1
   • Useful in selecting patients for endovascular intervention 1

4. Invasive Angiography:

   • Reasonable for patients with lifestyle-limiting claudication with inadequate response to guideline-directed medical therapy 1
   • Useful for patients with critical limb ischemia in whom revascularization is considered 1
   • Provides detailed information about arterial anatomy 1

Important Clinical Considerations

• ABI is 57% to 79% sensitive and 83% to 99% specific for arterial stenosis of at least 50% 3
• The sensitivity of ABI varies with the location of disease, being lowest (40%) in isolated crural disease 4
• Combining ABI with pulse-volume recordings can increase both sensitivity and specificity to 94% and 96%, respectively 4
• Performing invasive or non-invasive angiography for asymptomatic PAD is potentially harmful and should be avoided 1, 2

Diagnostic Algorithm

1. First-line: Perform resting ABI with segmental pressures and waveforms
2. If ABI >1.40: Measure toe-brachial index
3. If ABI normal/borderline but symptoms persist: Perform exercise treadmill ABI testing
4. If revascularization is being considered: Proceed to anatomic imaging with duplex ultrasound, CTA, or MRA
5. If critical limb ischemia or inadequate response to therapy: Consider invasive angiography

This approach ensures appropriate diagnosis while avoiding unnecessary testing, focusing on tests that will impact morbidity, mortality, and quality of life outcomes for patients with suspected PAD.