Which diagnostic test is primarily used to diagnose peripheral arterial disease (PAD)?

Which diagnostic test is primarily used to diagnose peripheral arterial disease (PAD)?

• A. Ankle-brachial index (ABI)
• B. Doppler ultrasound
• C. Angiography
• D. Magnetic resonance angiography

Answer: (A)

Assessing leg perfusion starts with a simple, noninvasive measure: compare the blood pressure in the ankles with the blood pressure in the arms. This ankle-brachial index is calculated as the ankle systolic pressure divided by the arm systolic pressure. A normal range is about 1.0 to 1.4. When the ratio drops to 0.90 or lower, it indicates peripheral arterial disease, with lower values reflecting more severe disease. This test is the best first step because it is quick, inexpensive, easy to perform in most settings, and highly effective at detecting reduced blood flow to the legs—even in people who don’t yet have classic symptoms. Be mindful that in people with calcified arteries (common in diabetes) the arteries may be less compressible, which can make the ABI unreliable; in those cases a toe-brachial index or additional imaging may be needed. Other tests like Doppler ultrasound help visualize blood flow and locate where narrowing occurs and are useful as follow-up or when the ABI is inconclusive. Angiography provides detailed images of the arteries and is typically reserved for planning treatment or when noninvasive tests don’t give a clear answer. Magnetic resonance angiography offers another noninvasive option for imaging but is usually used when more detail is needed or when other modalities aren’t suitable.

Assessing leg perfusion starts with a simple, noninvasive measure: compare the blood pressure in the ankles with the blood pressure in the arms. This ankle-brachial index is calculated as the ankle systolic pressure divided by the arm systolic pressure. A normal range is about 1.0 to 1.4. When the ratio drops to 0.90 or lower, it indicates peripheral arterial disease, with lower values reflecting more severe disease. This test is the best first step because it is quick, inexpensive, easy to perform in most settings, and highly effective at detecting reduced blood flow to the legs—even in people who don’t yet have classic symptoms.

Be mindful that in people with calcified arteries (common in diabetes) the arteries may be less compressible, which can make the ABI unreliable; in those cases a toe-brachial index or additional imaging may be needed. Other tests like Doppler ultrasound help visualize blood flow and locate where narrowing occurs and are useful as follow-up or when the ABI is inconclusive. Angiography provides detailed images of the arteries and is typically reserved for planning treatment or when noninvasive tests don’t give a clear answer. Magnetic resonance angiography offers another noninvasive option for imaging but is usually used when more detail is needed or when other modalities aren’t suitable.