From the Guidelines
Ultrasound is used in ankle-brachial index (ABI) measurements to enhance the accuracy and reliability of this vascular assessment, particularly in patients with calcified vessels or those with conditions like diabetes where vessel compressibility may be altered. The traditional ABI measurement uses a blood pressure cuff and Doppler probe to compare blood pressure in the arms and ankles, but ultrasound provides several advantages, including direct visualization of blood vessels and detection of arterial stenosis, occlusions, and other vascular abnormalities that might affect ABI readings 1. According to the 2024 ACC/AHA/AACVPR/APMA/ABC/SCAI/SVM/SVN/SVS/SIR/VESS guideline, the resting ABI is recommended to establish the diagnosis of peripheral arterial disease (PAD) in patients with history or physical examination findings suggestive of PAD 1.
Some of the key benefits of using ultrasound in ABI measurements include:
- Direct visualization of blood vessels, allowing for more precise location of arteries
- Detection of arterial stenosis, occlusions, and other vascular abnormalities
- Real-time blood flow information, enabling more accurate measurements in patients with irregular pulses or conditions like diabetes
- Improved diagnostic accuracy for PAD, leading to more appropriate treatment decisions
The use of ultrasound in ABI measurements is supported by recent studies, including the 2024 ACC/AHA/AACVPR/APMA/ABC/SCAI/SVM/SVN/SVS/SIR/VESS guideline, which recommends the use of resting ABI to establish the diagnosis of PAD 1. Additionally, a study published in the Journal of the American College of Radiology in 2018 highlights the benefits of using ultrasound in vascular imaging, including its ability to detect patent tibial arteries and quantify the firmness of occlusions 1.
Overall, the use of ultrasound in ABI measurements is a valuable tool for enhancing the accuracy and reliability of vascular assessments, particularly in patients with complex vascular conditions. The combination of ultrasound with traditional ABI assessment improves diagnostic accuracy for peripheral arterial disease, leading to more appropriate treatment decisions.
From the Research
Use of Ultrasound on Ankle-Brachial Index (ABI)
- Ultrasound is used in conjunction with ABI to detect peripheral arterial disease (PAD) due to its high sensitivity and specificity 2.
- Continuous-wave Doppler ultrasound (CWD) has been shown to be a complementary test to ABI in detecting stenotic PAD, especially in cases where ABI has decreased sensitivity 2.
- The use of Doppler ultrasound waveforms has also been explored in predicting abnormal ABI using artificial intelligence, with high accuracy and sensitivity 3.
Diagnostic Accuracy of ABI and Ultrasound
- Studies have shown that ABI has low sensitivity (7%-34%) but high specificity (96%-100%) in screening populations 4.
- The combination of ABI and Doppler ultrasound has been found to be more accurate in diagnosing PAD, especially in diabetic patients 5.
- ABI measurement has been found to be a sensitive and specific method for diagnosing PAD in diabetic patients, with a prevalence of 56.25% in a selected population 5.
Prognostic Significance of ABI and Ultrasound
- An abnormal ABI has been found to be an independent prognostic marker of cardiovascular events among patients with coronary artery disease (CAD) 6.
- Patients with subclinical PAD (abnormal ABI without clinical symptoms) have been found to have poor outcomes, including increased risk of major adverse cardiovascular events (MACE) and 1-year mortality 6.
- Routine ABI screening, potentially combined with ultrasound, may carry important prognostic significance in patients with acute coronary syndrome (ACS) 6.