Estimation of toe brachial index based on forefoot Doppler waveforms

Area of Science:

• Vascular Medicine
• Diagnostic Imaging
• Biomedical Engineering

Background:

• The toe brachial index (TBI) is standard for assessing peripheral arterial disease (PAD) but has limitations.
• Doppler waveform characteristics (AccI, PSV, AT) of forefoot arteries are potential alternatives for TBI estimation.
• This study aimed to evaluate Doppler waveform characteristics as a reliable TBI alternative.

Purpose of the Study:

• To evaluate the association between Doppler waveform characteristics and standard TBI.
• To develop empirical equations for estimating TBI (eTBI) using Doppler data.
• To assess the accuracy, reproducibility, and clinical applicability of eTBI.

Main Methods:

• Prospective analysis of angle-corrected Doppler AccI, PSV, and AT in forefoot metatarsal arteries.
• Standard automated TBI measurements in 155 limbs of PAD patients.
• Development and validation of empirical equations for eTBI calculation.

Main Results:

• Doppler-derived AccI, PSV, and AT showed significant association with standard TBI (R²=0.88, 0.58, 0.62).
• eTBI equations demonstrated excellent agreement with standard TBI (average deviation -0.01 ± 0.10 for AccI).
• eTBI predicted TBI independently of patient factors; showed low variability and outperformed standard TBI post-revascularization.

Conclusions:

• eTBI derived from Doppler waveforms, especially AccI, is a reproducible, accurate, and clinically responsive alternative to standard TBI.
• Integration into routine diagnostics can enhance accessibility and precision in PAD care.
• Automated eTBI acquisition may improve screening efficiency in non-specialist settings.