DEVISING DUPLEX ULTRASOUND STAGING FOR LOWER EXTREMITY ARTERIAL DISEASE CORRESPONDING TO FONTAINE CLINICAL STAGING

Background: Lower extremity arterial disease (LEAD) is a progressive atherosclerotic condition that significantly affects mobility, quality of life, and cardiovascular risk. Early and accurate staging is crucial for timely intervention and optimal disease management. While the Fontaine classification is widely used clinically, there is a need for a standardized, non-invasive imaging-based staging method that aligns with clinical assessment and enhances diagnostic precision. Objective: To develop and validate a duplex ultrasound (DUS)-based staging system for LEAD that corresponds to Fontaine clinical stages, enabling precise hemodynamic evaluation and disease monitoring. Methods: A cross-sectional observational study was conducted from September 2022 to September 2023, involving 135 adult patients with suspected or confirmed LEAD. All participants underwent detailed clinical assessment and DUS evaluation of bilateral lower limb arteries, including the common femoral, superficial femoral, popliteal, and tibial arteries. Sonographic parameters recorded included peak systolic velocity (PSV), waveform morphology, and presence of flow disturbances. These findings were correlated with Fontaine stages I to IV. Inter-observer reliability was assessed using Cohen’s kappa coefficient. Results: Stage I showed triphasic waveforms and normal PSV; Stage IIa exhibited mild PSV elevation (<100%) without turbulence; Stage IIb demonstrated PSV increases of 100–200% with disturbed flow and biphasic/monophasic waveforms; Stage III revealed severe stenosis (PSV >200%) and monophasic waveforms; and Stage IV presented with occlusion and absent flow. The DUS-based system showed a sensitivity of 92%, specificity of 96%, positive predictive value of 91%, and negative predictive value of 96%. Inter-observer agreement was excellent (κ = 0.87). Conclusion: The proposed DUS staging framework provides a reliable, reproducible, and non-invasive alternative to clinical classification, supporting early diagnosis, treatment planning, and ongoing management of LEAD in routine practice.