Peripheral Arterial Duplex Assessment, Protocols, and Interpretation

Peripheral arterial disease (PAD) affects 3% to 5% of the adult population over the age of 40. PAD is associated with increased mortality, occurring concomitantly with coronary artery disease and cerebrovascular accidents. PAD might present with claudication, rest pain, and or gangrene.  Noninvasive methods are the preferred diagnostic and monitoring modalities for PAD. Patients with a history and physical examination compatible with PAD are first evaluated with Duplex ultrasonography (DUS), which does not require contrast exposure and produces portable and reproducible images. However, in patients with obesity, the aortoiliac bifurcation may be obscured by bowel gas, so results must be interpreted cautiously. Arterial DUS provides two-dimensional structural images and Doppler ultrasonic signals over time. These signals can be analyzed with spectrum analysis and color flow velocity mapping for better documentation. The results of DUS are usually interpreted in conjunction with limb-pressure measurements to optimally categorize arterial hemodynamics and functional impairment. The accurate and precise interpretation of velocity spectra measured by DUS is essential to successfully applying the Duplex technique. The diagnosis of PAD relies on noninvasive arterial tests providing physiological and morphological information. Physiological tests include segmental pressures, ankle- and toe-brachial indices, pulse volume recordings, exercise tests, segmental volume plethysmography, transcutaneous oxygen assessments, and photoplethysmography. Morphological tests, including computed tomography (CT), magnetic resonance imaging (MRI), and catheter-based angiography, are ideal for evaluating preprocedural anatomic configurations in individuals with already established vascular disease. Peripheral arterial DUS provides a unique spectrum of details, including the anatomical location of the lesion, flow velocity, and volume.  DUS combines conventional B-mode imaging with pulsed Doppler flow detection techniques for spectral analysis. DUS accurately determines the location and degree of arterial stenosis while differentiating stenosis from an occlusion. DUS provides comprehensive anatomic and hemodynamic data crucial to planning revascularization. DUS is also used to monitor patients after angioplasty, stent replacement, and bypass grafting.