Imaging evaluation of lower extremity infrainguinal disease: role of the noninvasive vascular laboratory, computed tomography angiography, and magnetic resonance angiography.

Peripheral arterial disease (PAD) is a manifestation of systemic atherosclerosis that commonly affects the lower extremities. The diagnosis of PAD and the subsequent treatment decisions rely on clinical exam and non-invasive imaging. The imaging modalities that aid in both diagnosis and treatment are the non-invasive vascular laboratory, computed tomography angiography (CTA) and magnetic resonance angiography (MRA). Each modality has its own advantages and limitations. Non-invasive vascular laboratory testing can be used as a good screening tool for PAD and is often used in conjunction with an additional imaging modality if necessary. CTA and MRA have similar advantages when compared to the "gold standard" of digital subtraction angiography. CTA utilizes ionizing radiation, however is readily available and cheaper when compared to MRA. CTA is attractive due to its 3-D reconstruction and multiplanar ability, but CTA can be limited in the presence of calcification. MRA also is attractive for its 3-D multiplanar imaging. It is important for a clinician to be familiar with the principles and technical aspects of each modality as it relates to lower extremity infrainguinal disease.