Recommendations for Imaging for Anatomic Assessment
COR	LOE	Recommendations
I	B-NR	Duplex ultrasound, computed tomography angiography (CTA), or magnetic resonance angiography (MRA) of the lower extremities is useful to diagnose anatomic location and severity of stenosis for patients with symptomatic PAD in whom revascularization is considered.118,120–122
See Online Data Supplement 6.		For symptomatic patients in whom ABI/TBI confirms PAD and in whom revascularization is considered, additional imaging with duplex ultrasonography, CTA, or MRA is useful to develop an individualized treatment plan, including assistance in selection of vascular access sites, identification of significant lesions, and determination of the feasibility of and modality for invasive treatment. All 3 of these noninvasive imaging methods have good sensitivity and specificity as compared with invasive angiography.118,120–122 Renal function does not affect the safety of duplex ultrasonography, although duplex offers lower spatial resolution than CTA and MRA in the setting of arterial calcification. The tomographic data from CTA and MRA afford 3-dimensional reconstruction of the vessels examined. The iodinated contrast used in CTA confers risk of contrast-induced nephropathy and (rarely) severe allergic reaction123,124; CTA uses ionizing radiation. MRA does not use ionizing radiation; however, gadolinium contrast used frequently in MRA studies confers risk of nephrogenic systemic sclerosis for patients with advanced renal dysfunction and is therefore contraindicated in this population.125 The choice of the examination should be determined in an individualized approach to the anatomic assessment for each patient, including risk–benefit assessment of each study type. If these noninvasive tests are nondiagnostic, then invasive angiography may be required to delineate anatomy and plan revascularization.
I	C-EO	Invasive angiography is useful for patients with CLI in whom revascularization is considered.
N/A		By definition, CLI results from extensive PAD that limits tissue perfusion. Because timely diagnosis and treatment are essential to preserve tissue viability in CLI, it is often most effective and expeditious to pursue invasive angiography with endovascular revascularization directly, without delay and potential risk of additional noninvasive imaging.
IIa	C-EO	Invasive angiography is reasonable for patients with lifestyle-limiting claudication with an inadequate response to GDMT for whom revascularization is considered.
N/A		For patients with lifestyle-limiting claudication despite GDMT (including structured exercise therapy) for whom revascularization is being considered, proceeding directly to invasive angiography for anatomic assessment and to determine revascularization strategy is reasonable. In certain clinical settings, noninvasive imaging studies for anatomic assessment (ie, duplex ultrasound, CTA, or MRA) may not be available because of lack of local resources or expertise. In addition, there are clinical scenarios in which noninvasive studies for anatomic assessment may be perceived to confer greater risk to the patient than invasive angiography (eg, patient with advanced chronic kidney disease for whom contrast dose for invasive angiography would be lower than that required for CTA).
III: Harm	B-R	Invasive and noninvasive angiography (ie, CTA, MRA) should not be performed for the anatomic assessment of patients with asymptomatic PAD.123,124,126
See Online Data Supplements 6 and 7.		Angiography, either noninvasive or invasive, should not be performed for the anatomic assessment of patients with PAD without leg symptoms because delineation of anatomy will not change treatment for this population. This lack of benefit occurs in the setting of risk of contrast-induced nephropathy, patient discomfort, and allergic reactions.123,124,126 This recommendation does not address assessment of lower extremity aneurysmal disease or nonatherosclerotic causes of arterial disease, which is beyond the scope of this document.