CTA is being increasingly used as the preferred initial imaging exam for ALI due to several attributes. Due to systemic delivery of contrast, CTA can effectively delineate entire limb arterial anatomy simultaneously. This is useful for identifying the extent of thrombosis as well as proximal and distal vessel targets for intervention. Sluggish flow particularly within the tibial vessels and distally can limit the delivery of contrast and therefore reduce the amount of information provided by the exam. Additional information readily available via CTA includes vessel calcification, vessel diameter, collateralization, and presence of previous stents or bypass grafts. CTA is, however, a static study providing very little information about flow dynamics. Disadvantages include the need for radiation and potentially nephrotoxic contrast.

Contrast angiography is considered by many to be the gold-standard imaging modality for ALI. Angiography has the indisputable advantage of being both diagnostic and potentially therapeutic. It also provides information regarding flow characteristics. Angiography, however, only provides information available through opacification of the vessel lumen and therefore does not provide any extralumenal assessment. Collateral pathways can be quite variable in ALI and the ability to opacify vessels distal to the affected region requires catheter selection of the appropriate supplying collateral pathway as well as adequate timing to allow for contrast to be delivered. Angiography, like CTA, also uses radiation and potentially nephrotoxic contrast; however, contrast volumes are often less than CTA. Additional risks are associated with arterial cannulation and intralumenal manipulation but are relatively minimal.

Duplex ultrasound (US), although not frequently used for ALI, can provide some valuable information expeditiously, especially if readily performed by the provider. In cases of strongly suspected arterial embolism, the location of embolus can be quickly confirmed via US. Also potential access points for arterial cannulation can be quickly assessed for feasibility. Lastly, availability of venous conduit for arterial reconstruction can be ascertained.

Management of Rutherford Class I ischemia with anticoagulation alone is appropriate, allowing time for more thorough evaluation and possibly elective revascularization.

For Class IIa and IIb ischemia, anticoagulation alone is not sufficient and prompt revascularization is warranted to prevent further ischemic damage.

Class III ischemia implies irreversible damage requiring some level of amputation; however, treatment may be incorporated to lower the level of amputation.