Aortoiliofemoral Lower Extremity CT Angiography.

CT angiography (CTA) of the aortoiliofemoral (AIF) arteries in the abdomen, pelvis, and lower extremities has become an invaluable tool in assessment of patients with peripheral arterial disease (PAD) and lower extremity trauma. AIF CTA provides rapid and comprehensive assessment of arterial inflow and outflow, guiding management of patients with chronic claudication and those with more acute manifestations, including atherothrombotic occlusion, embolic disease, or thrombosis of prior interventions such as bypass graft or stent placement. Careful attention to technique is critical in performing diagnostic AIF CTA, as pitfalls related to imaging too early or too late relative to the arrival of contrast material in the legs can lead to misdiagnosis or diagnostic uncertainty. The protocol can be tailored to the clinical scenario; for instance, the chest can be additionally imaged when aortic dissection affecting lower extremity perfusion, trauma, and embolic disease are clinical considerations. Additionally, when one is imaging patients with prior endovascular aortic repair, an additional delayed acquisition to assess for endoleak can be performed. Newer techniques such as dual-energy and photon-counting CT can improve endovascular enhancement, facilitate material decompensation, and produce virtual noniodine images. The authors detail normal vascular anatomy and key collateral pathways; AIF CTA protocols; and imaging of PAD, vascular trauma, and infectious or inflammatory disorders affecting the lower extremities. This knowledge, combined with a comprehensive approach to interpreting AIF CTA studies, will prepare the radiologist to offer optimal diagnostic value to guide clinical care. ©RSNA, 2025 Supplemental material is available for this article.