Review of pelvic collateral pathways in aorto-iliac occlusive disease: demonstration by CT angiography

The pelvic collateral system is a robust network of communicating vessels that provide the functional reserve to withstand chronic aorto-iliac occlusive disease. For establishment of collateral circulation, the afferent vessel must originate proximal to the occlusion and anastomose with vessel/s distal to the occlusion. These collateral pathways can be classified as viscero-systemic, systemic-systemic, and visceral-visceral. CT angiography (CTA) is often the initial modality for evaluating patients with atherosclerotic vascular disease, because it is non-invasive and has been shown to be comparable to conventional angiography. Most collateral pathways are well demonstrated on CTA, which therefore is a useful tool for preoperative planning and regional interventional procedures.