Role of lower extremity run-off CT angiography in the evaluation of acute vascular disease

In the acute care setting, radiologists are frequently asked to assist in the evaluation of patients presenting with signs and symptoms of lower extremity peripheral vascular disease. Non-traumatic peripheral vascular emergencies are most commonly the result of thrombosis, either in a native vessel or within a bypass graft or stent. Arterial emboli, peripheral aneurysm with embolus or thrombosis, and direct arterial trauma are additional, less common causes. Traumatic peripheral vascular emergencies include vessel occlusion, transection, pseudoaneurysms, active extravasation, and arteriovenous fistulas. The high morbidity and mortality associated with acute limb ischemia makes rapid diagnosis and early initiation of therapy critical in the management of such patients. Computed tomographic angiography (CTA) offers the vascular specialist a rapid, widely available, and accurate means to diagnose and grade the extent of vascular disease in the acute care setting. In this pictorial essay, the key elements of lower extremity run-off CTA are reviewed, including relevant anatomy, imaging approach, and spectrum of imaging findings.