Figure 8b. Total occlusion of the infrarenal abdominal aorta. (a) Sagittal reformatted image of the abdominal aorta depicts calcification and mural thrombosis (arrows). (b) Contrast-enhanced axial CT scan shows collateral circulation, epigastric arteries (large white arrows), circumflex arteries (small white arrows), an enlarged inferior mesenteric artery (arrowhead), and enlarged lumbar arteries (black arrows). (c) Sagittal maximum-intensity projection image shows enlarged epigastric arteries in the abdominal wall (arrows) and retrograde flow in the inferior mesenteric artery (arrowhead). (d) Coronal volume-rendered image shows a collateral pathway proceeding from the subcostal arteries through the circumflex arteries to the external iliac artery (arrows). Note the enlarged inferior mesenteric artery (arrowhead).