Figure 6a. Aortoduodenal fistula in a 70-year-old man who presented with anemia caused by intestinal bleeding of unknown origin, 10 years after aortoiliac graft implantation. (a, b) Contrast-enhanced axial source image (a) and coronal MPR image (b) show extravasation of contrast material (arrowheads) into the horizontal or inferior duodenum. (c, d) Coronal MIP image (c) and coronal VR image (d) from venous phase imaging show the advantage of two-phase CT: On an arterial phase image, only a small amount of contrast material is evident in the duodenum, whereas the venous phase images show active bleeding (arrow) into the duodenum. (Blood is depicted in yellow.) (e, f) Axial VR image (e) and sagittal MPR image (f) show the exact location of the fistula (arrow).