Figure 1.

CT angiography in an 82-year-old male with bright red blood per rectum: on axial non-contrast CT (a), there is no hyperattenuating material in the bowel lumen. The axial arterial phase image (b) demonstrates active extravasation of contrast (arrows) into the second portion of the duodenum, which was found on endoscopy to arise from a duodenal ulcer. Ulcer disease is the most common cause of upper gastrointestinal bleeding.