protocol: CT angiography for GI bleed

No oral contrast

Section thickness 1 mm
Reconstruction interval 0.8 mm

Unenhanced low dose CT (to show pre-existing intraluminal hyperattenuation)

100–125 mL I.V contrast 4 mL/sec, followed by 50 mL of saline solution at 4 mL/sec

Arterial phase - triggering at proximal abdominal aorta (150 HU)

Portal venous phase at 70 seconds

Reference:
Marti M et al. Acute Lower Intestinal Bleeding: Feasibility and Diagnostic Performance of CT Angiography, January 2012 Radiology, 262, 109-116.