Multi-slice CT evaluation of acute mesenteric ischemia induced by ligation of superior mesenteric vein in a porcine model

Objective: To investigate MSCT for detecting the early sign and dynamic evolution of acute mesenteric ischemia (AMI) induced by ligation of superior mesenteric vein (SMV) in experimental porcine model. Methods: Twelve pigs were assigned randomly to three experimental groups and one control group with 3 pigs in each group. After laparotomy, SMV was separated and ligated in 9 pigs, and separated without ligation in 3 control pigs. Pre-and postcontrast MSCT with arterial, venous and delay phase scans, and CT angiography (CTA) reconstructions of mesenteric vessels were carried out at preoperation, 6,12 and 18 h after ligation. The changes of mesenteric vessels, bowel, abdominal cavity pre-and post-operation, and dynamic evolution were evaluated. The results were compared with those of pathology. Results: AMI changes were identified pathologically in all 9 experimental pigs. MSCT angiography clearly delineated main trunk of SMV, peripheral major and minor tributaries up to brushy vasa recta. It correctly identified the location and shape of ligations. The early ischemic findings appeared as follows: the spasm of superior mesenteric artery (SMA) and its major branches which displayed poor filling and delayed and prolonged visualization, poor and delayed opacification of SMV and its tributaries, bowel wall thickness, mesenteric stranding, ascite and pronounced bowel enhancement. With time lapse, thinning bowel wall, dilated bowel with fluid, aggravating edema of mesentery and ascite and poor enhanced bowel were identified. Conclusion: CTA can reliably define normal and occluded mesenteric vessels, detect early changes mesenteric ischemia and evolution, and diagnosis venous occlusive AMI. (authors)