Multidetector computed tomographic angiography (MDCTA) is the new gold standard for diagnostic evaluation of the abdominal and/or mesenteric arteries. It is not invasive and provides a 2D and 3D global cartography of all abdominal arteries and that with only a limited amount of contrast media. MDCTA allows the optimal diagnosis of single or multiple arterial stenosis and easily analyses sometimes very complex collateral pathways. It constitutes a major advance to plan the arterial visceral safety of major commonly performed abdominal surgical procedures such as aorto-iliac surgery, endovascular aneurysm repair (EVAR), but also complex pancreatic and gastrointestinal or colonic surgery. It also allows to plan the most optimal strategy for revascularization of the mesenteric system through percutaneous angioplasty, stent placement or surgical bypass. This extensive pictorial review illustrates a large variety of situations which may be found during clinical practise. Single compression or stenosis of each digestive artery, combined and/or complex associations of stenosis and/or compressions of several arteries, secondary complications like aneurysms and classical but also sometimes unusual patterns of collateralization are richly illustrated. Specific syndromes comprising the median arcuate ligament syndrome (MALS) and the Leriche\'s syndrome are also discussed.

OBJECTIVE: Our aim to assess clinical significance of the relation between inferior mesenteric vein ligation and collateral blood supply (meandering mesenteric artery) to the splenic flexure with elaboration more in anatomical landmarks and technical tips.
METHODS: We review the literature regarding the significance of the collateral vessels around inferior mesenteric vein (IMV) root and provide our prospective operative findings, anatomical landmarks and technical tips. We analyzed the incidence and pattern of anatomic variation of collateral vessels around the IMV.
RESULTS: A total of 30 consecutive patients have been prospectively observed in a period between June 25-2012 and September 7-2012. Nineteen males and eleven females with mean age of 63 years. Major colorectal procedures were included. There were three anatomical types proposed, based on the relation between IMV and the collateral vessel. Type A and B in which either the collateral vessel crosses or runs close to the IMV with incidence of 43.3% and 13.3%, respectively, whereas type C is present in 43.3%. There was no definitive relation between the artery and vein. No intra or postoperative ischemic events were reported.
CONCLUSIONS: During IMV ligation, inadvertent ligation of Arc of Riolan or meandering mesenteric artery around the IMV root \"in type A&B\" might result in compromised blood supply to the left colon, congestion, ischemia and different level of colitis or anastomotic dehiscence. Therefore, careful dissection and skeletonization at the IMV root \"before ligation if necessary\" is mandatory to preserve the collateral vessel for the watershed area and to avoid further injury.