الفهرس 
Anatomy of the Small IntestineOnly 14 pages are availabe for public view
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Abstract
Acute mesenteric ischemia is a fatal disorder, caused by decreased intestinal blood flow, vague and nonspecific clinical findings and limitations of diagnostic studies make the diagnosis a significant challenge for the physicians. Moreover, delays in diagnosis lead to increased mortality rate.
The blood supply of the intestine is derived predominantly from the celiac axis, the superior mesenteric artery and the inferior mesenteric artery.
The intestine has significant collateral circulation that allow for some protection from ischemia.
All diseases and conditions that affect arteries, including atherosclerosis, arteritis, aneurysms, arterial infection, dissection, arterial emboli, thrombosis, are reported to occur in the intestinal arteries.
Acute Mesenteric ischemia can be caused by arterial or venous occlusion or by a low-flow state.
In 60% to 70% of cases, the cause of acute mesenteric ischemia is occlusion of the SMA by either an embolism or thrombus.
In 20% to 30% of cases, the cause is nonocclusive a low-flow state caused by hypotension or certain medications.
In 5% to 10% of cases, acute mesenteric ischemia is caused by thrombosis of the mesenteric vein.
Multidetector CT (MDCT) is an ideal tool for the diagnosis of acute mesenteric ischemia. It is relatively non-invasive, requiring only a peripheral intravenous catheter for delivery of iodinated contrast material. It can be performed quickly and in a wide. range of patients, including those who are critically ill.
MDCT was performed in two phases: arterial phase determined automatically by the Bolus Pro Ultra technique with a threshold set at 140 HU and the portal phase which began 70 s after injection. Using an average of 100 ml (range 65–130) of nonionic contrast media, injected through an18-gauge antecubital intravenous line at a rate of 3.5 to 4.0 ml/s. Oral contrast agent was not given.
Because of rapid technological advances in both scanners and computer work stations, MDCT in many cases has replaced conventional catheter angiography for evaluation of the mesenteric vasculature and bowel.
CT angiography (CTA) yields volume data sets, that can be reformatted and viewed in any projection, visualizing even tiny distal vascular segments and depicting stenosis and also its cause, including atherosclerotic plaque, thrombus, tumor, and anatomic abnormalities. Moreover, MDCT enables detailed evaluation of each bowels segment for evidence of ischemia or infarction.
Findings of AMI included mesenteric arterial or venous thrombus, mesenteric venous gas, pneumatosis intestinalis, bowel-wall thickening, increased or decreased enhancement of the bowel wall, bowel dilatation, mesenteric or per enteric fat stranding, ascites, pneumoperitoneum, and solid organ infarction are easily detected by MSCT.
Advanced CT scanners and expertise in three-dimensional (3D) imaging are becoming increasingly wide spread, opening the door to new opportunities and challenges in the evaluation of patient suspected of having acute mesenteric ischemia.