الفهرس 
Anatomy of the mesenteric vesselsOnly 14 pages are availabe for public view
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Abstract
Acute mesenteric ischemia (AMI) is a syndrome in which inadequate blood flow through the mesenteric circulation causes ischemia and eventual gangrene of the bowel wall.
AMI may be classified either as arterial or venous disease. Arterial disease may be subdivided into occlusive mesenteric arterial ischemia and non occlusive mesenteric arterial ischemia. Occlusive mesenteric arterial ischemia may be further subdivided into acute mesenteric arterial embolus and acute mesenteric arterial thrombosis. Venous disease takes the form of mesenteric venous thrombosis.
The different types of AMI share many similarities and a common pathway which is bowel infarction and death if not properly treated.
Mesenteric arterial emboli accounts for 50% of the causes of acute mesenteric ischemia and is usually caused by an embolus of cardiac origin.
Thrombosis of a mesenteric artery is the end result of atherosclerotic stenosis, and these patients often give a history of abdominal angina before the acute thrombosis occurs.
Non occlusive ischemia is a condition in which the mesenteric arteries and veins are patent, but flow through them is too slow to deliver enough oxygenated blood to the intestine. The cause is usually decreased cardiac output from any cause.
Mesenteric venous thrombosis is an uncommon but potentially lethal cause of bowel ischemia. It accounts for a relatively small percentage of such cases, about 15% - 20%, but remains an important cause of acute bowel infarction.
MDCT technology has dramatically improved the performance of CT by allowing rapid volumetric data acquisition. It provides increased longitudinal spatial resolution over a large anatomic volume. from the volume data, retrospective thin or thick sections; sagittal, coronal, or curved multiplanar reformatted images; and CT angiograms with 2D or 3D visualization can be obtained. The rapid scanning capability of this technique coupled with IV bolus contrast injection substantially optimizes scan timing to allow both the arterial and venous phases to be imaged. These advantages are helpful in identifying the site, level, and cause of bowel ischemia by showing abnormalities in the bowel wall, mesentery, and mesenteric vessels. With these developments, the ability of CT for diagnosing mesenteric ischemia has recently been reported to have a sensitivity of approximately 90%.
Acute bowel ischemia provides various morphologic and attenuation abnormalities on CT images in the bowel wall, mesentery and mesenteric vessels. These variations depend on the pathogenesis of bowel ischemia as well as the acuteness, duration, site, and extent of the ischemic attack and the state of the collateral circulation. Superimposed bowel wall infection and the presence of perforation may also affect the CT appearances of acute bowel ischemia.
MDCT is a safe, fast and easy procedure that does not have the complications of catheterization of conventional angiography with its associated morbidity and mortality. MDCT angiography can be performed as an outpatient non invasive procedure with no need for hospitalization that is necessary after conventional angiography.
Conclusion:-
MDCT is the imaging tool of choice in diagnosis of mesenteric ischemia. It provides visualization of pathological conditions of the mesenteric vasculature in addition to delineation of the extra vascular intestinal abnormalities and can help in detection of the primary cause of intestinal ischemia beside its rule in ruling out other causes of acute abdomen in an easy, fast and non invasive manner.