الفهرس 
Gross Anatomy of small and large bowelOnly 14 pages are availabe for public view
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Abstract
Multi–detector row CT represents a significant advance in CT technology. By allowing thin collimation and rapid scanning, excellent opacification of the mesenteric vessels can routinely be obtained. Better 3D volume sets in turn lead to improved 3D vascular maps, which are useful in cancer staging, surgical planning, and evaluating patients with suspected mesenteric ischemia (Horton et al., 2002).
Indeed, understanding of bowel ischemia and its various causes and pathogenesis and detailed information about the clinical setting of each patient are often important factors in the establishment of an accurate CT diagnosis. Although the CT diagnosis of bowel ischemia may still be difficult if specific CT findings and specific clinical information are lacking, the sensitivity of CT for the diagnosis of acute bowel ischemia (82%) has almost reached the sensitivity of angiography (87.5%), the sensitivities of these two modalities have been directly compared, Given that, in contrast to angiography, CT is able to demonstrate not only vascular occlusions but also bowel wall changes (Horton et al., 2002).
With the introduction of multi–detector row CT, another step forward has been made in the detailed and combined CT examination of mesenteric vessels and bowel walls, However, continuous studies have to show how much the higher speed and resolution, as well as the possibility of multiplanar reconstructions and three-dimensional reformatting available with multi–detector row CT, will increase the value of CT for patients with acute bowel ischemia (Fishman et al., 2001).
Advances in MDCT have significantly improved CT angiography applications in the entire vascular system. The wider availability and lower cost of a CT scan when compared with MR imaging are reasons for its status and preference for vascular imaging (Willmann et al., 2003).
There is no statistical difference between three-dimensional MR angiography and MDCTA in the detection of hemodynamically significant arterial stenosis of the aortoiliac and renal arteries. The review of CT angiography data using post processing techniques requires knowledge of the strength and weakness of the display methods for optimal diagnosis and treatment planning (Willmann et al., 2003).
CT angiography requires the use of three-dimensional reconstruction software not only for extracting vascular information but also for creating three-dimensional images to communicate optimally with referring physicians (Willmann et al., 2003).
MR angiography saves time owing to the ease of post processing data and the lack of overlying bone artifacts; however, it is not suitable for the assessment of vascular calcification. Although the time needed to perform three-dimensional reconstructions and image analysis is significantly longer with CT angiography, it has better patient acceptance when compared with MR angiography (Willmann et al., 2003).
Limitations exist in patients with a history of iodine contrast reaction, which has become rare with the use of low or nonionic contrast media. MR imaging is free from radiation exposure and may be the preferred imaging modality in conditions requiring long-term assessment. Poor kidney function is a relative contraindication. In patients with mild renal dysfunction, adequate hydration and the use of less contrast, supplemented with a saline bolus, may permit adequate scanning (Willmann et al., 2003).