Experimental Study Of Spiral CT Diagnosis Of Acute Mesenteric Ischemia

Purpose: To investigate the potential value of spiral CT in diagnosing acutemesenteric ischemia (AMI) by comparing the findings of spiral CT withpathologic examinations after establishing canine's acute mesenteric ischemicmodel.Material and Methods:1 8 beagles were divided into two groups at random: three-hour ischemic group and six-hour ischemic group.2 After successfully punctured into the right femoral artery through seldinger's technique, absolute ethanol was selectively injected into the superior mesenteric artery(SMA) for embolization via a 4 F Cobra catheter.3 Unenhaced CT study was respectively performed at 1, 2h after embolization in all animals, Unenhaced and contrast-enhanced CT study were performed before embolization and at 3, 6h in two groups(the former didn't take any examination at 6h) .4 The CT findings were concluded at different periods of time. The contrast-enhanced degree of thickened and nonthickened bowel loops were evaluated after interventional operation, while the contrast-enhanced degree of bowel loops were also evaluated preoperation. Stastistic analysis was then taken.5 The abdominal cavity was inspected after a midline laparotomy, then three abnormal and one normal bowel biopsies were examined by standard HE slide preparations.Results:1 The AMI's models were successfully established in all eight beagles.2 CT findings in canine's model were made up as follows: mesenteric stranding, bowel-wall thickening, luminal dilatation and fluid-filled, intramural gas, portal venous gas, ascites; target-sign or halo-sign seen atcontrast-enhanced CT.3 The CT appearances weren't same in different periods: mesenteric stranding occurred at 1h after embolization in every beagle; both bowel-wall thickening and luminal dilatation were the early findings; intramural gas, portal venous gas and ascites occurred lately for most of animals.4 The contrast-enhanced degree of bowel walls especially the thickened bowel after embolization were significantly declined than that of preoperation, and the contrast-enhanced degree of thickened bowels in six-hour group were significantly declined than three-hour group.5 All animals developed microscopic and gross changes of bowel ischemia. Ischemic injuries were limited to the intestinal mucosa in two cases and extended into submucosal and muscular layers in other two animals in three-hour group; while transmural bowel wall necrosis was developed in three animals and submucosal injury occurred in only one animal in six-hour group.Conclusions:1 Animal models with acute mesenteric ischemia can be established by the technique of the selective catheterization with absolute ethanol's injection.2 The early CT findings consist of mesenteric stranding, bowel-wall thickening, target-sign or halo-sign luminal dilatation and fluid-filled.3 The CT findings of later stage consist of intramural gas, portal venous gas, ascites.4 Contrast-enhanced CT can judge bowel wall's ischemia or necrosis directly: the lack of wall enhancement suggests transmural bowel wall necrosis; gentle or middle degree of wall enhancement suggests bowel ischemia.5 Spiral CT can make the early diagnosis of AMI accurately and judge their different stage.