The findings of venous mesenteric ischemia (VMI) are well described in the literature but there is a condition, the reperfusion after acute arterial occlusion (I\R condition), that seems to show similar features.The aim of this study is to explore similarities and differences between VMI and I\R in an experimental model studied by a 7 Tesla Magnetic Resonance Imaging (7T MRI) system, establishing radiological findings that may help to distinguish between these 2 conditions and select the correct therapeutic approach.

Thirty Adult Sprague-Dawley rats were divided in two different groups that underwent different surgical models and a different monitoring of ischemic damage. Group I underwent to superior mesenteric vein (SMV) ligation whereas Group II underwent superior mesenteric artery (SMA) ligation followed by reperfusion after 1 hour. At different time-points (1 hour, 2 hours, 4 hours, 6 hours, 8 hours) 3 rats for each group were imaged with 7T MRI, euthanized and macroscopically\histologically analysed.

In the first hour it was not possible to detect MRI findings that helped in distinguishing these two conditions: in both groups hyper-intense signal in T2-W sequences in the intestinal wall was detected, as well as the presence of free fluid. These findings are concordant with the pathological analysis that showed chromatic change (from pink to dark red) of the bowel (Fig. 1). Histological analysis showed a patchy inflammatory pattern and vascular congestion with the development of supepithelial edema (Grunhagen’s space). In the second hour,...

Results of this study, derived from an animal model, suggest that the analysis of mesentery and the presence\absence of the HRI analyzed by MRI may help in distinguishing between these two conditions (Fig. 4).

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