[Multidetector-row CT evaluation of acute bowel ischemia induced by embolization of superior mesenteric artery in experimental porcine models]

Abstract

Objective: To evaluate the application of multi-detector row CT (MDCT) and CT angiography (CTA) for detecting early signs of acute bowel ischemia (ABI) in experimental porcine models.

Methods: Twelve pigs were assigned to four groups with 3 in each group. The digital subtraction angiography of superior mesenteric artery (SMA) and the embolization of branches of SMA with gelatin sponge and blood clot were performed by percutaneous transfemoral artery puncture and catheterization. MDCT pre- and post-contrast scanning in the arterial, venous and delay phase and CTA with three-dimensional reconstruction were carried out at pre-operation, 3 h, 6 h, 9 h, and 12 h after occlusion. The normal mesenteric vascular anatomy, arterial occlusion, mesentery and bowel changes, and dynamic change were evaluated.

Results: ABI changes were identified pathologically in all the 12 experimental pigs, and the severity of ischemia increased over time after embolization. CTA showed all 57 embolized branches of SMA and 29 of 34 unoccluded arterial branches with 5 false-positive vessel occlusions. The sensitivity and specificity of CTA were 100% and 85.3%, respectively. Thin-slab maximum intensity projection (TSMIP) revealed the disappearance of distal comb-like vessel branches and brush-like vasa recta, which were clearly delineated in the normal bowel segments. Using this criterion, TSMIP correctly defined 23 of 24 ischemic bowel segments and all the 12 normal bowel segments with a sensitivity of 95.8% and a specificity of 100%.

Conclusions: MDCT and CTA reliably define normal and occluded mesenteric vessels in the pig. It can easily detect ischemic bowel segment by identified early changes of ischemia. The early direct ischemic signs are occluded vessels, the disappearance of distal comb-like branches or brush-like vasa recta, and poor bowel enhancement. The early indirect sign is bowel dilatation with fluid collection.