Interpretation of Abdominal CT Findings in Patients Who Develop Acute on Chronic Mesenteric Ischemia.

Background: We studied whether ischemia-specific computed tomography (CT) findings are consistently detectable in patients who develop acute on chronic mesenteric ischemia (AOCMI), whereas absent in chronic mesenteric ischemia (CMI).

Methods: Consecutive patients with symptomatic angiography-verified atherosclerotic obstruction of the superior mesenteric artery (SMA) were categorized as AOCMI (n = 27) or CMI (n = 20). Three experienced radiologists blindly evaluated the contrast-enhanced CTs for vascular and intestinal findings. Kappa statistics was used to test interobserver agreement.

Results: Two observers had substantial agreement (k = 0.66) that two thirds of AOCMI patients showed ischemia-specific CT findings (decreased bowel wall enhancement, pneumatosis, or thrombotic SMA clot); the third observer agreed only fairly regarding pneumatosis and thrombosis (k = 0.3-0.4). All observers had substantial agreement (k = 0.65-0.71) that most patients with AOCMI had unspecific intestinal findings such as mesenteric fat stranding in up to 96%, bowel lumen dilatation in 93%, and bowel wall thickening in 70%, while only few patients with CMI had such findings (due to chronic ischemic colitis) (P < 0.001).

Conclusion: One third of AOCMI patients presented without any ischemia-specific CT signs. However, any intestinal abnormality in CT together with SMA obstruction should raise suspicion of intestinal ischemia. Furthermore, clinicians need to be aware of the interobserver variability in the CT interpretation.