Biphasic CT with mesenteric CT angiography in the evaluation of acute mesenteric ischemia: initial experience.

PURPOSE To evaluate the sensitivity and specificity of biphasic computed tomography (CT) with mesenteric CT angiography in the diagnosis of acute mesenteric ischemia (AMI). MATERIALS AND METHODS Sixty-two patients with clinically suspected AMI underwent prospective imaging with biphasic multi-detector row CT. Mesenteric CT angiography was performed with 1.25-mm collimation starting 25 seconds after 140 mL of intravenous contrast agent was administered at a rate of 4 mL/sec, followed by portal venous phase imaging with 5-mm collimation and a 60-70-second delay. CT angiograms were reconstructed with multiplanar (including transverse), maximum intensity projection, and volume-rendered techniques. All scans were evaluated prospectively by two independent radiologists for CT evidence of ischemia. AMI was confirmed with surgical or pathologic proof in 25 of 26 patients. In one patient, AMI was confirmed with clinical findings and serial CT examinations. In patients with AMI, sensitivity and specificity of each CT sign were calculated retrospectively by using patients who did not have intestinal ischemia as a control group. CT criteria that optimized sensitivity and specificity for the diagnosis of AMI were then developed. RESULTS AMI was diagnosed in 26 patients. The CT angiogram depicted arterial disease in eight patients and altered care in five. A finding of any one of pneumatosis intestinalis, venous gas, superior mesenteric artery occlusion, celiac and inferior mesenteric artery occlusion with distal SMA disease, or arterial embolism was 100% specific but only 73% sensitive. Alternatively, a finding of bowel wall thickening in addition to focal lack of bowel wall enhancement, solid organ infarction, or venous thrombosis was 50% sensitive and 94% specific. By using either of these criteria for the diagnosis, a sensitivity of 96% and a specificity of 94% can be achieved. CONCLUSION Biphasic CT with mesenteric CT angiography is effective in the diagnosis of AMI.