Diagnostic performance of CT in the detection of intestinal ischemia associated with small-bowel obstruction using maximal attenuation of region of interest.

OBJECTIVE: The purpose of this study was to assess the diagnostic performance of CT in the detection of intestinal ischemia associated with small-bowel obstruction using the maximal attenuation of a region of interest (ROI).

MATERIALS AND METHODS: Abdominal CT scans of 60 patients with small-bowel obstruction were retrospectively reviewed. The reference standard of the clinicopathologic groups was classified into four categories: no bowel necrosis, mucosal-submucosal necrosis, superficial muscle necrosis, and transmural necrosis. The viability of the small bowel on CT was evaluated by visual assessment using five categories (i.e., definitely intestinal ischemia, probably intestinal ischemia, possibly intestinal ischemia, equivocal CT results, and no intestinal ischemia) and by measurement of the maximal attenuation of an ROI at selected obstructed small-bowel loops on contrast-enhanced and unenhanced CT scans. Diagnostic performances were evaluated by one-way analysis of variance and receiver operating characteristic (ROC) curve analysis.

RESULTS: The sensitivity, specificity, positive and negative predictive values, and accuracy of visual assessment for intestinal ischemia were 91.7% (33/36), 66.7% (16/24), 80.5% (33/41), 84.2% (16/19), and 81.7% (49/60), respectively. The maximal attenuation of the ROIs on contrast-enhanced CT and the subtraction value between the maximal attenuation on contrast-enhanced CT and that on unenhanced CT scans at selected bowel were significantly different according to clinicopathologic group (p < 0.001). The area under the ROC curve of the maximal attenuation subtraction values between contrast-enhanced and unenhanced CT scans (0.995) was higher than that of visual assessment (0.908) for the detection of intestinal ischemia.

CONCLUSION: The quantification of bowel wall enhancement using the maximal attenuation of an ROI was a reliable and useful method for the diagnosis of intestinal ischemia and showed good correlation with pathology results.