Evaluation of bowel ischemia with contrast-enhanced US: initial experience.

PURPOSE

To prospectively evaluate the accuracy of contrast material-enhanced ultrasonography (US) in the depiction of bowel ischemia in patients with radiographic evidence of small-bowel dilatation.

MATERIALS AND METHODS

The ethics committee approved this study, and informed consent was obtained from all patients. Fifty-one patients (34 men and 17 women; mean age, 67.1 years) with evidence of small-bowel dilatation at conventional radiography were enrolled. Twenty patients had bowel ischemia (15 cases of bowel strangulation and five of thromboembolism of the superior mesenteric artery) and 31 patients had simple obstruction. After injection of SHU-508A, the most dilated or the least peristaltic bowel segments were imaged at contrast-enhanced power Doppler US (interval, 4 seconds) for 2 minutes. Color signals obtained in the bowel wall were classified as normal, diminished, or absent. Contrast-enhanced US and classification of color signals were performed by a sonologist. The US systems were equipped with 3-12-MHz transducers. Fisher exact test was used to evaluate the significance of the differences between each group of patients, and P < .01 was considered to indicate a significant difference.

RESULTS

The color signals were absent in five patients with superior mesenteric arterial thromboembolism and in seven patients with strangulation, were diminished in five patients with strangulation, and were normal in three patients with strangulation and in 31 patients with simple obstruction. By pooling the absent and diminished color signals together as a diagnostic indicator of bowel ischemia, the sensitivity was 85% (95% confidence interval [CI]: 62.1%, 96.8%), the specificity was 100% (95% CI: 90.8%, 100%), the positive predictive value was 100% (95% CI: 83.8%, 100%), the negative predictive value was 91.2% (95% CI: 76.3%, 98.1%), the likelihood ratio for a positive test result was infinity, and the likelihood ratio for a negative test result was 0.15 (95% CI: 0.032, 0.379).

CONCLUSION

Contrast-enhanced US shows promise for the noninvasive diagnosis of bowel ischemia based on initial experience in patients with radiographic evidence of small-bowel dilatation.