Improving the false-negative rate of CT in acute appendicitis—Reassessment of CT images by body imaging radiologists: A blinded prospective study

Abstract 

Purpose

To compare the accuracy of computed tomography (CT) analyzed by individual radiology staff members and body imaging radiologists in a non-academic teaching hospital for the diagnosis of acute appendicitis.

Patients and methods

In a prospective study 199 patients with suspected acute appendicitis were examined with unenhanced CT. CT images were pre-operatively analyzed by one of the 12 members of the radiology staff. In a later stage two body imaging radiologist reassessed all CT images without knowledge of the surgical findings and without knowledge of the primary CT diagnosis. The results, independently reported, were correlated with surgical and histopathologic findings.

Results

In 132 patients (66%) acute appendicitis was found at surgery, in 67 patients (34%) a normal appendix was found. The sensitivity of the primary CT analysis and of the reassessment was 76% and 88%, respectively; the specificity was 84% and 87%; the positive predictive value was 90% and 93%; the negative predictive value was 64% and 78%; and the accuracy was 78% and 87%.

Conclusion

Reassessment of CT images for acute appendicitis by body imaging radiologists results in a significant improvement of sensitivity, negative predictive value and accuracy. To prevent false-negative interpretation of CT images in acute appendicitis the expertise of the attending radiologist should be considered.

Keywords: Acute appendicitis, CT, Diagnostic accuracy