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

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.

Comparison of CT and sonography in the diagnosis of acute appendicitis: a blinded prospective study.

OBJECTIVE: Our objective was to compare the accuracy of CT and sonography in a general community teaching hospital for the diagnosis of acute appendicitis in patients with suspected acute appendicitis. SUBJECTS AND METHODS. In this prospective study, 199 consecutive patients with clinical signs and symptoms of acute appendicitis were examined with sonography (graded compression technique) and CT (focused unenhanced single-detector helical CT [5-mm section thickness]. CT was performed from the L2 vertebral body to the pubic symphysis, and no patients were given oral, rectal, or IV contrast medium. The primary sonographic criterion for diagnosing acute appendicitis was an incompressible appendix with a transverse outer diameter of 6 mm or larger with incompressible periappendicular inflamed fat with or without an appendicolith. The primary CT criterion for diagnosing acute appendicitis was the identification of an appendix with a transverse outer diameter of 6 mm or larger with associated periappendiceal inflammatory changes. The results, independently reported, were correlated with surgical and histopathologic findings. RESULTS: One hundred thirty-two patients had acute appendicitis at surgery, and 67 patients did not. The sensitivity of CT and sonography was 76% and 79%, respectively; the specificity was 83% and 78%; the accuracy was 78% and 78%; the positive predictive value was 90% and 87%; and the negative predictive value was 64% and 65%. CONCLUSION: Unenhanced focused single-detector helical CT and graded compression sonography performed in a general community teaching hospital by both body imaging radiologists and general radiology staff members have a similar accuracy for the diagnosis of acute appendicitis.

Successful emergency stenting of acute ruptured false iliac aneurysm.

A 75-year-old man complaining of acute abdominal pain, 1 month after elective surgical repair of an abdominal aortic aneurysm by an aortabi-iliac bypass graft, was referred and admitted to the emergency room. Imaging by sonography and computed tomography scan revealed a ruptured iliac pseudoaneurysm at the right iliac anastomotic site with associated large retroperitoneal hematoma. We inserted a self-expanding covered Z-stent graft by a transfemoral approach and the iliac anastomotic pseudoaneurysm was successfully excluded. Our case demonstrates the possibilities of an endovascular approach for providing a fast, efficient and less aggravating procedure in order to treat these life-threatening conditions.