To evaluate the accuracy of multi-detector row helical computed tomography (MDCT) with intravenous contrast material and without oral contrast material in distinguishing perforated appendicitis from nonperforated appendicitis.

From Jan 2000 to Dec 2002, findings of MDCT with intravenous contrast material and without oral contrast material in 103 consecutive patients with surgically and pathologically proven appendicitis were reviewed. Original axial slices at 3-mm or 2-mm collimation and 1.5-mm or 1-mm intervals were viewed by cine-mode observation. The presence of five specific findings (focal defect in appendiceal wall enhancement, abscess, phlegmon, extraluminal air, and extraluminal appendicolith) was evaluated. The presense of additional findings (intraluminal appendicolith,identification of the vermiform appendix, appendiceal diameter, positive thickening of cecal wall) were also evaluated. Snsitivity, specificity, and accuracy of each finding in the diagnosis of perforation were calculated.

The perforated appendicitis comprised 41 patients and the non-perforated appendicitis comprised 62 patients.A focal defect in appendiceal wall enhancement was clearly visualized in 39 patients in the perforated group. Only two patients in the non-perforated group were false-positives for a focal appendiceal wall defect.Sensitivity, specificity, and accuracy of this finding in the diagnosis of perforation were 95.1%, 96.8% and 96.1%, respectively. Sensitivity for extraluminal air, abscess, and extraluminal appendicolith were 22%, 39%, and 32%, respectively. These findings were not found in patients with non-perforated appendicitis.Phlegmon was seen in 16 patients in the perforated group and 3 patients in the non-perforated group. Sensitivity, specificity, and accuracy of phlegmon in the diagnosis of perforation were 39%, 95.2%, and 72.8%, respectively.
In additional findings,significant difference was found only in the presence of cecal wall thickening.

MDCT can accurately distinguish between perforated and nonperforated appendicitis. Detecting focal defect of appendiceal wall enhancement by cine-mode display of thin slice axial slices is essential for accurate diagnosis.