Evaluation of the maximum depth of intraluminal appendiceal fluid to diagnose appendicitis with a 64-detector row CT scanner

The objective of this study was to investigate whether the criterion "maximum depth of intraluminal appendiceal fluid greater than 2.6 mm" ("DEPTH >2.6 mm"), with the use of 64-detector row computed tomography, is useful to diagnose appendicitis.

We retrospectively evaluated 0.68-mm-thick images of 2894 intravenously enhanced abdominal-pelvic computed tomography using the following criteria: (1) appendiceal wall thickness greater than 3 mm, (2) appendiceal wall enhancement, (3) focal cecal wall thickening, (4) adjacent lymphadenopathy greater than 5 mm, (5) appendicolith, (6) periappendiceal inflammation, and (7) the new criterion, DEPTH >2.6 mm. Of the 2894 images, 1013 were classified into normal group (including 622 distended [diameter >6 mm] but normal appendices without adjacent lesions), modified group (235 distended normal appendices modified with adjacent lesions), proven-appendicitis group (82 operatively proven appendicitis cases), and clinical-appendicitis group (62 clinically certified appendicitis cases).

The new criterion, DEPTH >2.6 mm, demonstrated both higher sensitivities and higher specificities in all groups (>90%), although this criterion showed lower specificities than some conventional criteria. In contrast, conventional criteria showed lower sensitivities or lower specificities (<60%) in one or more of these groups.

DEPTH >2.6 mm is particularly useful for differentiating appendicitis from distended normal appendix.