title: Computed tomography diagnosis of acute appendicitis: advantages of reviewing thin-section datasets using sliding slab average intensity projection technique.
abstract: OBJECTIVE
  We sought to compare sliding slab mode and standard stack mode in the computed tomography (CT) diagnosis of acute appendicitis.
  
  
  METHODS
  Contrast-enhanced CT was performed in 85 patients, 35 of whom had appendicitis. Four readers retrospectively reviewed 5-mm thick transverse sections (4-mm increment) using the stack mode and 2-mm thick sections (1-mm increment) with the sliding slab, average intensity projection. The sliding slab mode started with a 5-mm thick transverse slab, but the readers were encouraged to change the viewing angle and the slab thickness.
  
  
  RESULTS
  In sliding slab mode, the readers changed the viewing angle in 89 of 340 observations (24%) and decreased the slab thickness in 26 observations (8%). Although the receiver operating characteristic analysis did not show a significant difference (P = 0.18), the sliding slab mode enhanced the pooled sensitivity (93.6% vs. 98.6%, P = 0.02), specificity (92.0% vs. 97.5%, P = 0.01), and mean confidence for the diagnosis (P < 0.001) or exclusion (P = 0.002) of acute appendicitis; reduced inconclusive interpretations (5.6% vs. 1.8%, P = 0.01); and visualized the appendix more clearly (P < 0.001).
  
  
  CONCLUSIONS
  Compared with the stack mode, the sliding slab mode enhances diagnostic confidence and more clearly visualizes the appendix.
authors.affiliation: Department of Radiology, Seoul National University Bundang Hospital, Korea.
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Kim
authors.forename: Seokyung
authors.initials: S
authors.lastname: Hahn
authors.forename: Kyung Won
authors.initials: KW
authors.lastname: Lee
authors.forename: Tae Jung
authors.initials: TJ
authors.lastname: Kim
authors.forename: Sung-Bum
authors.initials: SB
authors.lastname: Kang
authors.forename: Joong Ho
authors.initials: JH
authors.lastname: Shin
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D001064:Appendicitis / Q000000981:diagnostic imaging*; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media