Low-Dose (2-mSv) CT in Adolescents and Young Adults With Suspected Appendicitis: Advantages of Additional Review of Thin Sections Using Multiplanar Sliding-Slab Averaging Technique

Abstract

Objective: The purpose of this study is to assess the advantages of additional multiplanar sliding-slab averaging review of 2-mm-thick (thin) sections over stack review of 5-mm-thick (thick) sections in difficult cases of 2-mSv CT in adolescents and young adults with suspected appendicitis.

Materials and methods: We included 149 patients (mean age, 28.0 years; 61 male patients and 88 female patients) for whom the initial CT reports were inconclusive for the diagnosis of appendicitis. Five independent radiologists retrospectively reviewed the thick sections in the stack mode and then the thin sections using sliding-slab averaging. In each review, they rated the likelihood of appendicitis and the appendix visualization using 5- and 3-point Likert scales, respectively. Diagnostic performance and confidence were compared between the two reviews using ROC analysis, McNemar tests, and Wilcoxon signed-rank tests.

Results: The pooled AUCs were 0.90 and 0.93 for the stack and sliding-slab averaging reviews, respectively (90% CI for the difference, 0.002-0.06; p = 0.087). For the individual readers, the sliding-slab averaging review tended to increase the AUC (range, 0.86-0.93 for stack vs 0.87-0.97 for sliding-slab averaging review), improve the confidence in diagnosing (mean score, 3.6-4.7 vs 3.9-4.7) or ruling out (1.6-2.1 vs 1.5-1.9) appendicitis, reduce indeterminate interpretations (0-15% vs 0-11%), and enhance the normal appendix visualization (1.1-1.7 vs 1.1-1.9), although the differences were not always statistically significant.

Conclusion: Sliding-slab averaging review of thin sections is helpful when the diagnosis of appendicitis is difficult at 2-mSv CT in adolescents and young adults.

Keywords: CT; abdomen; appendicitis; low-dose CT; sliding-slab averaging.