Kyoung Ho Lee MD, Presenter: Nothing to Disclose

Hyo Bin Seo, Abstract Co-Author: Nothing to Disclose

Hyuk Jung Kim, Abstract Co-Author: Nothing to Disclose

So Yeon Kim MD, Abstract Co-Author: Nothing to Disclose

Young Hoon Kim, Abstract Co-Author: Nothing to Disclose

To compare low-dose unenhanced CT with standard-dose intravenous contrast-enhanced CT in the diagnosis of appendicitis.

207 adults with suspected appendicitis underwent both scans with mean effective dose of 4.2 and 8.0 mSv, respectively. Two radiologists retrospectively reviewed thin-section images, by sliding a 5-mm-thick raysum slab. They rated the likelihood of appendicitis and appendiceal visualization using 5- and 3-point scales, respectively, and proposed alternative diagnoses. Likelihood ≥ 3 was considered as a positive diagnosis. Receiver operating characteristic analyses, McNemar tests, and Wilcoxon signed-ranks tests were used.

78 patients had appendicitis. The Az values of the two scans were 0.98 vs. 0.97 (95% CI for the difference, -0.02, 0.03) and 0.99 vs. 0.98 (-0.02, 0.02) for each reader, respectively. The sensitivity was 98.7% vs. 100% (p = 1.00) and 100% vs. 100%. The specificity was 95.3% vs. 93.0% (p = 0.25) and 96.9% vs. 96.9%. The interpretation was indeterminate (score 3) in 0.5% vs. 1.4% (p = 0.63) and 0.5% vs. 0% (p = 1.00). The normal appendix was not visualized in 5.4% vs. 3.9%, (p = 0.63) and 3.9% vs. 2.3% (p = 0.50). None of the patients whose appendix was not visualized had appendicitis. Diagnostic confidence, visualization score for the normal appendix, and correct alternative diagnosis tended to be compromised in the low-dose unenhanced scan, showing significant difference for a reader’s confidence in diagnosing appendicitis (p = 0.004). The two scans were comparable for the diagnosis of appendiceal perforation.

Low-dose unenhanced CT is potentially useful in the diagnosis of appendicitis.

Low-dose unenhanced CT can be recommended for the initial evaluation of adults suspected of having appendicitis.

Lee, K, Seo, H, Kim, H, Kim, S, Kim, Y, Diagnosis of Acute Appendicitis Using Sliding Slab Raysum Interpretation: Low-dose Unenhanced CT vs Standard-dose Intravenous Contrast-enhanced CT.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8004265.html