Erik K. Paulson MD, Presenter: Research Consultant, Siemens AG Stockholder, ZONARE Medical Systems, Inc

Amy Neville MD, Abstract Co-Author: Nothing to Disclose

Stephen I. Zink MD, Abstract Co-Author: Researcher, Bayer AG, Montville, NJ

Joao F. Tannus MD, Abstract Co-Author: Nothing to Disclose

Maxwell Bret Abbott MD, PhD, Abstract Co-Author: Nothing to Disclose

Matthew B. McCarthy MD, Abstract Co-Author: Nothing to Disclose

Donald P. Frush MD, Abstract Co-Author: Research Consultant, General Electric Company Research Consultant, Siemens AG

Our purpose was to prospectively compare reader agreement of a range of reduced dose 64-slice MDCT images to standard dose 64 MDCT images for the diagnosis of acute appendicitis.

One hundred and six (84 negative, 22 positive) consecutive patients with suspected acute appendicitis underwent a conventional oral and IV contrast enhanced abdomen and pelvic 64-slice MDCT (GE). With a proprietary noise addition tool (supported by GE), noise was then introduced to simulate a 25%, 50%, and 75% reduction in mA (“dose” reduction). Three blinded readers interpreted the original and simulated dose scans (n=424) in random order for (1)identification of the appendix, (2)determination that appendix was normal, (3)presence of acute appendicitis, as well as other findings related to the clinical presentation.

For all patients, mean percent (range) agreement between readers on identification of the appendix on the original, and 25%, 50%, and 75% reduced-dose scans respectfully was: 86% (84-88%), 81% (78-83%), 77% (75-78%), 77% (73-78%). For patients without appendicitis mean agreement on determination that the appendix was normal for the original and 25%, 50%, and 75% reduced-dose scans was: 91% (86-96%), 91% (88-96%), 90% (84-93%), 84% (76-85%). For patients with appendicitis, mean agreement on appendicitis on the original, and 25%, 50%, and 75% reduced dose scans was: 100%, 97% (92-100%), 100%, 100%.

Simulated tube current reduction is a useful tool for systematic evaluation of diagnostic accuracy at low radiation dose, including possible appendicitis. In patients with suspected acute appendicitis, there is excellent agreement between readers on the presence or absence of a diseased appendix even at significantly reduced mA (radiation dose). These results are promising and suggest that dose reduction can be achieved without significant loss in reader agreement in this common disorder.

Our results are promising and suggest that in the clinical setting of acute appendicitis dose reduction can be achieved without significant loss in reader agreement.

Paulson, E, Neville, A, Zink, S, Tannus, J, Abbott, M, McCarthy, M, Frush, D, Comparison of Reader Agreement of Conventional and Simulated Reduced mA (Dose) 64-Slice MDCT for the Diagnosis of Acute Appendicitis.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9006845.html