Christopher Trimble MD, MBA, Presenter: Nothing to Disclose

Ganesh Saiprasad MS, Abstract Co-Author: Nothing to Disclose

James J. Filliben, Abstract Co-Author: Nothing to Disclose

Alden A. Dima MS, Abstract Co-Author: Nothing to Disclose

Adele Peskin, Abstract Co-Author: Nothing to Disclose

Eliot L. Siegel MD, Abstract Co-Author: Research grant, General Electric Company Speakers Bureau, Siemens AG Board of Directors, Carestream Health, Inc Research Grant, XYBIX Systems, Inc Research Grant, Steelcase, Inc Research Grant, Anthro Corp Research Grant, RedRick Technologies Inc Research Grant, Evolved Technologies Corporation Research Grant, Barco nv Research Grant, Intel Corporation Research Grant, Dell Inc Research Grant, Herman Miller, Inc Research Grant, Virtual Radiology Research Grant, Anatomical Travelogue, Inc Medical Advisory Board, Fovia, Inc Medical Advisory Board, Vital Images Medical Advisory Board, McKesson Corporation Medical Advisory Board, Carestream Health, Inc Medical Advisory Board, Bayer AG Research, TeraRecon, Inc Medical Advisory Board, Bracco Group Researcher, Bracco Group Medical Advisory Board, Merge Healthcare Incorporated Medical Advisory Board, Microsoft Corporation Researcher, Microsoft Corporation

Ehsan Samei PhD, Abstract Co-Author: Research Grant, Siemens AG Research Grant, General Electric Company Research Grant, Carestream Health, Inc Consultant, KUB Technologies, Inc

Olav Christianson, Abstract Co-Author: Nothing to Disclose

Joseph Jen-Sho Chen MD, Abstract Co-Author: Advisory Board, Bayer AG

Zhitong Yang PhD, Abstract Co-Author: Nothing to Disclose

Commercial CT vendors have suggested a major positive impact on image quality with the use of iterative reconstruction (IR) and that scanning at lower doses can be performed with equivalent image quality. Unaware of prior efforts of others to conduct a similar study, we set out to perform a blinded quantitative evaluation of the relative impact of IR on image quality using a forced choice reader study paradigm with three CT vendors at three dose levels.

Using module 2 from the ACR CT phantom accreditation series, CT images were acquired using three commercial CT scanners at 20, 12, and 7.2 mGy. Images were reconstructed using vendor specific filtered back projection (FBP) and IR. For each of the 18 unique modality/dose/algorithm combinations, 50 representative images were obtained for a total of 900 images. A forced choice detection reader study involving 12 radiologists and physicist participants at two sites was performed using a purpose built workstation. The 900 DICOM images were presented in random order in one of two orientations. Readers were asked whether the phantom was flipped on its vertical axis. A total of 10,800 responses were recorded and analyzed.

Overall vendor aggregated accuracy rates were 85.3% IR and 79.5% FBP at 20 mGy, 69.6% IR and 62.3 FBP at 12 mGy, and 60.7% IR and 56.9% FBP at 7.5 mGy. Vendor A accuracy rates were: 90.5 % IR and 83.8 FBP at 20 mGy, 75.3% IR and 61.7% FBP at 12mGy, 67.3% IR and 59.3% FBP at 7.5 mGy. Vendor B algorithm accuracy rates: 84.5% IR and 80.2 FBP at 20 mGy, 65.8% IR and 61.8% FBP at 12mGy, 55.7% IR and 55.7% FBP at 7.5 mGy. Vendor C algorithm accuracy rates: 81% IR and 74.5% FBP at 20 mGy, 67.7% IR and 63.3% FBP at 12mGy, 59% IR and 55.7% FBP at 7.5 mGy.

Iterative reconstruction yielded superior detection of the low contrast objects compared with FBP at all tested radiation doses p<0.01. Signal detection accuracy at 7.5 mGy for an IR image was statistically indistinguishable from FBP at a dose of 12 mGy. There was substantial variation among the tested vendors in the impact of IR on image quality with one vendor achieving a much higher improvement than the other two.

The use of IR resulted in substantial improvement over FBP, but improvement varied according to the vendor. A forced choice reader phantom study model is promising to assess the impact of IR.

Trimble, C, Saiprasad, G, Filliben, J, Dima, A, Peskin, A, Siegel, E, Samei, E, Christianson, O, Chen, J, Yang, Z, Multi-Institutional Quantitative Evaluation of the Impact of IR for Three Commercial CT Vendors at Three Dose Levels Using Forced Choice Reader Study.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12030742.html