Sumiaki Matsumoto MD, PhD, Presenter: Research grant, Toshiba Corporation

Yoshiharu Ohno MD, PhD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Koninklijke Philips Electronics NV Research grant, Bayer AG Research grant, DAIICHI SANKYO Group Research grant, Eisai Co, Ltd Research grant, Mitsubishi Chemical Holdings Corporation Research grant, Terumo Corporation

Takatoshi Aoki MD, Abstract Co-Author: Nothing to Disclose

Hitoshi Yamagata PhD, Abstract Co-Author: Employee, Toshiba Corporation

Daisuke Takenaka MD, Abstract Co-Author: Nothing to Disclose

Keiko Matsumoto MD, Abstract Co-Author: Nothing to Disclose

Yumiko Onishi MD, Abstract Co-Author: Nothing to Disclose

Kazuro Sugimura MD, PhD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Koninklijke Philips Electronics NV Research grant, Mitsubishi Corporation Research grant, Bayer AG Research grant, Eisai Co, Ltd Research grant, DAIICHI SANKYO Group Research Consultant, Shionogi & Co, Ltd

To directly compare concurrent- and second-read CAD on low-dose CT with second-read CAD on standard-dose CT in terms of the observer performance and reading time for lung nodule detection.

For detection and rating of non-calcified nodules (> 4 mm), 48 pairs of standard-dose (150 mAs) and low-dose (25 mAs) thin-section CT datasets (each pair had been acquired in one examination) were independently read by 4 radiologists (readers 1-4) using a prototype CAD system in three sessions at intervals of two weeks. The gold standard of nodules in the datasets, consisting of 187 nodules, was determined by two board certified chest radiologists beforehand. At one session, for each pair, each reader read: (A) 25 mAs images with concurrent-read CAD; (B) 25 mAs images with second-read CAD; or (C) 150 mAs images with second-read CAD. The order of A-C for 3 sessions was systematically varied across pairs. The observer performances in A, B, and C were mutually compared using jackknife free-response receiver operating characteristic (JAFROC) analysis, and the reading times in A, B, and C were mutually compared using paired t-test for each reader.

The mean (95% confidence interval) of the figure-of-merit values of JAFROC analysis in A, B, and C were 0.72 (0.65, 0.79), 0.71 (0.57, 0.85), and 0.74 (0.64, 0.84); there were no significant difference among the observer performances in A, B, and C (p>0.5). The reading times in A, B, and C were: for reader 1, 117±62 s, 153±87 s, and 152±70 s; for reader 2, 204±85 s, 246±116 s, and 245±99 s; for reader 3, 108±85 s, 134±65 s, and 156±87 s; for reader 4, 180±59 s, 239±110 s, and 248±95 s. For all readers, while there was no significance difference between the reading times in B and C (p>0.05), the reading time in A was significantly shorter than that in B or C (p<0.01).

The observer performance of concurrent- or second-read CAD on low-dose CT was comparable to that of second-read CAD on standard-dose CT. The reading time in concurrent-read CAD on low-dose CT was significantly shorter than that in second-read CAD on low- or standard-dose CT.

For lung nodule detection, concurrent-read CAD on low dose CT can allow the same level of accuracy and the reduction of reading time, as compared to second-read CAD on low- and standard-dose CT.

Matsumoto, S, Ohno, Y, Aoki, T, Yamagata, H, Takenaka, D, Matsumoto, K, Onishi, Y, Sugimura, K, Concurrent and Second-Read Computer-aided Detection (CAD) for Lung Nodules on Low-Dose CT: Comparison with Second-Read CAD on Standard-Dose CT.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9003981.html