Amy Elizabeth Musk MD, Presenter: Nothing to Disclose

Khan Mohammad Siddiqui MD, Abstract Co-Author: Nothing to Disclose

Ryan Moffitt, Abstract Co-Author: Nothing to Disclose

Stacy Chia MD, Abstract Co-Author: Nothing to Disclose

Nabile M. Safdar MD, Abstract Co-Author: Nothing to Disclose

Bruce Ian Reiner MD, Abstract Co-Author: Nothing to Disclose

Thorsten Roger Fleiter MD, Abstract Co-Author: Nothing to Disclose

Robert Daniel Pugatch MD, Abstract Co-Author: Nothing to Disclose

Charles Stephen White MD, Abstract Co-Author: Nothing to Disclose

Eliot Lawrence Siegel MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To evaluate the impact of two additional dual energy subtraction images compared with traditional 2 view chest radiographs on recommendations for follow up CT

139 patients referred for chest CT have been enrolled into our IRB approved protocol. Each patient received a chest radiograph using a direct digital receptor (DR) system with an additional image acquired at a lower energy which was used to produce a total of four images using DES (dual energy subtraction). The images included a conventional PA and lateral, as well as PA calcium subtracted (removes overlying bony structures which has been previously shown to improve non-calcified nodule detection) and a calcium enhanced image (theoretically improves determination of calcium content of nodules). All images from the first 27 patients (age 55-85) have been analyzed to date. After review of the images using DR either with or without DES, radiologists were asked to determine whether the nodules were calcified and whether they would recommend a follow-up CT. Conventional dose non-contrast chest CT served as the gold standard of reference.

For non-calcified nodules, follow up CT was recommended in 35.4% of the cases where DR was reviewed without DES with a true positive rate of 35%. Follow up CT was recommended in only 25% of cases with a true positive rate of 20%. For nodules that were found to contain calcification on CT, follow up CT was recommended in 34.2% of cases in which DR only was reviewed with a 100% true positive rate for these cases. For studies reviewed with both DR and DES, 22.8% had recommendations for follow up CT and the true positive rate for these was also 100%.

The addition of dual energy subtraction resulted in a significant (p=.03) decrease in the recommendation rate for follow up CT studies for both calcified and non-calcified nodules presumably due to its enhanced ability to determine whether a nodule contains calcium.

A.E.M.,K.M.S.,E.L.S.,B.I.R.,R.M.,S.S.: This study was supported by a research grant from General Electric

Musk, A, Siddiqui, K, Moffitt, R, Chia, S, Safdar, N, Reiner, B, Fleiter, T, Pugatch, R, White, C, Siegel, E, et al, , Impact of Dual Energy Subtraction Chest Images on Recommendations for Radiology Follow-up.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4418996.html