Akira Kurata, Presenter: Nothing to Disclose

Anoeshka Shashikala Dharampal MD, Abstract Co-Author: Nothing to Disclose

Admir Dedic MD, Abstract Co-Author: Nothing to Disclose

Pim Feyter MD, PhD, Abstract Co-Author: Nothing to Disclose

Marcel L. Dijkshoorn RT, Abstract Co-Author: Consultant, Siemens AG

Gabriel P. Krestin MD, PhD, Abstract Co-Author: Consultant, General Electric Company Research Grant, General Electric Company Research Grant, Bayer AG Research Grant, Siemens AG Speakers Bureau Siemens AG

Koen Nieman MD, Abstract Co-Author: Nothing to Disclose

Coronary artery calcium (CAC) score by computed tomography (CT) is widely used for cardiovascular risk stratification. Iterative reconstruction algorithms reduce image noise and potentially decrease radiation exposure. We evaluated the influence of sonogram-affirmed iterative reconstruction (SAFIRE) on the CCS score.

In 70 consecutive patients, who underwent CAC imaging by 128-slice dual-source 128-slice CT, CAC volume, mass and Agatston score were calculated from images reconstructed by filtered back projection (FBP) without and with incremental degrees of iterative reconstruction (SAFIRE algorithm: 10-50%). We used the repeated measuring test and the Steel-Dwass test for multiple comparisons of values and the difference ratio among different SAFIRE groups, using the FBP (0% SAFIRE) as reference.

The median Agatston score (range) decreased with incremental IR: 163 (0.1 ~ 3393.3), 158.4 (0.3 ~ 3079.3), 137.7 (0.1 ~ 2978.0), 120.6 (0 ~ 2783.6), 102.6 (0 ~ 2468.4), and 84.1 (0 ~ 2186.9) for 0% (FBP), 10%, 20%, 30%, 40%, and 50% SAFIRE, respectively (Figure 1; P<0.05). In comparison with FBP, CAC parameters (median) decreased proportionally to the component ratio of SAFIRE algorithm CAC volume from 8.1% to 47.7%, CAC mass from 5.3% to 44.7% and CAC Agatston score from 7.3% to 48.4% for increasing SAFIRE 10% to 50%, respectively (P<0.05). High-grade SAFIRE resulted in the disappearance of detectable calcium in 3 cases with low calcium burden.

SAFIRE noise reduction techniques significantly affected the coronary calcium quantification, with potential clinical consequences.

Iterative reconstruction techniques should not be used, because it significantly reduced quantitative coronary calcium quantification.

Kurata, A, Dharampal, A, Dedic, A, Feyter, P, Dijkshoorn, M, Krestin, G, Nieman, K, Impact of Iterative Reconstruction on CT Coronary Calcium Quantification.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13019518.html