Francois Pontana MD, Presenter: Nothing to Disclose

Dominique Moureau, Abstract Co-Author: Nothing to Disclose

Bernhard Schmidt PhD, Abstract Co-Author: Employee, Siemens AG

Kanna Yasunaga MD, Abstract Co-Author: Nothing to Disclose

Jacques Remy MD, Abstract Co-Author: Research Consultant, Siemens AG

Martine J. Remy-Jardin MD, PhD, Abstract Co-Author: Research Grant, Siemens AG

The main objective was to compare image quality of low-dose images reconstructed with a raw-data-based iterative reconstruction algorithm (Sinogram Affirmed Iterative Reconstruction; SAFIRE) with standard-dose filtered back projection (FBP) CT. The secondary objective was to evaluate the impact of SAFIRE on the detection of CT features of lung infiltration.

50 consecutive dual-source chest CT datasets, acquired in the conditions of routine clinical practice (120 kVp; 110 mAs) with (a) both tubes set at similar energy, and (b) the total reference mAs split up in a way that 40% of the reference mAs was applied to tube A (i.e., 44 eff mAs) while 60% of the reference mAs was applied to tube B (i.e., 66 eff mAs) with a 4D dose modulation. Two series of images were generated: (a) full-dose images (generated from both tubes) reconstructed with FBP (Group 1); and (b) low-dose images (generated from tube A; 60% dose reduction) reconstructed with SAFIRE (Group 2). The CT parameters analyzed on both groups of images included: (a) subjective and objective image noise on lung and mediastinal images; (b) the presence and conspicuity of elementary lesions of lung infiltration.

In Group 2 images, there was: (a) a significant reduction in the objective image noise measured at the level of the trachea on mediastinal (16.04 ±5.66 vs 17.66 ±5.84) (p=0.0284) and lung images (29.77±6.79 vs 37.96 ±9.03) (p<0.0001); (b) a similar visual perception of noise on mediastinal (p=1) and lung images (p=1), mainly rated as minimal; and (d) a similar overall image quality, rated as excellent in 66% (33/50) of examinations, without loss of diagnostic information as assessed by the comparative analysis of individual CT features of lung infiltration (98.4 %; 95% CI=[96.9%-99.9%]).

Despite a 60% dose reduction, low-dose images reconstructed with SAFIRE had a similar subjective and a better objective image quality compared to full-dose FBP images.

Iterative reconstruction is a useful tool to implement marked dose reduction in clinical practice without impairing the diagnostic value of chest CT examinations.

Pontana, F, Moureau, D, Schmidt, B, Yasunaga, K, Remy, J, Remy-Jardin, M, Can Iterative Reconstruction Restore Image Quality at 60% Dose Reduction: Clinical Experience in 50 Patients with Simultaneous Availability of Low-Dose and Standard-Dose Images from Dual-Source Datasets.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043719.html