CT pulmonary angiogram with 60% dose reduction: Influence of iterative reconstructions on image quality

Goals: To compare the quality of low-dose CT images with sinogram affirmed iterative reconstruction (SAFIRE), and full-dose CT with filtered back projection reconstructions (FBP).

Materials and methods: Fifty pulmonary CT performed by a dual-source technique (120kVp; 110mAs) with (a) the same energy in both tubes, and (b) the distribution of reference mAs with 40% in tube A (44mAs) and 60% in tube B (66mAs). Each acquisition allowed reconstruction of: (a) full-dose images (with both tubes) with FBP reconstructions (group 1); and (b) low-dose images (from tube A) reconstructed with SAFIRE (group 2).

Results: Group 2 images presented: (a) a significant objective reduction in noise measured in the trachea on mediastinal (16.04±5.66 vs 17.66±5.84) (P=0.0284) and pulmonary (29.77±6.79 vs 37.96±9.03) (P<0.0001) images; (b) a similar subjective perception of noise and overall image quality (P=1), which was considered to be excellent in 66% (33/50) of the cases, with no influence on the detection of elementary pulmonary lesions of infiltration (98.4%; 95% CI=[96.9%-99.9%]).

Conclusion: Despite a 60% reduction in radiation dose, the image quality with iterative reconstruction is objectively better and subjectively similar to full-dose FBP images.