To evaluate image quality and diagnostic confidence and accuracy of a raw-data-based iterative reconstruction technique (SAFIRE) in reduced-dose CCTA images in comparison with standard-dose filtered back projection (FBP) images.

32 consecutive patients (23 males; 9 females), referred for a CCTA were prospectively included using a dual source CT system in a high pitch (n=18) or a sequential prospective gating scanning mode (n=14) according to the heart rate (mean DLP value = 197.7 mGy.cm). From each acquisition 4 series of images were reconstructed: (a) standard-dose images, reconstructed with FBP considered as the reference standard (Group 1) and (b) 3 series of reduced-dose images, obtained with a prototype software which virtually increased the level of noise...

In Group 2, a significant increase in the mean level of objective noise compared to Group 1 (35.70 ±5.54 vs 29.97 ±4.39; p<0.0001) and a CNR impairment (15.72 ±3.58 vs 18.63 ±4.00; p<0.0001) were associated to a lower diagnostic confidence (p= 0.03), mainly rated as moderate. In Group 3 and 4, despite the 30% dose reduction, SAFIRE restored or improved the objective image quality respectively: (a) mean noise= 30.05 ±3.95; p=0.8 & 21.89 ±3.62; p<0.0001, and (b) CNR= 18.73 ±4.05; p=0.7 & 25.84 ±5.73; p<0.0001....

Raw-data-based iterative reconstruction allowed significant image noise reduction but may be associated with a blurred aspect of the coronary borders, which can decrease diagnostic confidence. When reporting reduced-dose CCTA with iterative reconstruction, blurred-border and false smooth plaque artifacts must be considered in diagnostic assessment and subsequent patient management.