| Objective:To characterize the optimal pre-adaptive and post-adaptive level statistical iterative reconstruction V（ASiR-V）for improving image quality and reducing the radiation dose in coronary computed tomography angiography（CCTA）.Methods:The study was divided into two parts.In part I:150 patients for CCTA were prospectively enrolled and randomly divided into five groups（A,B,C,D,and E）,with progressive scanning from 40%to 80%pre-ASiR-V with 10%intervals and reconstructing with 70%post-ASiR-V.The signal-to-noise ratio（SNR）and contrast-to-noise ratio（CNR）were calculated.Subjective image quality was assessed using a five-point scale.The CT dose index volume(CTDIvol)and dose-length product（DLP）of each patient were recorded and the effective radiation dose（ED）was calculated after statistical analysis by optimizing for the best pre-ASiR-V value with the lowest radiation dose while maintaining overall image quality.In part II:The images with the best pre-ASiR-V value in Part I（group D）were reconstructed into 6subgroups（D0,D1,D2,D3,D4,D5）with 40-90%（interval 10%）post-ASiR-V.The SNR,CNR and subjective scores of each subgroup were recorded after statistical analysis by optimizing for the best post-ASiR-V value while maintaining overall image quality.Results:There was no significant difference in the SNRs,CNRs,and image quality scores among A,B,C,and D groups（P=.313）.The SNR,CNR,and image quality scores of the E group were lower than those of the A,B,C,and D groups（P<0.001）.The mean ED values in the B,C,and D groups were reduced by 7.01%,13.37%,and18.87%,respectively,when compared with that of the A group.The SNR and CNR of the D4–D5 subgroups were higher than the D0-D3 subgroups,and the image quality scores of the D4 subgroups were higher than the other subgroups（P<0.001）.Conclusion:The wide-detector combined with 70%pre-ASiR-V and 80%post-ASiR-V significantly reduced the radiation dose of CCTA while maintaining overall image quality compared with the manufacture’s recommendation. |
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